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British Airways

British Airways plc (BA) is the flag carrier airline of the United Kingdom. It is headquartered in London, England, near its main hub at Heathrow Airport.

The airline is the second largest UK-based carrier, based on fleet size and passengers carried, behind easyJet. In January 2011 BA merged with Iberia, creating the International Airlines Group (IAG), a holding company registered in Madrid, Spain. IAG is the world's third-largest airline group in terms of annual revenue and the second-largest in Europe. It is listed on the London Stock Exchange and in the FTSE 100 Index. British Airways is the first passenger airline to have generated more than US$1 billion on a single air route in a year (from 1 April 2017, to 31 March 2018, on the New York-JFK – London-Heathrow route).

BA was created in 1974 after a British Airways Board was established by the British government to manage the two nationalised airline corporations, British Overseas Airways Corporation and British European Airways, and two regional airlines, Cambrian Airways and Northeast Airlines. On 31 March 1974, all four companies were merged to form British Airways. However, it marked 2019 as its centenary based on predecessor companies. After almost 13 years as a state company, BA was privatised in February 1987 as part of a wider privatisation plan by the Conservative government. The carrier expanded with the acquisition of British Caledonian in 1987, Dan-Air in 1992, and British Midland International in 2012.

It is a founding member of the Oneworld airline alliance, along with American Airlines, the now-defunct Canadian Airlines, Cathay Pacific, and Qantas. The alliance has since grown to become the third-largest, after SkyTeam and Star Alliance.

History

Proposals to establish a joint British airline, combining the assets of the British Overseas Airways Corporation (BOAC) and British European Airways (BEA), were first raised in 1953 as a result of difficulties in attempts by BOAC and BEA to negotiate air rights through the British colony of Cyprus. Increasingly BOAC was protesting that BEA was using its subsidiary Cyprus Airways to circumvent an agreement that BEA would not fly routes further east than Cyprus, particularly to the increasingly important oil regions in the Middle East. The chairman of BOAC, Miles Thomas, was in favour of a merger as a potential solution to this disagreement and had backing for the idea from the Chancellor of the Exchequer at the time, Rab Butler. However, opposition from the Treasury blocked the proposal.

Consequently, it was only following the recommendations of the 1969 Edwards Report that a new British Airways Board, managing both BEA and BOAC, and the two regional British airlines Cambrian Airways based at Cardiff, and Northeast Airlines based at Newcastle upon Tyne, was constituted on 1 April 1972. Although each airline's branding was maintained initially, two years later the British Airways Board unified its branding, effectively establishing British Airways as an airline on 31 March 1974.

Following two years of fierce competition with British Caledonian, the second-largest airline in the United Kingdom at the time, the Government changed its aviation policy in 1976 so that the two carriers would no longer compete on long-haul routes.

British Airways and Air France operated the supersonic Concorde airliner, and the world's first supersonic passenger service flew on 21 January 1976 from Heathrow Airport to Bahrain International Airport. Services to the U.S. began on 24 May 1976 with a flight to Washington Dulles airport, and flights to New York JFK airport followed on 22 September 1977. Service to Singapore was established in co-operation with Singapore Airlines as a continuation of the flight to Bahrain. Following the Air France Concorde crash in Paris and a slump in air travel following the 11 September attacks in New York in 2001, it was decided to cease Concorde operations in 2003 after 27 years of service. The final commercial Concorde flight was BA002 from New York-JFK to London-Heathrow on 24 October 2003.

In 1981 the airline was instructed to prepare for privatisation by the Conservative Thatcher government. Sir John King, later Lord King, was appointed chairman, charged with bringing the airline back into profitability. While many other large airlines struggled, King was credited with transforming British Airways into one of the most profitable air carriers in the world. The flag carrier was privatised and was floated on the London Stock Exchange in February 1987. British Airways effected the takeover of the UK's "second" airline, British Caledonian, in July of that same year.

The formation of Richard Branson's Virgin Atlantic in 1984 created a competitor for BA. The intense rivalry between British Airways and Virgin Atlantic culminated in the former being sued for libel in 1993, arising from claims and counterclaims over a "dirty tricks" campaign against Virgin. This campaign included allegations of poaching Virgin Atlantic customers, tampering with private files belonging to Virgin, and undermining Virgin's financial reputation in the city. As a result of the case BA management apologised "unreservedly", and the company agreed to pay £110,000 in damages to Virgin, £500,000 to Branson personally and £3 million legal costs. Lord King stepped down as chairman in 1993 and was replaced by his deputy, Colin Marshall, while Bob Ayling took over as CEO. Virgin filed a separate action in the U.S. that same year regarding BA's domination of the trans-Atlantic routes, but it was thrown out in 1999.

In 1992 British Airways expanded through the acquisition of the financially troubled Dan-Air, giving BA a much larger presence at Gatwick Airport. British Asia Airways, a subsidiary based in Taiwan, was formed in March 1993 to operate between London and Taipei. That same month BA purchased a 25% stake in the Australian airline Qantas and, with the acquisition of Brymon Airways in May, formed British Airways Citiexpress (later BA Connect). In September 1998, British Airways, along with American Airlines, Cathay Pacific, Qantas, and Canadian Airlines, formed the Oneworld airline alliance. Oneworld began operations on 1 February 1999, and is the third-largest airline alliance in the world, behind SkyTeam and Star Alliance.

Bob Ayling's leadership led to a cost savings of £750m and the establishment of a budget airline, Go, in 1998. The next year, however, British Airways reported an 84% drop in profits in its first quarter alone, its worst in seven years. In March 2000, Ayling was removed from his position and British Airways announced Rod Eddington as his successor. That year, British Airways and KLM conducted talks on a potential merger, reaching a decision in July to file an official merger plan with the European Commission. The plan fell through in September 2000. British Asia Airways ceased operations in 2001 after BA suspended flights to Taipei. Go was sold to its management and the private equity firm 3i in June 2001. Eddington would make further workforce cuts due to reduced demand following 11 September attacks in 2001, and BA sold its stake in Qantas in September 2004. In 2005 Willie Walsh, managing director of Aer Lingus and a former pilot, became the chief executive officer of British Airways. BA unveiled its new subsidiary OpenSkies in January 2008, taking advantage of the liberalisation of transatlantic traffic rights between Europe and the United States. OpenSkies flies non-stop from Paris to New York's JFK and Newark airports.

In July 2008, British Airways announced a merger plan with Iberia, another flag carrier airline in the Oneworld alliance, wherein each airline would retain its original brand. The agreement was confirmed in April 2010, and in July the European Commission and U.S. Department of Transportation permitted the merger and began to co-ordinate transatlantic routes with American Airlines. On 6 October 2010 the alliance between British Airways, American Airlines and Iberia formally began operations. The alliance generates an estimated £230 million in annual cost-saving for BA, in addition to the £330 million which would be saved by the merger with Iberia. This merger was finalised on 21 January 2011, resulting in the establishment of International Airlines Group S.A. (IAG), the world's third-largest airline in terms of annual revenue and the second-largest airline group in Europe. Prior to merging, British Airways owned a 13.5% stake in Iberia, and thus received ownership of 55% of the combined International Airlines Group; Iberia's other shareholders received the remaining 45%. As a part of the merger, British Airways ceased trading independently on the London Stock Exchange after 23 years as a constituent of the FTSE 100 Index.

In September 2010 Willie Walsh, now CEO of IAG, announced that the group was considering acquiring other airlines and had drawn up a shortlist of twelve possible acquisitions. In November 2011 IAG announced an agreement in principle to purchase British Midland International from Lufthansa. A contract to purchase the airline was agreed the next month, and the sale was completed for £172.5 million on 30 March 2012. The airline established a new subsidiary based at London City Airport operating Airbus A318s.

British Airways was the official airline partner of the London 2012 Olympic Games. On 18 May 2012 it flew the Olympic flame from Athens International Airport to RNAS Culdrose while carrying various dignitaries, including Lord Sebastian Coe, Princess Anne, the Olympics minister Hugh Robertson and the London Mayor Boris Johnson, along with the footballer David Beckham.

On 27 May 2017, British Airways suffered a computer power failure. All flights were cancelled and thousands of passengers were affected. By the following day, the company had not succeeded in reestablishing the normal function of its computer systems. When asked by reporters for more information on the ongoing problems, British Airways stated "The root cause was a power supply issue which our affected our IT systems - we continue to investigate this" and declined to comment further. Willie Walsh later attributed the crash to an electrical engineer disconnecting the UPS and said there would be an independent investigation.

Amidst the decline in the value of Iranian currency due to the reintroduction of U.S. sanctions on Iran, BA announced that the Iranian route is "not commercially viable". As a result, BA decided to stop its services in Iran, effective 22 September 2018.

In 2018, British Airways partnered with British tailor and designer Ozwald Boateng to redesign the company's historic uniforms, in honour of its approaching centenary, creating a new look for BA, while adhering to its traditional style. The new collection "A British Original" was launched in 2023. This design initiative also included English bone china manufactured by William Edwards and cutlery by Studio William for the company's first class service.

In 2019, as part of the celebrations of a centenary of airline operations in the United Kingdom, British Airways announced that four aircraft would receive retro liveries. The first of these is a Boeing 747-400 (G-BYGC), which was repainted into the former BOAC livery, which it retained until its retirement. Two more Boeing 747-400s were repainted with former British Airways liveries. One wore the "Landor" livery until its retirement in 2020 (G-BNLY), the other (G-CIVB), wore the original "Union Jack" livery until its retirement in 2020 also. An Airbus A319 was repainted into British European Airways livery, which is still flying as G-EUPJ.

On 28 April 2020, the company set out plans to make up to 12,000 staff redundant because of the global collapse of air traffic due to the COVID-19 pandemic and that it may not reopen its operations at Gatwick airport. They reopened at Gatwick in March 2022.

In July 2020, British Airways announced the immediate retirement of its entire 747-400 fleet, having originally intended to phase out the remaining 747s in 2024. The airline stated that its decision to bring forward the date was in part due to the downturn in air travel following the COVID-19 pandemic and to focus on incorporating more modern and fuel-efficient aircraft such as the Airbus A350 and Boeing 787. At the same time, British Airways also announced its intention to eliminate carbon emissions by 2050. On 28 July 2020, the company's cabin crew union issued an "industrial action" warning in order to prevent the 12,000 job cuts and pay cuts.

On 12 October 2020, it was announced that Sean Doyle, CEO of Aer Lingus (also part of the IAG airline group) would succeed Álex Cruz as CEO.

Operations
British Airways is the largest airline based in the United Kingdom in terms of fleet size, international flights, and international destinations and was, until 2008, the largest airline by passenger numbers. The airline carried 34.6 million passengers in 2008, but, rival carrier easyJet transported 44.5 million passengers that year, passing British Airways for the first time. British Airways holds a United Kingdom Civil Aviation Authority Type A Operating Licence, it is permitted to carry passengers, cargo, and mail on aircraft with 20 or more seats.

The airlines' head office, Waterside, stands in Harmondsworth, a village that is near Heathrow Airport. Waterside was completed in June 1998 to replace British Airways' previous head office, Speedbird House, located in Technical Block C on the grounds of Heathrow.

British Airways' main base is at Heathrow Airport, but it also has a major presence at Gatwick Airport. It also has a base at London City Airport, where its subsidiary BA Cityflyer is the largest operator. BA had previously operated a significant hub at Manchester Airport. Manchester to New York (JFK) services were withdrawn; later all international services outside London ceased when the subsidiary BA Connect was sold. Passengers wishing to travel internationally with BA either to or from regional UK destinations must now transfer in London. Heathrow Airport is dominated by British Airways, which owns 50% of the slots available at the airport as of 2019, growing from 40% in 2004. The majority of BA services operate from Terminal 5, with the exception of some flights at Terminal 3 owing to insufficient capacity at Terminal 5. At London City Airport, the company owns 52% of the slots as of 2019.

In August 2014, Willie Walsh advised the airline would continue to use flight paths over Iraq despite the hostilities there. A few days earlier Qantas announced it would avoid Iraqi airspace, while other airlines did likewise. The issue arose following the downing of Malaysia Airlines Flight 17 over Ukraine, and a temporary suspension of flights to and from Ben Gurion Airport during the 2014 Israel–Gaza conflict.

Subsidiaries
Over its history, BA has had many subsidiaries. In addition to the below, British Airways also owned Airways Aero Association, the operator of the British Airways flying club based at Wycombe Air Park in High Wycombe, until it was sold to Surinder Arora in 2007.

Shareholdings
British Airways obtained a 15% stake in UK regional airline Flybe from the sale of BA Connect in March 2007. It sold the stake in 2014.

BA also owned a 10% stake in InterCapital and Regional Rail (ICRR), the company that managed the operations of Eurostar (UK) Ltd from 1998 to 2010, when the management of Eurostar was restructured.

Business trends
The key trends for the British Airways PLC Group are shown below.

On the merger with Iberia, the accounting reference date was changed from 31 March to 31 December; figures below are therefore for the years to 31 March up to 2010, for the nine months to 31 December 2010, and for the years to 31 December thereafter:

In 2020, due to the crisis caused by the COVID-19 pandemic, British Airways had to reduce its 42,000-strong workforce by 12,000 jobs. According to the estimate by IAG, a parent company, it will take the air travel industry several years to return to previous performance and profitability levels.

However, 2022 saw a dramatic increase in travel, and the company now faced a worker shortage, forcing it to cancel more than 1,500 flights. During February 2023, The international airlines group, the owners of British Airways announced that the group has returned to making an annual profit of €1.3 billion for the first time since the pandemic, following a €2.8 billion loss in 2021. The company warned that due to the surge in demand for flying this could lead to more disruption.

Industrial relations
Staff working for British Airways are represented by a number of trade unions, pilots are represented by British Air Line Pilots' Association, cabin crew by British Airlines Stewards and Stewardesses Association (a branch of Unite the Union), while other branches of Unite the Union and the GMB Union represent other employees. Bob Ayling's management faced strike action by cabin crew over a £1 billion cost-cutting drive to return BA to profitability in 1997; this was the last time BA cabin crew would strike until 2009, although staff morale has reportedly been unstable since that incident. In an effort to increase interaction between management, employees, and the unions, various conferences and workshops have taken place, often with thousands in attendance.

In 2005, wildcat action was taken by union members over a decision by Gate Gourmet not to renew the contracts of 670 workers and replace them with agency staff; it is estimated that the strike cost British Airways £30 million and caused disruption to 100,000 passengers. In October 2006, BA became involved in a civil rights dispute when a Christian employee was forbidden to wear a necklace bearing the cross, a religious symbol. BA's practice of forbidding such symbols has been publicly questioned by British politicians such as the former Home Secretary John Reid and the former Foreign Secretary Jack Straw.

Relations have been turbulent between BA and Unite. In 2007, cabin crew threatened strike action over salary changes to be imposed by BA management. The strike was called off at the last minute, British Airways losing £80 million. In December 2009, a ballot for strike action over Christmas received a high level of support, action was blocked by a court injunction that deemed the ballot illegal. Negotiations failed to stop strike action in March, BA withdrew perks for strike participants. Allegations were made by The Guardian newspaper that BA had consulted outside firms methods to undermine the unions: the story was later withdrawn. A strike was announced for May 2010, British Airways again sought an injunction. Members of the Socialist Workers Party disrupted negotiations between BA management and Unite to prevent industrial action. Further disruption struck when Derek Simpson, a Unite co-leader, was discovered to have leaked details of confidential negotiations online via Twitter. Industrial action re-emerged in 2017, this time by BA's Mixed Fleet flight attendants, whom were employed on much less favorable pay and terms and conditions compared to previous cabin staff who joined prior to 2010. A ballot for industrial action was distributed to Mixed Fleet crew in November 2016 and resulted in an overwhelming yes majority for industrial action. Unite described Mixed Fleet crew as on "poverty pay", with many Mixed Fleet flight attendants sleeping in their cars in between shifts because they cannot afford the fuel to drive home, or operating while sick as they cannot afford to call in sick and lose their pay for the shift. Unite also blasted BA of removing staff travel concessions, bonus payments and other benefits to all cabin crew who undertook industrial action, as well as strike-breaking tactics such as wet-leasing aircraft from other airlines and offering financial incentives for cabin crew not to strike. The first dates of strikes during Christmas 2016 were cancelled due to pay negotiations. Industrial action by Mixed Fleet commenced in January 2017 after rejecting a pay offer. Strike action continued throughout 2017 in numerous discontinuous periods, resulting in one of the longest running disputes in aviation history. On 31 October 2017, after 85 days of discontinuous industrial action, Mixed Fleet accepted a new pay deal from BA which ended the dispute.

Senior Leadership

 * Chairman: Sean Doyle (since April 2021)
 * Chief Executive: Sean Doyle (since October 2020)

List of Former Chairmen

 * 1) Sir David Nicolson (1972–1975)
 * 2) The Lord McFadzean (1976–1979)
 * 3) Sir Ross Stainton (1979–1980)
 * 4) The Lord King (1981–1993)
 * 5) The Lord Marshall (1993–2004)
 * 6) Sir Martin Broughton (2004–2013)
 * 7) Keith Williams (2013–2016)
 * 8) Álex Cruz (2016–2021)

List of Former Chief Executives
The position was formed in 1977.

 * 1) Sir Ross Stainton (1977–1979)
 * 2) Sir Roy Watts (1979–1983)
 * 3) The Lord Marshall (1983–1995)
 * 4) Bob Ayling (1996–2000)
 * 5) Sir Rod Eddington (2000–2005)
 * 6) Willie Walsh (2005–2010)
 * 7) Keith Williams (2011–2016)
 * 8) Álex Cruz (2016–2020)

Destinations

British Airways serves over 170 destinations in 70 countries, including eight domestic and 27 in the United States.

Alliances
British Airways co-founded the airline alliance Oneworld in 1999 with airlines American Airlines, Cathay Pacific and Qantas. British Airways is still currently a member of Oneworld.

Codeshare agreements
British Airways has codeshares with the following airlines:

 * Aer Lingus
 * airBaltic
 * Alaska Airlines
 * American Airlines
 * Bangkok Airways
 * Cathay Pacific
 * China Eastern Airlines
 * China Southern Airlines
 * Finnair
 * Iberia
 * Japan Airlines
 * Kenya Airways
 * LATAM Brasil
 * LATAM Chile
 * Loganair
 * Malaysia Airlines
 * Qantas
 * Qatar Airways
 * Royal Jordanian
 * S7 Airlines
 * TAAG Angola Airlines
 * Vueling

Fleet
, the British Airways operates a fleet of 253 aircraft with 47 orders. BA operates a mix of Airbus narrow and wide-body aircraft, and Boeing wide-body aircraft, specifically the 777 and 787. In October 2020, British Airways retired its fleet of 747-400 aircraft. It was one of the largest operators of the 747, having previously operated the -100, -200, and -400 aircraft from 1974 (1969 with BOAC).

British Airways Engineering
The airline has its own engineering branch to maintain its aircraft fleet, this includes line maintenance at over 70 airports around the world. As well as hangar facilities at Heathrow and Gatwick airport it has two major maintenance centres at Glasgow and Cardiff Airports.

Branding

The musical theme predominantly used on British Airways advertising has been "The Flower Duet" by Léo Delibes. This was first used in a 1984 advertisement directed by Tony Scott, in an arrangement by Howard Blake. It was reworked by Malcolm McLaren and Yanni for 1989's iconic "Face" advertisement, and subsequently appeared in many different arrangements between 1990 and 2010. The slogan 'the world's favourite airline', first used in 1983, was dropped in 2001 after Lufthansa overtook BA in terms of passenger numbers. Other advertising slogans have included "The World's Best Airline", "We'll Take More Care of You", "Fly the Flag", and "To Fly, To Serve".

BA had an account for 23 years with Saatchi & Saatchi, an agency that created many of their most famous advertisements, including "The World's Biggest Offer" and the influential "Face" campaign. Saatchi & Saatchi later imitated this advert for Silverjet, a rival of BA, after BA discontinued their business activities. Since 2007, BA used Bartle Bogle Hegarty as its advertising agency.

In October 2022, BA launched a brand new ad campaign, titled "A British Original" produced by London-based Uncommon Creative Studio. This was to be another record-breaking campaign for its use of 500 unique executions along with a series of 32 short films, coinciding with the launch of Ozwald Boateng's new collection of uniform.

British Airways purchased the internet domain ba.com in 2002 from previous owner Bell Atlantic, 'BA' being the company's initialism and its IATA Airline code.

British Airways is the official airline of the Wimbledon Championship tennis tournament, and was the official airline and tier one partner of the 2012 Summer Olympics and Paralympics. BA was also the official airline of England's bid to host the 2018 Football World Cup.

High Life, founded in 1973, is the official in-flight magazine of the airline.

Safety video
The airline used a cartoon safety video from circa 2005 until 2017. Beginning on 1 September 2017 the airline introduced the new Comic Relief live action safety video hosted by Chabuddy G, with appearances by British celebrities Gillian Anderson, Rowan Atkinson, Jim Broadbent, Rob Brydon, Warwick Davis, Chiwetel Ejiofor, Ian McKellen, Thandie Newton, and Gordon Ramsay. A "sequel" video, also hosted by Chabuddy G, was released in 2018, with Michael Caine, Olivia Colman, Jourdan Dunn, Naomie Harris, Joanna Lumley, and David Walliams. The two videos are part of Comic Relief's charity programme. On 17 April 2023, the airline launched a new safety video as a part of “A British Original” campaign, with Emma Raducanu, Robert Peston, Little Simz, and Steven Bartlett.

Liveries, logos, and tail fins
The aeroplanes that British Airways inherited from the four-way merger between BOAC, BEA, Cambrian, and Northeast were temporarily given the text logo "British airways" but retained the original airline's livery. With its formation in 1974, British Airways' aeroplanes were given a new white, blue, and red colour scheme with a cropped Union Jack painted on their tail fins, designed by Negus & Negus. In 1984, a new livery designed by Landor Associates updated the airline's look as it prepared for privatization. For celebrating centenary, BA announced four retro liveries: three on Boeing 747-400 aircraft (one in each of BOAC, Negus & Negus, and Landor Associates liveries), and one A319 in BEA livery.

In 1997, there was a controversial change to a new Project Utopia livery; all aircraft used the corporate colours consistently on the fuselage, but tailfins bore one of multiple designs. Several people spoke out against the change, including the former prime minister Margaret Thatcher, who famously covered the tail of a model 747 at an event with a handkerchief, to show her displeasure. BA's traditional rival, Virgin Atlantic, took advantage of the negative press coverage by applying the Union flag to the winglets of their aircraft along with the slogan "Britain's national flagcarrier".

In 1999, the CEO of British Airways, Bob Ayling, announced that all BA planes would adopt the tailfin design Chatham Dockyard Union Flag originally intended to be used only on the Concorde, based on the Union Flag. All BA aircraft have since borne the Chatham Dockyard Union flag variant of the Project Utopia livery, except for the four retro aircraft.

Arms
In 2011, British Airways made a brand relaunch project, in which BA introduced a stylised, metallic version of the arms by For People Design to be used along with its Speedmarque logo. This is used exclusively on aircraft, First Wing Lounge and advertisements.

Loyalty programmes
British Airways' tiered loyalty programme, called the Executive Club, includes access to special lounges and dedicated "fast" queues. Its programme consists of six tiers: Blue, Bronze, Silver, Gold, Gold guest list and Premier. BA invites its top corporate accounts to join the "Premier" incentive programme.

The programme incentivises its members to fly with BA by awarding them Avios and Tier Points. Avios is the spending currency, which can be redeemed. Tier Points are a score used to determine the member's tier, and cannot be redeemed. Tier Points are reset at the end of each membership year, and Avios are retained for three years.

British Airways operates airside lounges for passengers travelling in premium cabins, and these are available to certain tiers of Executive Club members. First class passengers, as well as Gold Executive Club members, are entitled to use First Class Lounges. Business class passengers (called Club World or Club Europe in BA terms) as well as Silver Executive Club members may use Business lounges. At airports in which BA does not operate a departure lounge, a third party lounge is often provided for premium or status passengers.

Members of the programme were also granted status within the Oneworld alliance, which permitted similar benefits when flying with Oneworld member airlines. The level of benefits were determined by the member's tier.

Economy class
Euro Traveller is British Airways' economy class cabin on all short-haul flights within Europe, including domestic flights within the UK. Heathrow and Gatwick-based flights are operated by Airbus A320 series aircraft. Standard seat pitch varies from 29" to 34" depending on aircraft type and location of the seat.

All flights from Heathrow and Gatwick have a buy on board system with a range of food designed by Tom Kerridge. Food can be pre-ordered through the British Airways mobile application. Alternatively, a limited selection can be purchased on-board using credit and debit card or by using Frequent Flyer Avios points. British Airways is rolling out Wi-Fi across its fleet of aircraft with 90% expected to be Wi-Fi enabled by 2020.

Business class
Club Europe is the short-haul business class available on all short-haul flights. This class allows for access to business lounges at most airports and complimentary onboard catering. The middle seat of the standard Airbus configured cabin is left free. Instead, a cocktail table folds up from under the middle seat on refurbished aircraft. Pillows and blankets are available on longer flights.

In-flight

First class
First is offered on all Airbus A380s, Boeing 777-300ERs, Boeing 787-9/10s and on some Boeing 777-200ERs. There are between eight and fourteen private suites depending on the aircraft type. Each First suite comes with a 6 ft bed, a 15 in wide entertainment screen, in-seat power and complimentary Wi-Fi access on select aircraft.

The exclusive Concorde Room lounge at Heathrow Terminal 5 offers pre-flight dining with waiter service and more intimate space. Dedicated British Airways 'Galleries First' lounges are available at some airports, and Business lounges are used where these are not available. Some feature a 'First Dining' section where passengers holding a first class ticket can access a pre-flight dining service.

Club World
Club World is the long-haul business class cabin. It is offered on all long-haul aircraft. The cabin features fully convertible flat bed seats. In March 2019, BA unveiled its new business-class seats - named Club Suite - on the new A350 aircraft, which feature a suite with a door. Since the unveiling, Club Suite has been installed on the Boeing 787-10 and is currently being installed on BA's Boeing 777s. The remaining aircraft are due to have their seats re-fitted over the coming years and they currently feature an older seat type introduced in 2006.

World Traveller Plus
World Traveller Plus is the premium economy class cabin provided on all BA long haul aircraft. This cabin offers wider seats, extended leg-room, additional seat comforts such as larger IFE screen, a foot rest and power sockets. A complimentary 'World Traveller' bar is offered along with an upgraded main meal.

World Traveller
World Traveller is the mid-haul and long-haul economy class cabin. It offers seat-back entertainment, complimentary food and drink, pillows, and blankets. While the in-flight entertainment screens are available on all long-haul aircraft, international power outlets are available on the aircraft based at Heathrow. Wifi is also available on selected aircraft at an extra fee.

Incidents and accidents
British Airways is known to have a strong reputation for safety and has been consistently ranked within the top 20 safest airlines globally according to Business Insider and AirlineRatings.com.

Since BA's inception in 1974, it has been involved in three hull-loss incidents (British Airways Flight 149 was destroyed on the ground at Kuwait International Airport as a result of military action during the First Gulf War with no one on board) and two hijacking attempts. To date, the only fatal accident experienced by a BA aircraft occurred in 1976 with British Airways Flight 476 which was involved in a midair collision later attributed to an error made by air traffic control.

 * On 22 November 1974, British Airways Flight 870 was hijacked shortly after take-off from Dubai International Airport for London-Heathrow. The Vickers VC10 landed at Tripoli for refuelling before flying on to Tunis. The captain, Jim Futcher, returned to the aircraft to fly it knowing the hijackers were on board. A hostage, 43-year-old German banker Werner Gustav Kehl, was shot in the back. The hijackers eventually surrendered after 84 hours. Futcher was awarded the Queen's Gallantry Medal, the Guild of Air Pilots and Air Navigators Founders Medal, the British Air Line Pilots Association Gold Medal and a Certificate of Commendation from British Airways for his actions during the hijacking.
 * On 10 September 1976, a Trident 3B on British Airways Flight 476 departed from London-Heathrow to Istanbul. It collided in mid-air with an Inex Adria DC9-31 near Zagreb. All 54 passengers and 9 crew members on the BA aircraft died. This is the only fatal accident to a British Airways aircraft since the company's formation in 1974.
 * On 24 June 1982, British Airways Flight 9, a Boeing 747-200 registration G-BDXH, flew through a cloud of volcanic ash and dust from the eruption of Mount Galunggung. The ash and dust caused extensive damage to the aircraft, including the failure of all four engines. The crew managed to glide the plane out of the dust cloud and restart all four of its engines, although one later had to be shut down again. The volcanic ash caused the cockpit window to be scratched to such an extent that it was difficult for the pilots to see out of the plane. However, the aircraft made a successful emergency landing at Halim Perdanakusuma International Airport just outside Jakarta. There were no fatalities or injuries.
 * On 10 June 1990, British Airways Flight 5390, a BAC One-Eleven flight between Birmingham and Málaga, suffered a windscreen blowout due to the fitting of incorrect bolts the previous day. The captain sustained major injuries after being partially blown out of the aircraft, but the co-pilot landed the plane safely at Southampton Airport.
 * On 2 August 1990, British Airways Flight 149 landed at Kuwait International Airport four hours after the Iraqi invasion of Kuwait. The aircraft, a Boeing 747-100 G-AWND, was destroyed, and all passengers and crew were captured. Two of the landing gears were salvaged, and are on display in Waterside, BA Headquarters in London.
 * On 29 December 2000, British Airways Flight 2069 was en route from London to Nairobi when a mentally ill passenger entered the cockpit and grabbed the controls. As the pilots struggled to remove the intruder, the Boeing 747-400 stalled twice and banked to 94 degrees. Several people on board were injured by the violent manoeuvres, which briefly caused the aircraft to descend at 30,000 ft per minute. The man was finally restrained with the help of several passengers, and the co-pilot regained control of the aircraft. The flight landed safely in Nairobi.

 * On 17 January 2008, British Airways Flight 38, a Boeing 777-200ER G-YMMM, from Beijing to London crash-landed approximately 1000 ft short of Heathrow Airport's runway 27L, and slid onto the runway's displaced threshold. The aircraft sustained damage to its landing gear, wing roots, and engines, resulting in the first hull loss of a Boeing 777. There were no fatalities, but there was one serious injury and 12 minor injuries. The accident was caused by icing in the fuel system, resulting in a loss of power.
 * On 24 May 2013, British Airways Flight 762, using an Airbus A319-131 and registered as G-EUOE, returned to Heathrow Airport after fan cowl doors detached from both engines shortly after takeoff. During the approach, a fire broke out in the right engine and persisted after the engine was shut down. The aircraft landed safely with no injuries to the 80 people on board. The accident report revealed that the cowlings had been left unlatched following overnight maintenance. The separation of the doors caused airframe damage and the right-hand engine fire resulted from a ruptured fuel pipe.
 * On 22 December 2013, British Airways Flight 34, a Boeing 747-436 G-BNLL, hit a building at O. R. Tambo International Airport in Johannesburg after missing a turning on a taxiway. The starboard wing was severely damaged but there were no injuries amongst the crew or 189 passengers, however, four members of ground staff were injured when the wing smashed into the building. The aircraft was officially withdrawn from service in February 2014.
 * On 8 September 2015, British Airways Flight 2276, a Boeing 777-236ER G-VIIO, aborted its takeoff at Las Vegas' McCarran International Airport due to an uncontained engine failure of its left (#1) General Electric GE90 engine, which led to a substantial fire. The aircraft was evacuated on the main runway. All 157 passengers and 13 crew escaped the aircraft, at least 14 people sustaining minor injuries.
 * Between 21 August 2018 and 5 September 2018, an attacker stole data for almost 500,000 British Airways customers, including credit card details for 250,000. The company was subsequently fined £20 million in October 2020, by the Information Commissioner's Office, the highest ever fine handed by the ICO at the time of issuing.
 * On 18 June 2021, a British Airways Boeing 787-8 G-ZBJB, had a nose landing gear collapse while on the tarmac at Heathrow Airport. A British Airways spokesperson confirmed that no passengers were on board the plane when the incident occurred.
 * On 6 July 2022, British Airways Flight 820, an Airbus A320-232 G-EUUV, caught fire as it was landing at Copenhagen Airport. Airport firefighters put out the fire. They had to use foam as well. People in the terminal buildings were able to record the footage. The plane was ferried back to London-Heathrow Airport on 9 July.

title: British Airways


text:
Bicycle

A bicycle, also called a pedal cycle, bike, push-bike or cycle, is a human-powered or motor-assisted, pedal-driven, single-track vehicle, with two wheels attached to a frame, one behind the other. A bicycle rider is called a cyclist, or bicyclist.

Bicycles were introduced in the 19th century in Europe. By the early 21st century there were more than 1 billion bicycles. There are many more bicycles than cars. Bicycles are the principal means of transport in many regions. They also provide a popular form of recreation, and have been adapted for use as children's toys. Bicycles are used for fitness, military and police applications, courier services, bicycle racing, and artistic cycling.

The basic shape and configuration of a typical upright or "safety" bicycle, has changed little since the first chain-driven model was developed around 1885. However, many details have been improved, especially since the advent of modern materials and computer-aided design. These have allowed for a proliferation of specialized designs for many types of cycling. In the 21st century, electric bicycles have become popular.

The bicycle's invention has had an enormous effect on society, both in terms of culture and of advancing modern industrial methods. Several components that played a key role in the development of the automobile were initially invented for use in the bicycle, including ball bearings, pneumatic tires, chain-driven sprockets, and tension-spoked wheels.

Etymology
The word bicycle first appeared in English print in The Daily News in 1868, to describe "Bysicles and trysicles" on the "Champs Elysées and Bois de Boulogne". The word was first used in 1847 in a French publication to describe an unidentified two-wheeled vehicle, possibly a carriage. The design of the bicycle was an advance on the velocipede, although the words were used with some degree of overlap for a time.

Other words for bicycle include "bike", "pushbike", "pedal cycle", or "cycle". In Unicode, the code point for "bicycle" is 0x1F6B2. The entity  in HTML produces 🚲.

Although bike and cycle are used interchangeably to refer mostly to two types of two-wheelers, the terms still vary across the world. In India, for example, a cycle refers only to a two-wheeler using pedal power whereas the term bike is used to describe a two-wheeler using internal combustion engine or electric motors as a source of motive power instead of motorcycle/motorbike.

History
The "dandy horse", also called Draisienne or Laufmaschine ("running machine"), was the first human means of transport to use only two wheels in tandem and was invented by the German Baron Karl von Drais. It is regarded as the first bicycle and von Drais is seen as the "father of the bicycle",   but it did not have pedals. Von Drais introduced it to the public in Mannheim in 1817 and in Paris in 1818. Its rider sat astride a wooden frame supported by two in-line wheels and pushed the vehicle along with his or her feet while steering the front wheel.

The first mechanically propelled, two-wheeled vehicle may have been built by Kirkpatrick MacMillan, a Scottish blacksmith, in 1839, although the claim is often disputed. He is also associated with the first recorded instance of a cycling traffic offense, when a Glasgow newspaper in 1842 reported an accident in which an anonymous "gentleman from Dumfries-shire... bestride a velocipede... of ingenious design" knocked over a little girl in Glasgow and was fined five shillings.

In the early 1860s, Frenchmen Pierre Michaux and Pierre Lallement took bicycle design in a new direction by adding a mechanical crank drive with pedals on an enlarged front wheel (the velocipede). This was the first in mass production. Another French inventor named Douglas Grasso had a failed prototype of Pierre Lallement's bicycle several years earlier. Several inventions followed using rear-wheel drive, the best known being the rod-driven velocipede by Scotsman Thomas McCall in 1869. In that same year, bicycle wheels with wire spokes were patented by Eugène Meyer of Paris. The French vélocipède, made of iron and wood, developed into the "penny-farthing" (historically known as an "ordinary bicycle", a retronym, since there was then no other kind). It featured a tubular steel frame on which were mounted wire-spoked wheels with solid rubber tires. These bicycles were difficult to ride due to their high seat and poor weight distribution. In 1868 Rowley Turner, a sales agent of the Coventry Sewing Machine Company (which soon became the Coventry Machinists Company), brought a Michaux cycle to Coventry, England. His uncle, Josiah Turner, and business partner James Starley, used this as a basis for the 'Coventry Model' in what became Britain's first cycle factory.

The dwarf ordinary addressed some of these faults by reducing the front wheel diameter and setting the seat further back. This, in turn, required gearing—effected in a variety of ways—to efficiently use pedal power. Having to both pedal and steer via the front wheel remained a problem. Englishman J.K. Starley (nephew of James Starley), J.H. Lawson, and Shergold solved this problem by introducing the chain drive (originated by the unsuccessful "bicyclette" of Englishman Henry Lawson), connecting the frame-mounted cranks to the rear wheel. These models were known as safety bicycles, dwarf safeties, or upright bicycles for their lower seat height and better weight distribution, although without pneumatic tires the ride of the smaller-wheeled bicycle would be much rougher than that of the larger-wheeled variety. Starley's 1885 Rover, manufactured in Coventry is usually described as the first recognizably modern bicycle. Soon the seat tube was added which created the modern bike's double-triangle diamond frame.

Further innovations increased comfort and ushered in a second bicycle craze, the 1890s Golden Age of Bicycles. In 1888, Scotsman John Boyd Dunlop introduced the first practical pneumatic tire, which soon became universal. Willie Hume demonstrated the supremacy of Dunlop's tyres in 1889, winning the tyre's first-ever races in Ireland and then England. Soon after, the rear freewheel was developed, enabling the rider to coast. This refinement led to the 1890s invention of coaster brakes. Dérailleur gears and hand-operated Bowden cable-pull brakes were also developed during these years, but were only slowly adopted by casual riders.

The Svea Velocipede with vertical pedal arrangement and locking hubs was introduced in 1892 by the Swedish engineers Fredrik Ljungström and Birger Ljungström. It attracted attention at the World Fair and was produced in a few thousand units.

In the 1870s many cycling clubs flourished. They were popular in a time when there were no cars on the market and the principal mode of transportation was horse-drawn vehicles, such the horse and buggy or the horsecar. Among the earliest clubs was The Bicycle Touring Club, which has operated since 1878. By the turn of the century, cycling clubs flourished on both sides of the Atlantic, and touring and racing became widely popular. The Raleigh Bicycle Company was founded in Nottingham, England in 1888. It became the biggest bicycle manufacturing company in the world, making over two million bikes per year.

Bicycles and horse buggies were the two mainstays of private transportation just prior to the automobile, and the grading of smooth roads in the late 19th century was stimulated by the widespread advertising, production, and use of these devices. More than 1 billion bicycles have been manufactured worldwide as of the early 21st century. Bicycles are the most common vehicle of any kind in the world, and the most numerous model of any kind of vehicle, whether human-powered or motor vehicle, is the Chinese Flying Pigeon, with numbers exceeding 500 million. The next most numerous vehicle, the Honda Super Cub motorcycle, has more than 100 million units made, while most produced car, the Toyota Corolla, has reached 44 million and counting.

Uses
Bicycles are used for transportation, bicycle commuting, and utility cycling. They are also used professionally by mail carriers, paramedics, police, messengers, and general delivery services. Military uses of bicycles include communications, reconnaissance, troop movement, supply of provisions, and patrol, such as in bicycle infantries.

They are also used for recreational purposes, including bicycle touring, mountain biking, physical fitness, and play. Bicycle sports include racing, BMX racing, track racing, criterium, roller racing, sportives and time trials. Major multi-stage professional events are the Giro d'Italia, the Tour de France, the Vuelta a España, the Tour de Pologne, and the Volta a Portugal. They are also used for entertainment and pleasure in other ways, such as in organised mass rides, artistic cycling and freestyle BMX.

Technical aspects

The bicycle has undergone continual adaptation and improvement since its inception. These innovations have continued with the advent of modern materials and computer-aided design, allowing for a proliferation of specialized bicycle types, improved bicycle safety, and riding comfort.

Types

Bicycles can be categorized in many different ways: by function, by number of riders, by general construction, by gearing or by means of propulsion. The more common types include utility bicycles, mountain bicycles, racing bicycles, touring bicycles, hybrid bicycles, cruiser bicycles, and BMX bikes. Less common are tandems, low riders, tall bikes, fixed gear, folding models, amphibious bicycles, cargo bikes, recumbents and electric bicycles.

Unicycles, tricycles and quadracycles are not strictly bicycles, as they have respectively one, three and four wheels, but are often referred to informally as "bikes" or "cycles".

Dynamics

A bicycle stays upright while moving forward by being steered so as to keep its center of mass over the wheels. This steering is usually provided by the rider, but under certain conditions may be provided by the bicycle itself.

The combined center of mass of a bicycle and its rider must lean into a turn to successfully navigate it. This lean is induced by a method known as countersteering, which can be performed by the rider turning the handlebars directly with the hands or indirectly by leaning the bicycle.

Short-wheelbase or tall bicycles, when braking, can generate enough stopping force at the front wheel to flip longitudinally. The act of purposefully using this force to lift the rear wheel and balance on the front without tipping over is a trick known as a stoppie, endo, or front wheelie.

Performance
The bicycle is extraordinarily efficient in both biological and mechanical terms. The bicycle is the most efficient human-powered means of transportation in terms of energy a person must expend to travel a given distance. From a mechanical viewpoint, up to 99% of the energy delivered by the rider into the pedals is transmitted to the wheels, although the use of gearing mechanisms may reduce this by 10–15%. In terms of the ratio of cargo weight a bicycle can carry to total weight, it is also an efficient means of cargo transportation.

A human traveling on a bicycle at low to medium speeds of around 16 – uses only the power required to walk. Air drag, which is proportional to the square of speed, requires dramatically higher power outputs as speeds increase. If the rider is sitting upright, the rider's body creates about 75% of the total drag of the bicycle/rider combination. Drag can be reduced by seating the rider in a more aerodynamically streamlined position. Drag can also be reduced by covering the bicycle with an aerodynamic fairing. The fastest recorded unpaced speed on a flat surface is 144.18 km/h.

In addition, the carbon dioxide generated in the production and transportation of the food required by the bicyclist, per mile traveled, is less than $1⁄10$ that generated by energy efficient motorcars.

Frame
The great majority of modern bicycles have a frame with upright seating that looks much like the first chain-driven bike. These upright bicycles almost always feature the diamond frame, a truss consisting of two triangles: the front triangle and the rear triangle. The front triangle consists of the head tube, top tube, down tube, and seat tube. The head tube contains the headset, the set of bearings that allows the fork to turn smoothly for steering and balance. The top tube connects the head tube to the seat tube at the top, and the down tube connects the head tube to the bottom bracket. The rear triangle consists of the seat tube and paired chain stays and seat stays. The chain stays run parallel to the chain, connecting the bottom bracket to the rear dropout, where the axle for the rear wheel is held. The seat stays connect the top of the seat tube (at or near the same point as the top tube) to the rear fork ends.

Historically, women's bicycle frames had a top tube that connected in the middle of the seat tube instead of the top, resulting in a lower standover height at the expense of compromised structural integrity, since this places a strong bending load in the seat tube, and bicycle frame members are typically weak in bending. This design, referred to as a step-through frame or as an open frame, allows the rider to mount and dismount in a dignified way while wearing a skirt or dress. While some women's bicycles continue to use this frame style, there is also a variation, the mixte, which splits the top tube laterally into two thinner top tubes that bypass the seat tube on each side and connect to the rear fork ends. The ease of stepping through is also appreciated by those with limited flexibility or other joint problems. Because of its persistent image as a "women's" bicycle, step-through frames are not common for larger frames.

Step-throughs were popular partly for practical reasons and partly for social mores of the day. For most of the history of bicycles' popularity women have worn long skirts, and the lower frame accommodated these better than the top-tube. Furthermore, it was considered "unladylike" for women to open their legs to mount and dismount—in more conservative times women who rode bicycles at all were vilified as immoral or immodest. These practices were akin to the older practice of riding horse sidesaddle.

Another style is the recumbent bicycle. These are inherently more aerodynamic than upright versions, as the rider may lean back onto a support and operate pedals that are on about the same level as the seat. The world's fastest bicycle is a recumbent bicycle but this type was banned from competition in 1934 by the Union Cycliste Internationale.

Historically, materials used in bicycles have followed a similar pattern as in aircraft, the goal being high strength and low weight. Since the late 1930s alloy steels have been used for frame and fork tubes in higher quality machines. By the 1980s aluminum welding techniques had improved to the point that aluminum tube could safely be used in place of steel. Since then aluminum alloy frames and other components have become popular due to their light weight, and most mid-range bikes are now principally aluminum alloy of some kind. More expensive bikes use carbon fibre due to its significantly lighter weight and profiling ability, allowing designers to make a bike both stiff and compliant by manipulating the lay-up. Virtually all professional racing bicycles now use carbon fibre frames, as they have the best strength to weight ratio. A typical modern carbon fiber frame can weigh less than 1 kg.

Other exotic frame materials include titanium and advanced alloys. Bamboo, a natural composite material with high strength-to-weight ratio and stiffness has been used for bicycles since 1894. Recent versions use bamboo for the primary frame with glued metal connections and parts, priced as exotic models.

Drivetrain and gearing
The drivetrain begins with pedals which rotate the cranks, which are held in axis by the bottom bracket. Most bicycles use a chain to transmit power to the rear wheel. A very small number of bicycles use a shaft drive to transmit power, or special belts. Hydraulic bicycle transmissions have been built, but they are currently inefficient and complex.

Since cyclists' legs are most efficient over a narrow range of pedaling speeds, or cadence, a variable gear ratio helps a cyclist to maintain an optimum pedalling speed while covering varied terrain. Some, mainly utility, bicycles use hub gears with between 3 and 14 ratios, but most use the generally more efficient dérailleur system, by which the chain is moved between different cogs called chainrings and sprockets to select a ratio. A dérailleur system normally has two dérailleurs, or mechs, one at the front to select the chainring and another at the back to select the sprocket. Most bikes have two or three chainrings, and from 5 to 11 sprockets on the back, with the number of theoretical gears calculated by multiplying front by back. In reality, many gears overlap or require the chain to run diagonally, so the number of usable gears is fewer.

An alternative to chaindrive is to use a synchronous belt. These are toothed and work much the same as a chain—popular with commuters and long distance cyclists they require little maintenance. They cannot be shifted across a cassette of sprockets, and are used either as single speed or with a hub gear.

Different gears and ranges of gears are appropriate for different people and styles of cycling. Multi-speed bicycles allow gear selection to suit the circumstances: a cyclist could use a high gear when cycling downhill, a medium gear when cycling on a flat road, and a low gear when cycling uphill. In a lower gear every turn of the pedals leads to fewer rotations of the rear wheel. This allows the energy required to move the same distance to be distributed over more pedal turns, reducing fatigue when riding uphill, with a heavy load, or against strong winds. A higher gear allows a cyclist to make fewer pedal turns to maintain a given speed, but with more effort per turn of the pedals.

With a chain drive transmission, a chainring attached to a crank drives the chain, which in turn rotates the rear wheel via the rear sprocket(s) (cassette or freewheel). There are four gearing options: two-speed hub gear integrated with chain ring, up to 3 chain rings, up to 12 sprockets, hub gear built into rear wheel (3-speed to 14-speed). The most common options are either a rear hub or multiple chain rings combined with multiple sprockets (other combinations of options are possible but less common).

Steering
The handlebars connect to the stem that connects to the fork that connects to the front wheel, and the whole assembly connects to the bike and rotates about the steering axis via the headset bearings. Three styles of handlebar are common. Upright handlebars, the norm in Europe and elsewhere until the 1970s, curve gently back toward the rider, offering a natural grip and comfortable upright position. Drop handlebars "drop" as they curve forward and down, offering the cyclist best braking power from a more aerodynamic "crouched" position, as well as more upright positions in which the hands grip the brake lever mounts, the forward curves, or the upper flat sections for increasingly upright postures. Mountain bikes generally feature a 'straight handlebar' or 'riser bar' with varying degrees of sweep backward and centimeters rise upwards, as well as wider widths which can provide better handling due to increased leverage against the wheel.

Seating
Saddles also vary with rider preference, from the cushioned ones favored by short-distance riders to narrower saddles which allow more room for leg swings. Comfort depends on riding position. With comfort bikes and hybrids, cyclists sit high over the seat, their weight directed down onto the saddle, such that a wider and more cushioned saddle is preferable. For racing bikes where the rider is bent over, weight is more evenly distributed between the handlebars and saddle, the hips are flexed, and a narrower and harder saddle is more efficient. Differing saddle designs exist for male and female cyclists, accommodating the genders' differing anatomies and sit bone width measurements, although bikes typically are sold with saddles most appropriate for men. Suspension seat posts and seat springs provide comfort by absorbing shock but can add to the overall weight of the bicycle.

A recumbent bicycle has a reclined chair-like seat that some riders find more comfortable than a saddle, especially riders who suffer from certain types of seat, back, neck, shoulder, or wrist pain. Recumbent bicycles may have either under-seat or over-seat steering.

Brakes
Bicycle brakes may be rim brakes, in which friction pads are compressed against the wheel rims; hub brakes, where the mechanism is contained within the wheel hub, or disc brakes, where pads act on a rotor attached to the hub. Most road bicycles use rim brakes, but some use disc brakes. Disc brakes are more common for mountain bikes, tandems and recumbent bicycles than on other types of bicycles, due to their increased power, coupled with an increased weight and complexity.

With hand-operated brakes, force is applied to brake levers mounted on the handlebars and transmitted via Bowden cables or hydraulic lines to the friction pads, which apply pressure to the braking surface, causing friction which slows the bicycle down. A rear hub brake may be either hand-operated or pedal-actuated, as in the back pedal coaster brakes which were popular in North America until the 1960s.

Track bicycles do not have brakes, because all riders ride in the same direction around a track which does not necessitate sharp deceleration. Track riders are still able to slow down because all track bicycles are fixed-gear, meaning that there is no freewheel. Without a freewheel, coasting is impossible, so when the rear wheel is moving, the cranks are moving. To slow down, the rider applies resistance to the pedals, acting as a braking system which can be as effective as a conventional rear wheel brake, but not as effective as a front wheel brake.

Suspension
Bicycle suspension refers to the system or systems used to suspend the rider and all or part of the bicycle. This serves two purposes: to keep the wheels in continuous contact with the ground, improving control, and to isolate the rider and luggage from jarring due to rough surfaces, improving comfort.

Bicycle suspensions are used primarily on mountain bicycles, but are also common on hybrid bicycles, as they can help deal with problematic vibration from poor surfaces. Suspension is especially important on recumbent bicycles, since while an upright bicycle rider can stand on the pedals to achieve some of the benefits of suspension, a recumbent rider cannot.

Basic mountain bicycles and hybrids usually have front suspension only, whilst more sophisticated ones also have rear suspension. Road bicycles tend to have no suspension.

Wheels and tires
The wheel axle fits into fork ends in the frame and fork. A pair of wheels may be called a wheelset, especially in the context of ready-built "off the shelf", performance-oriented wheels.

Tires vary enormously depending on their intended purpose. Road bicycles use tires 18 to 25 millimeters wide, most often completely smooth, or slick, and inflated to high pressure to roll fast on smooth surfaces. Off-road tires are usually between 38 and 64 mm wide, and have treads for gripping in muddy conditions or metal studs for ice.

Groupset
Groupset generally refers to all of the components that make up a bicycle excluding the bicycle frame, fork, stem, wheels, tires, and rider contact points, such as the saddle and handlebars.

Accessories

Some components, which are often optional accessories on sports bicycles, are standard features on utility bicycles to enhance their usefulness, comfort, safety and visibility. Fenders with spoilers (mudflaps) protect the cyclist and moving parts from spray when riding through wet areas. In some countries (e.g. Germany, UK), fenders are called mudguards. The chainguards protect clothes from oil on the chain while preventing clothing from being caught between the chain and crankset teeth. Kick stands keep bicycles upright when parked, and bike locks deter theft. Front-mounted baskets, front or rear luggage carriers or racks, and panniers mounted above either or both wheels can be used to carry equipment or cargo. Pegs can be fastened to one, or both of the wheel hubs to either help the rider perform certain tricks, or allow a place for extra riders to stand, or rest. Parents sometimes add rear-mounted child seats, an auxiliary saddle fitted to the crossbar, or both to transport children. Bicycles can also be fitted with a hitch to tow a trailer for carrying cargo, a child, or both.

Toe-clips and toestraps and clipless pedals help keep the foot locked in the proper pedal position and enable cyclists to pull and push the pedals. Technical accessories include cyclocomputers for measuring speed, distance, heart rate, GPS data etc. Other accessories include lights, reflectors, mirrors, racks, trailers, bags, water bottles and cages, and bell. Bicycle lights, reflectors, and helmets are required by law in some geographic regions depending on the legal code. It is more common to see bicycles with bottle generators, dynamos, lights, fenders, racks and bells in Europe. Bicyclists also have specialized form fitting and high visibility clothing.

Children's bicycles may be outfitted with cosmetic enhancements such as bike horns, streamers, and spoke beads. Training wheels are sometimes used when learning to ride, but a dedicated balance bike teaches independent riding more effectively.

Bicycle helmets can reduce injury in the event of a collision or accident, and a suitable helmet is legally required of riders in many jurisdictions. Helmets may be classified as an accessory or as an item of clothing.

Bike trainers are used to enable cyclists to cycle while the bike remains stationary. They are frequently used to warm up before races or indoors when riding conditions are unfavorable.

Standards
A number of formal and industry standards exist for bicycle components to help make spare parts exchangeable and to maintain a minimum product safety.

The International Organization for Standardization (ISO) has a special technical committee for cycles, TC149, that has the scope of "Standardization in the field of cycles, their components and accessories with particular reference to terminology, testing methods and requirements for performance and safety, and interchangeability".

The European Committee for Standardization (CEN) also has a specific Technical Committee, TC333, that defines European standards for cycles. Their mandate states that EN cycle standards shall harmonize with ISO standards. Some CEN cycle standards were developed before ISO published their standards, leading to strong European influences in this area. European cycle standards tend to describe minimum safety requirements, while ISO standards have historically harmonized parts geometry.

Maintenance and repair
Like all devices with mechanical moving parts, bicycles require a certain amount of regular maintenance and replacement of worn parts. A bicycle is relatively simple compared with a car, so some cyclists choose to do at least part of the maintenance themselves. Some components are easy to handle using relatively simple tools, while other components may require specialist manufacturer-dependent tools.

Many bicycle components are available at several different price/quality points; manufacturers generally try to keep all components on any particular bike at about the same quality level, though at the very cheap end of the market there may be some skimping on less obvious components (e.g. bottom bracket).
 * There are several hundred assisted-service Community Bicycle Organizations worldwide. At a Community Bicycle Organization, laypeople bring in bicycles needing repair or maintenance; volunteers teach them how to do the required steps.
 * Full service is available from bicycle mechanics at a local bike shop.
 * In areas where it is available, some cyclists purchase roadside assistance from companies such as the Better World Club or the American Automobile Association.

Maintenance
The most basic maintenance item is keeping the tires correctly inflated; this can make a noticeable difference as to how the bike feels to ride. Bicycle tires usually have a marking on the sidewall indicating the pressure appropriate for that tire. Bicycles use much higher pressures than cars: car tires are normally in the range of 30 to 40 psi, whereas bicycle tires are normally in the range of 60 to 100 psi.

Another basic maintenance item is regular lubrication of the chain and pivot points for derailleurs and brake components. Most of the bearings on a modern bike are sealed and grease-filled and require little or no attention; such bearings will usually last for 10000 miles or more. The crank bearings require periodic maintenance, which involves removing, cleaning and repacking with the correct grease.

The chain and the brake blocks are the components which wear out most quickly, so these need to be checked from time to time, typically every 500 miles or so. Most local bike shops will do such checks for free. Note that when a chain becomes badly worn it will also wear out the rear cogs/cassette and eventually the chain ring(s), so replacing a chain when only moderately worn will prolong the life of other components.

Over the longer term, tires do wear out, after 2000 to 5000 miles; a rash of punctures is often the most visible sign of a worn tire.

Repair
Very few bicycle components can actually be repaired; replacement of the failing component is the normal practice.

The most common roadside problem is a puncture. After removing the offending nail/tack/thorn/glass shard/etc., there are two approaches: either mend the puncture by the roadside, or replace the inner tube and then mend the puncture in the comfort of home. Some brands of tires are much more puncture-resistant than others, often incorporating one or more layers of Kevlar; the downside of such tires is that they may be heavier and/or more difficult to fit and remove.

Tools

There are specialized bicycle tools for use both in the shop and at the roadside. Many cyclists carry tool kits. These may include a tire patch kit (which, in turn, may contain any combination of a hand pump or CO2 pump, tire levers, spare tubes, self-adhesive patches, or tube-patching material, an adhesive, a piece of sandpaper or a metal grater (for roughening the tube surface to be patched) and sometimes even a block of French chalk), wrenches, hex keys, screwdrivers, and a chain tool. Special, thin wrenches are often required for maintaining various screw-fastened parts, specifically, the frequently lubricated ball-bearing "cones". There are also cycling-specific multi-tools that combine many of these implements into a single compact device. More specialized bicycle components may require more complex tools, including proprietary tools specific for a given manufacturer.

Social and historical aspects
The bicycle has had a considerable effect on human society, in both the cultural and industrial realms.

In daily life
Around the turn of the 20th century, bicycles reduced crowding in inner-city tenements by allowing workers to commute from more spacious dwellings in the suburbs. They also reduced dependence on horses. Bicycles allowed people to travel for leisure into the country, since bicycles were three times as energy efficient as walking and three to four times as fast.

In built-up cities around the world, urban planning uses cycling infrastructure like bikeways to reduce traffic congestion and air pollution. A number of cities around the world have implemented schemes known as bicycle sharing systems or community bicycle programs. The first of these was the White Bicycle plan in Amsterdam in 1965. It was followed by yellow bicycles in La Rochelle and green bicycles in Cambridge. These initiatives complement public transport systems and offer an alternative to motorized traffic to help reduce congestion and pollution. In Europe, especially in the Netherlands and parts of Germany and Denmark, bicycle commuting is common. In Copenhagen, a cyclists' organization runs a Cycling Embassy that promotes biking for commuting and sightseeing. The United Kingdom has a tax break scheme (IR 176) that allows employees to buy a new bicycle tax free to use for commuting.

In the Netherlands all train stations offer free bicycle parking, or a more secure parking place for a small fee, with the larger stations also offering bicycle repair shops. Cycling is so popular that the parking capacity may be exceeded, while in some places such as Delft the capacity is usually exceeded. In Trondheim in Norway, the Trampe bicycle lift has been developed to encourage cyclists by giving assistance on a steep hill. Buses in many cities have bicycle carriers mounted on the front.

There are towns in some countries where bicycle culture has been an integral part of the landscape for generations, even without much official support. That is the case of Ílhavo, in Portugal.

In cities where bicycles are not integrated into the public transportation system, commuters often use bicycles as elements of a mixed-mode commute, where the bike is used to travel to and from train stations or other forms of rapid transit. Some students who commute several miles drive a car from home to a campus parking lot, then ride a bicycle to class. Folding bicycles are useful in these scenarios, as they are less cumbersome when carried aboard. Los Angeles removed a small amount of seating on some trains to make more room for bicycles and wheel chairs.

Some US companies, notably in the tech sector, are developing both innovative cycle designs and cycle-friendliness in the workplace. Foursquare, whose CEO Dennis Crowley "pedaled to pitch meetings ... [when he] was raising money from venture capitalists" on a two-wheeler, chose a new location for its New York headquarters "based on where biking would be easy". Parking in the office was also integral to HQ planning. Mitchell Moss, who runs the Rudin Center for Transportation Policy & Management at New York University, said in 2012: "Biking has become the mode of choice for the educated high tech worker".

Bicycles offer an important mode of transport in many developing countries. Until recently, bicycles have been a staple of everyday life throughout Asian countries. They are the most frequently used method of transport for commuting to work, school, shopping, and life in general. In Europe, bicycles are commonly used. They also offer a degree of exercise to keep individuals healthy.

Bicycles are also celebrated in the visual arts. An example of this is the Bicycle Film Festival, a film festival hosted all around the world.

Female emancipation
The safety bicycle gave women unprecedented mobility, contributing to their emancipation in Western nations. As bicycles became safer and cheaper, more women had access to the personal freedom that bicycles embodied, and so the bicycle came to symbolize the New Woman of the late 19th century, especially in Britain and the United States. The bicycle craze in the 1890s also led to a movement for so-called rational dress, which helped liberate women from corsets and ankle-length skirts and other restrictive garments, substituting the then-shocking bloomers.

The bicycle was recognized by 19th-century feminists and suffragists as a "freedom machine" for women. American Susan B. Anthony said in a New York World interview on 2 February 1896: "I think it has done more to emancipate woman than any one thing in the world. I rejoice every time I see a woman ride by on a wheel. It gives her a feeling of self-reliance and independence the moment she takes her seat; and away she goes, the picture of untrammelled womanhood." In 1895 Frances Willard, the tightly laced president of the Woman's Christian Temperance Union, wrote A Wheel Within a Wheel: How I Learned to Ride the Bicycle, with Some Reflections by the Way, a 75-page illustrated memoir praising "Gladys", her bicycle, for its "gladdening effect" on her health and political optimism. Willard used a cycling metaphor to urge other suffragists to action.

In 1985, Georgena Terry started the first women-specific bicycle company. Her designs featured frame geometry and wheel sizes chosen to better fit women, with shorter top tubes and more suitable reach.

Economic implications

Bicycle manufacturing proved to be a training ground for other industries and led to the development of advanced metalworking techniques, both for the frames themselves and for special components such as ball bearings, washers, and sprockets. These techniques later enabled skilled metalworkers and mechanics to develop the components used in early automobiles and aircraft.

Wilbur and Orville Wright, a pair of businessmen, ran the Wright Cycle Company which designed, manufactured and sold their bicycles during the bike boom of the 1890s.

They also served to teach the industrial models later adopted, including mechanization and mass production (later copied and adopted by Ford and General Motors), vertical integration (also later copied and adopted by Ford), aggressive advertising (as much as 10% of all advertising in U.S. periodicals in 1898 was by bicycle makers), lobbying for better roads (which had the side benefit of acting as advertising, and of improving sales by providing more places to ride), all first practiced by Pope. In addition, bicycle makers adopted the annual model change (later derided as planned obsolescence, and usually credited to General Motors), which proved very successful.

Early bicycles were an example of conspicuous consumption, being adopted by the fashionable elites. In addition, by serving as a platform for accessories, which could ultimately cost more than the bicycle itself, it paved the way for the likes of the Barbie doll.

Bicycles helped create, or enhance, new kinds of businesses, such as bicycle messengers, traveling seamstresses, riding academies, and racing rinks. Their board tracks were later adapted to early motorcycle and automobile racing. There were a variety of new inventions, such as spoke tighteners, and specialized lights, socks and shoes, and even cameras, such as the Eastman Company's Poco. Probably the best known and most widely used of these inventions, adopted well beyond cycling, is Charles Bennett's Bike Web, which came to be called the jock strap.

They also presaged a move away from public transit that would explode with the introduction of the automobile.

J. K. Starley's company became the Rover Cycle Company Ltd. in the late 1890s, and then renamed the Rover Company when it started making cars. Morris Motors Limited (in Oxford) and Škoda also began in the bicycle business, as did the Wright brothers. Alistair Craig, whose company eventually emerged to become the engine manufacturers Ailsa Craig, also started from manufacturing bicycles, in Glasgow in March 1885.

In general, U.S. and European cycle manufacturers used to assemble cycles from their own frames and components made by other companies, although very large companies (such as Raleigh) used to make almost every part of a bicycle (including bottom brackets, axles, etc.) In recent years, those bicycle makers have greatly changed their methods of production. Now, almost none of them produce their own frames.

Many newer or smaller companies only design and market their products; the actual production is done by Asian companies. For example, some 60% of the world's bicycles are now being made in China. Despite this shift in production, as nations such as China and India become more wealthy, their own use of bicycles has declined due to the increasing affordability of cars and motorcycles. One of the major reasons for the proliferation of Chinese-made bicycles in foreign markets is the lower cost of labor in China.

In line with the European financial crisis, in Italy in 2011 the number of bicycle sales (1.75 million) just passed the number of new car sales.

Environmental impact

One of the profound economic implications of bicycle use is that it liberates the user from motor fuel consumption. (Ballantine, 1972) The bicycle is an inexpensive, fast, healthy and environmentally friendly mode of transport. Ivan Illich stated that bicycle use extended the usable physical environment for people, while alternatives such as cars and motorways degraded and confined people's environment and mobility. Currently, two billion bicycles are in use around the world. Children, students, professionals, laborers, civil servants and seniors are pedaling around their communities. They all experience the freedom and the natural opportunity for exercise that the bicycle easily provides. Bicycle also has lowest carbon intensity of travel.

Manufacturing
The global bicycle market is $61 billion in 2011. , 130 million bicycles were sold every year globally and 66% of them were made in China.

Legal requirements
Early in its development, as with automobiles, there were restrictions on the operation of bicycles. Along with advertising, and to gain free publicity, Albert A. Pope litigated on behalf of cyclists.

The 1968 Vienna Convention on Road Traffic of the United Nations considers a bicycle to be a vehicle, and a person controlling a bicycle (whether actually riding or not) is considered an operator. The traffic codes of many countries reflect these definitions and demand that a bicycle satisfy certain legal requirements before it can be used on public roads. In many jurisdictions, it is an offense to use a bicycle that is not in a roadworthy condition.

In some countries, bicycles must have functioning front and rear lights when ridden after dark.

Some countries require child and/or adult cyclists to wear helmets, as this may protect riders from head trauma. Countries which require adult cyclists to wear helmets include Spain, New Zealand and Australia. Mandatory helmet wearing is one of the most controversial topics in the cycling world, with proponents arguing that it reduces head injuries and thus is an acceptable requirement, while opponents argue that by making cycling seem more dangerous and cumbersome, it reduces cyclist numbers on the streets, creating an overall negative health effect (fewer people cycling for their own health, and the remaining cyclists being more exposed through a reversed safety in numbers effect).

Theft

Bicycles are popular targets for theft, due to their value and ease of resale. The number of bicycles stolen annually is difficult to quantify as a large number of crimes are not reported. Around 50% of the participants in the Montreal International Journal of Sustainable Transportation survey were subjected to a bicycle theft in their lifetime as active cyclists. Most bicycles have serial numbers that can be recorded to verify identity in case of theft.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Bicycle


text:
Biopolymer

Biopolymers are natural polymers produced by the cells of living organisms. Like other polymers, biopolymers consist of monomeric units that are covalently bonded in chains to form larger molecules. There are three main classes of biopolymers, classified according to the monomers used and the structure of the biopolymer formed: polynucleotides, polypeptides, and polysaccharides. The Polynucleotides, RNA and DNA, are long polymers of nucleotides. Polypeptides include proteins and shorter polymers of amino acids; some major examples include collagen, actin, and fibrin. Polysaccharides are linear or branched chains of sugar carbohydrates; examples include starch, cellulose, and alginate. Other examples of biopolymers include natural rubbers (polymers of isoprene), suberin and lignin (complex polyphenolic polymers), cutin and cutan (complex polymers of long-chain fatty acids), melanin, and polyhydroxyalkanoates (PHAs).

In addition to their many essential roles in living organisms, biopolymers have applications in many fields including the food industry, manufacturing, packaging, and biomedical engineering.

Biopolymers versus synthetic polymers
A major defining difference between biopolymers and synthetic polymers can be found in their structures. All polymers are made of repetitive units called monomers. Biopolymers often have a well-defined structure, though this is not a defining characteristic (example: lignocellulose): The exact chemical composition and the sequence in which these units are arranged is called the primary structure, in the case of proteins. Many biopolymers spontaneously fold into characteristic compact shapes (see also "protein folding" as well as secondary structure and tertiary structure), which determine their biological functions and depend in a complicated way on their primary structures. Structural biology is the study of the structural properties of biopolymers. In contrast, most synthetic polymers have much simpler and more random (or stochastic) structures. This fact leads to a molecular mass distribution that is missing in biopolymers. In fact, as their synthesis is controlled by a template-directed process in most in vivo systems, all biopolymers of a type (say one specific protein) are all alike: they all contain similar sequences and numbers of monomers and thus all have the same mass. This phenomenon is called monodispersity in contrast to the polydispersity encountered in synthetic polymers. As a result, biopolymers have a dispersity of 1.

Polypeptides
The convention for a polypeptide is to list its constituent amino acid residues as they occur from the amino terminus to the carboxylic acid terminus. The amino acid residues are always joined by peptide bonds. Protein, though used colloquially to refer to any polypeptide, refers to larger or fully functional forms and can consist of several polypeptide chains as well as single chains. Proteins can also be modified to include non-peptide components, such as saccharide chains and lipids.

Nucleic acids
The convention for a nucleic acid sequence is to list the nucleotides as they occur from the 5' end to the 3' end of the polymer chain, where 5' and 3' refer to the numbering of carbons around the ribose ring which participate in forming the phosphate diester linkages of the chain. Such a sequence is called the primary structure of the biopolymer.

Polysaccharides
Polysaccharides (sugar polymers) can be linear or branched and are typically joined with glycosidic bonds. The exact placement of the linkage can vary, and the orientation of the linking functional groups is also important, resulting in α- and β-glycosidic bonds with numbering definitive of the linking carbons' location in the ring. In addition, many saccharide units can undergo various chemical modifications, such as amination, and can even form parts of other molecules, such as glycoproteins.

Structural characterization
There are a number of biophysical techniques for determining sequence information. Protein sequence can be determined by Edman degradation, in which the N-terminal residues are hydrolyzed from the chain one at a time, derivatized, and then identified. Mass spectrometer techniques can also be used. Nucleic acid sequence can be determined using gel electrophoresis and capillary electrophoresis. Lastly, mechanical properties of these biopolymers can often be measured using optical tweezers or atomic force microscopy. Dual-polarization interferometry can be used to measure the conformational changes or self-assembly of these materials when stimulated by pH, temperature, ionic strength or other binding partners.

Common biopolymers
Collagen: Collagen is the primary structure of vertebrates and is the most abundant protein in mammals. Because of this, collagen is one of the most easily attainable biopolymers, and used for many research purposes. Because of its mechanical structure, collagen has high tensile strength and is a non-toxic, easily absorbable, biodegradable, and biocompatible material. Therefore, it has been used for many medical applications such as in treatment for tissue infection, drug delivery systems, and gene therapy.

Silk fibroin: Silk Fibroin (SF) is another protein rich biopolymer that can be obtained from different silkworm species, such as the mulberry worm Bombyx mori. In contrast to collagen, SF has a lower tensile strength but has strong adhesive properties due to its insoluble and fibrous protein composition. In recent studies, silk fibroin has been found to possess anticoagulation properties and platelet adhesion. Silk fibroin has been additionally found to support stem cell proliferation in vitro.

Gelatin: Gelatin is obtained from type I collagen consisting of cysteine, and produced by the partial hydrolysis of collagen from bones, tissues and skin of animals. There are two types of gelatin, Type A and Type B. Type A collagen is derived by acid hydrolysis of collagen and has 18.5% nitrogen. Type B is derived by alkaline hydrolysis containing 18% nitrogen and no amide groups. Elevated temperatures cause the gelatin to melts and exists as coils, whereas lower temperatures result in coil to helix transformation. Gelatin contains many functional groups like NH2, SH, and COOH which allow for gelatin to be modified using nanoparticles and biomolecules. Gelatin is an Extracellular Matrix protein which allows it to be applied for applications such as wound dressings, drug delivery and gene transfection.

Starch: Starch is an inexpensive biodegradable biopolymer and copious in supply. Nanofibers and microfibers can be added to the polymer matrix to increase the mechanical properties of starch improving elasticity and strength. Without the fibers, starch has poor mechanical properties due to its sensitivity to moisture. Starch being biodegradable and renewable is used for many applications including plastics and pharmaceutical tablets.

Cellulose: Cellulose is very structured with stacked chains that result in stability and strength. The strength and stability comes from the straighter shape of cellulose caused by glucose monomers joined together by glycogen bonds. The straight shape allows the molecules to pack closely. Cellulose is very common in application due to its abundant supply, its biocompatibility, and is environmentally friendly. Cellulose is used vastly in the form of nano-fibrils called nano-cellulose. Nano-cellulose presented at low concentrations produces a transparent gel material. This material can be used for biodegradable, homogeneous, dense films that are very useful in the biomedical field.

Alginate: Alginate is the most copious marine natural polymer derived from brown seaweed. Alginate biopolymer applications range from packaging, textile and food industry to biomedical and chemical engineering. The first ever application of alginate was in the form of wound dressing, where its gel-like and absorbent properties were discovered. When applied to wounds, alginate produces a protective gel layer that is optimal for healing and tissue regeneration, and keeps a stable temperature environment. Additionally, there have been developments with alginate as a drug delivery medium, as drug release rate can easily be manipulated due to a variety of alginate densities and fibrous composition.

Biopolymer applications
The applications of biopolymers can be categorized under two main fields, which differ due to their biomedical and industrial use.

Biomedical
Because one of the main purposes for biomedical engineering is to mimic body parts to sustain normal body functions, due to their biocompatible properties, biopolymers are used vastly for tissue engineering, medical devices and the pharmaceutical industry. Many biopolymers can be used for regenerative medicine, tissue engineering, drug delivery, and overall medical applications due to their mechanical properties. They provide characteristics like wound healing, and catalysis of bioactivity, and non-toxicity. Compared to synthetic polymers, which can present various disadvantages like immunogenic rejection and toxicity after degradation, many biopolymers are normally better with bodily integration as they also possess more complex structures, similar to the human body.

More specifically, polypeptides like collagen and silk, are biocompatible materials that are being used in ground-breaking research, as these are inexpensive and easily attainable materials. Gelatin polymer is often used on dressing wounds where it acts as an adhesive. Scaffolds and films with gelatin allow for the scaffolds to hold drugs and other nutrients that can be used to supply to a wound for healing.

As collagen is one of the more popular biopolymers used in biomedical science, here are some examples of their use:

Collagen based drug delivery systems: collagen films act like a barrier membrane and are used to treat tissue infections like infected corneal tissue or liver cancer. Collagen films have all been used for gene delivery carriers which can promote bone formation.

Collagen sponges: Collagen sponges are used as a dressing to treat burn victims and other serious wounds. Collagen based implants are used for cultured skin cells or drug carriers that are used for burn wounds and replacing skin.

Collagen as haemostat: When collagen interacts with platelets it causes a rapid coagulation of blood. This rapid coagulation produces a temporary framework so the fibrous stroma can be regenerated by host cells. Collagen based haemostat reduces blood loss in tissues and helps manage bleeding in organs such as the liver and spleen.

Chitosan is another popular biopolymer in biomedical research. Chitosan is derived from chitin, the main component in the exoskeleton of crustaceans and insects and the second most abundant biopolymer in the world. Chitosan has many excellent characteristics for biomedical science. Chitosan is biocompatible, it is highly bioactive, meaning it stimulates a beneficial response from the body, it can biodegrade which can eliminate a second surgery in implant applications, can form gels and films, and is selectively permeable. These properties allow for various biomedical applications of chitosan.

Chitosan as drug delivery: Chitosan is used mainly with drug targeting because it has potential to improve drug absorption and stability. In addition, chitosan conjugated with anticancer agents can also produce better anticancer effects by causing gradual release of free drug into cancerous tissue.

Chitosan as an anti-microbial agent: Chitosan is used to stop the growth of microorganisms. It performs antimicrobial functions in microorganisms like algae, fungi, bacteria, and gram-positive bacteria of different yeast species.

Chitosan composite for tissue engineering: Chitosan powder blended with alginate is used to form functional wound dressings. These dressings create a moist, biocompatible environment which aids in the healing process. This wound dressing is also biodegradable and has porous structures that allows cells to grow into the dressing. Furthermore, thiolated chitosans (see thiomers) are used for tissue engineering and wound healing, as these biopolymers are able to crosslink via disulfide bonds forming stable three-dimensional networks.

Industrial
Food: Biopolymers are being used in the food industry for things like packaging, edible encapsulation films and coating foods. Polylactic acid (PLA) is very common in the food industry due to is clear color and resistance to water. However, most polymers have a hydrophilic nature and start deteriorating when exposed to moisture. Biopolymers are also being used as edible films that encapsulate foods. These films can carry things like antioxidants, enzymes, probiotics, minerals, and vitamins. The food consumed encapsulated with the biopolymer film can supply these things to the body.

Packaging: The most common biopolymers used in packaging are polyhydroxyalkanoates (PHAs), polylactic acid (PLA), and starch. Starch and PLA are commercially available and biodegradable, making them a common choice for packaging. However, their barrier properties (either moisture-barrier or gas-barrier properties) and thermal properties are not ideal. Hydrophilic polymers are not water resistant and allow water to get through the packaging which can affect the contents of the package. Polyglycolic acid (PGA) is a biopolymer that has great barrier characteristics and is now being used to correct the barrier obstacles from PLA and starch.

Water purification: Chitosan has been used for water purification. It is used as a flocculant that only takes a few weeks or months rather than years to degrade in the environment. Chitosan purifies water by chelation. This is the process in which binding sites along the polymer chain bind with the metal ions in the water forming chelates. Chitosan has been shown to be an excellent candidate for use in storm and wastewater treatment.

As materials
Some biopolymers- such as PLA, naturally occurring zein, and poly-3-hydroxybutyrate can be used as plastics, replacing the need for polystyrene or polyethylene based plastics.

Some plastics are now referred to as being 'degradable', 'oxy-degradable' or 'UV-degradable'. This means that they break down when exposed to light or air, but these plastics are still primarily (as much as 98 per cent) oil-based and are not currently certified as 'biodegradable' under the European Union directive on Packaging and Packaging Waste (94/62/EC). Biopolymers will break down, and some are suitable for domestic composting.

Biopolymers (also called renewable polymers) are produced from biomass for use in the packaging industry. Biomass comes from crops such as sugar beet, potatoes, or wheat: when used to produce biopolymers, these are classified as non food crops. These can be converted in the following pathways:

Sugar beet > Glyconic acid > Polyglyconic acid

Starch > (fermentation) > Lactic acid > Polylactic acid (PLA)

Biomass > (fermentation) > Bioethanol > Ethene > Polyethylene

Many types of packaging can be made from biopolymers: food trays, blown starch pellets for shipping fragile goods, thin films for wrapping.

Environmental impacts
Biopolymers can be sustainable, carbon neutral and are always renewable, because they are made from plant or animal materials which can be grown indefinitely. Since these materials come from agricultural crops, their use could create a sustainable industry. In contrast, the feedstocks for polymers derived from petrochemicals will eventually deplete. In addition, biopolymers have the potential to cut carbon emissions and reduce CO2 quantities in the atmosphere: this is because the CO2 released when they degrade can be reabsorbed by crops grown to replace them: this makes them close to carbon neutral.

Almost all biopolymers are biodegradable in the natural environment: they are broken down into CO2 and water by microorganisms. These biodegradable biopolymers are also compostable: they can be put into an industrial composting process and will break down by 90% within six months. Biopolymers that do this can be marked with a 'compostable' symbol, under European Standard EN 13432 (2000). Packaging marked with this symbol can be put into industrial composting processes and will break down within six months or less. An example of a compostable polymer is PLA film under 20μm thick: films which are thicker than that do not qualify as compostable, even though they are "biodegradable". In Europe there is a home composting standard and associated logo that enables consumers to identify and dispose of packaging in their compost heap.

title: Biopolymer