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File:Fixed-gear-bike.jpg
File:Fixed gear cog.jpg
File:Track sprocket tool by Bruce McAdam.jpg
In the UK and Australia, "fixed-wheel" is the normal term for the subject of this article - meaning the opposite of freewheel, and "fixed-gear" refers to a single-speed bicycle.

A fixed-gear bicycle (or fixed wheel bicycle) is a bicycle that has no freewheel, meaning it cannot coast — the pedals are always in motion when the bicycle is moving. The sprocket is screwed directly onto the hub. When the rear wheel turns, the pedals turn in the same direction.[1] This allows a cyclist to stop without using a brake, by resisting the rotation of the cranks, and also to ride in reverse.

Track cycling in a velodrome has always used fixed-gear track bikes, but fixed-gear bicycles are now used on the road,[2] a trend generally seen as being led by bicycle messengers.[3]

Most fixed gear bicycles have just one gear ratio.

Uses Edit

File:Fixed-gear-cogs.jpg

The track bicycle is a form of fixed-gear bicycle used for track cycling in a velodrome. But since a "fixed-gear bicycle" is just a bicycle without a freewheel, a fixed-gear bicycle can be any type of bicycle.[2]

Traditionally, some road racing and club cyclists used a fixed wheel bicycle for training during the winter months, generally using a relatively low gear ratio, believed to help develop a good pedaling style.[4] In the UK until the 1950s it was common for riders to use a fixed wheel for time trials.[5][6] The fixed wheel was also commonly used, and continues to be used in the end of season hill climb races in the autumn.[7][8] A typical clubmen's fixed wheel machine would have been a "road-path" or "road/track" cycle. In the era when most riders only had one cycle, the same bike when stripped down and fitted with racing wheels was used for road time trials and track racing, and when fitted with mudguards (fenders) and a bag it was used for club runs, touring and winter training.[9][10] By the 1960s, multi-gear derailleurs had become the norm and riding fixed wheel on the road declined over the next few decades.[11] Recent years have seen renewed interest and increased popularity of fixed wheel cycling.[12]

In urban North America fixed gear bicycles have achieved tremendous popularity, with the rise of discernible regional aesthetic preferences for finish and design details.[13] The rise in popularity of fixed-gear bicycles in the mid-2000s, complete with adaptations such as spoke cards, is attributed to bicycle messengers.[3]

Dedicated fixed-gear road bicycles are being produced in greater numbers by established bicycle manufacturers. They are generally low in price,[14] and characterized by a very forgiving, slack road geometry, as opposed to the steep,aggressive geometry of track bicycles.[15]

Fixed-gear bicycles are also used in cycle ball, bike polo and artistic cycling.

A fixed-gear bicycle is particularly well suited for track stands, a manoeuver in which the bicycle can be held stationary, balanced upright with the rider's feet on the pedals.[16]

GearsEdit

Although most fixed-gear bikes are also single-speed, this is not necessarily the case.

In the past Sturmey Archer made a fixed multi-speed hub gear, the model ASC, allowing the rider to change gear while riding.[17] Its successor company, SunRace Sturmey-Archer, plans to produce a modern equivalent, the S3X, in the near future[18].

Some have a sprocket on each side of the rear hub, giving the rider a choice of two different gear ratios. Such a hub may have a fixed gear on each side (double-fixed) or a fixed gear on one side and a freewheel on the other (fixed-free) also known as a flip-flop hub. To change gear, it is necessary to remove, reverse and refit the rear wheel.[19] Typically, the number of teeth on the sprockets will differ by one or two, for example 19 teeth on one side and 17 on the other, making the latter gear some 11 or 12% higher than the former (for the same chainring).

There is also a possibility to install two chainrings and two sprockets (or a double sprocket like a fixed Surly Dingle Cog or White Industries DOS ENO freewheel; cassete conversions might also work). This will let you choose between two gear ratios. For example, with 51-49 chainrings and 17-19 sprockets you may have 51/17=3 and 49/19=~2.6 ratios. The advantage of such a setup is that you actually have two gears but you neither need a chain tensioner, nor have you to change the length of the chain. This is due to the fact that the sum of teeth on the two ratios is the same: 51+17=49+19. To switch gears you have to loosen the wheel and then tighten it back.

Advantages and disadvantagesEdit

Fixed gear bicycles are ridden by cyclists for many reasons, such as their light weight, simplicity, and low maintenance.[20]

Many people who ride fixed-gear bicycles simply find it more enjoyable than or as an alternative to riding bikes with freewheels. Although the bike has only one gear, the lighter weight of a fixed-gear bike over its multi-speed freewheel equivalent can provide increased performance in some conditions.[21] In slippery conditions some riders prefer to ride fixed because the transmission gives feedback on back tire grip.[22]

Descending is more difficult as the rider must spin the cranks at a very high speed (sometimes at 170 rpm or more), or use the brake(s) to slow down. Nevertheless, the enforced fast spin when descending is said to increase "souplesse" (a French word meaning suppleness or flexibility, usually referring to the human body), which improves pedalling performance on any type of bicycle.[23]

Riding fixed is generally considered to encourage a more effective pedaling style, which translates into greater efficiency and power when used on a bicycle fitted with a freewheel.[24]

When first riding a fixed gear, a cyclist used to a freewheel has a tendency to try to coast now and again, particularly when approaching corners or obstacles. Since freewheeling, or coasting, is not possible, this can lead to anything from a 'kick' to the trailing leg, up to a loss of control of the bicycle.

Riding at speed round corners can be difficult for the novice rider, as the pedals can strike the road, resulting in a possible loss of control. Riders of freewheeling bicycles usually instinctively equalise the pedal height when making such turns.[citation needed]

Brakeless Edit

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Some fixed-gear riders think brakes are not strictly necessary, and brakeless fixed riding has an almost cult status in some places, based on the perception by some riders of the experience of riding in a state of intense concentration or 'flow' where brakes are thought not to be needed.[25]

Other riders dismiss riding on roads without brakes as an unnecessary affectation, based on image rather than what is practical when riding a bicycle.[26] Furthermore, riding brakeless may jeopardize the chances of a successful insurance claim in the event of an accident and, in some jurisdictions is against the law.[27]

Physics and techniqueEdit

It is possible to slow down or stop a fixed-gear bike by resisting the turning cranks, and a rider can also lock the rear wheel and skid to slow down or completely stop on a fixed-gear bicycle, a maneuver sometimes known as a skid stop. It is initiated by unweighting the rear wheel while in motion by shifting the rider's weight slightly forward and pulling up on the pedals using clipless pedals or toe clips and straps. The rider then stops turning the cranks, thus stopping the drivetrain and rear wheel, while applying his or her body weight in opposition to the normal rotation of the cranks. This action causes rear wheel to skid, which acts to slow the bike. The skid can be held until the bicycle stops or until the rider desires to continue pedalling again at a slower speed. The technique requires a little practice and using it while cornering is generally considered dangerous.[28][29] As with the technique of resisting the cranks, the maximal deceleration of this method of slowing is also significantly lower than using a front brake. A wet surface further reduces the effectiveness of this method, almost to the point of not reducing speed at all.

On any bike with only rear wheel braking, the maximal deceleration is significantly lower than on a bike equipped with a front brake.[30] As a vehicle brakes, weight is transferred towards the front wheel and away from the rear wheel, decreasing the amount of grip the rear wheel has. Shifting the rider's weight aft will increase rear wheel braking efficiency, but normally the front wheel might provide 70% or more of the braking power when braking hard (see Weight transfer).

Knee healthEdit

Braking by resisting the turning cranks greatly increases stress on the knees which can lead to injury.[28]

LegalityEdit

United States - The use of any bike without brakes on public roads is illegal in many places, but the wording is often something along the lines of "...must be equipped with a brake that will enable the person operating the cycle to make the braked wheels skid on dry, level and clean pavement..."[31] which some have argued allows the use of the legs and gears[32]. The retail sale of bikes without brakes is banned by the U.S. Consumer Product Safety Commission[33] - but with an exception for the "track bicycle" (...a bicycle designed and intended for sale as a competitive machine having tubular tires, single crank-to-wheel ratio, and no free-wheeling feature between the rear wheel and the crank....[34] ).

UK - The Pedal Cycles Construction and Use Regulations 1983 requires that pedal cycles "with a saddle height over 635 mm to have two independent braking systems, with one acting on the front wheel(s) and one on the rear". It is commonly thought that a front brake and a fixed rear wheel satisfies this requirement [35].

Germany - The Amtsgericht (local court) Bonn declared the fixed gear system as a brake system compliant with the German StVZO .[36]

Australia - In every state, bicycles are regarded as vehicles under the Road Rules. By law, a bike is required to have at least one functioning brake.[37]

Conversion Edit

Many companies sell bicycle frames designed specifically for use with fixed-gear hubs. A fixed-gear or track-bike hub includes special threads for a lockring that tightens in the opposite (counter-clockwise) direction compared with the sprocket. This ensures that the sprocket cannot unscrew when the rider "backpedals" while braking.[38]

File:Rear dropout.JPG

For a variety of reasons, many cyclists choose to convert freewheel bicycles to fixed gear. Frames with horizontal dropouts will be straightforward to convert, frames with vertical dropouts less so.[39] One method is to simply replace the rear wheel with a wheel that has a track/fixed hub. Another is to use a hub designed to be used with a threaded multi-speed freewheel. Such a hub will only have the normal right-handed threads for the sprocket and not the reverse threads for the lockrings used on track/fixed hubs. There is the possibility that the sprocket on a hub without a lockring will unscrew while back pedalling. Even if a bottom bracket lockring is threaded onto the hub along with a track sprocket, because the bottom-bracket lockring is not reverse threaded, the possibility still exists that both the sprocket and locknut can unscrew. Therefore it is recommended to have both front and rear brakes on a fixed-gear bicycle using a converted freewheel hub in case the sprocket unscrews while back pedaling. It is also advisable to use a thread sealer such as manufactured by Loctite for the sprocket and bottom bracket lockring. The rotafix (or "frame whipping") method may be helpful to securely install the sprocket.

Bicycles with vertical dropouts and no derailleur require some way to adjust chain tension. Most bicycles with horizontal dropouts can be tensioned by moving the wheel forward or backward in the dropouts. Bicycles with vertical dropouts can also be converted with some additional hardware. Possibilities include:

  • An eccentric hub or bottom bracket allows the off center axle or bottom bracket spindle to pivot and change the chain tension.
  • A "Ghost" or "floating" chainring. An additional chainring placed in the drive train between the driving chainring and sprocket. The top of the chain moves it forward at the same speed that the bottom of the chain moves it backwards, giving the appearance that it is floating in the chain.
  • A "Magic gear". With some math you can calculate a gearing ratio to fit a taut chain between the rear dropout and bottom bracket. Also, using a chain half link and slightly filing the dropouts to increase the width of the slot will increase the chances of finding a "magic gear."

Separate chain tensioning devices such as the type which are attached to the dropout gear hanger (commonly used on single speed mountain bikes) cannot be used because they will be damaged as soon as the lower part of the chain becomes tight.

Additional adjustments or modification may be needed to ensure a good chainline. The chain should run straight from the chainring to the sprocket, therefore both need to be the same distance away from the bicycle's centerline. Matched groupsets of track components are normally designed to give a chainline of 42 mm, but conversions using road or mountain bike cranksets often use more chainline. Some hubs, such as White Industries' ENO, or the British Goldtec track hub, are better suited to this task as they have a chainline greater than standard. Failure to achieve good chainline will at best lead to a noisy chain and increased wear, and at worst can throw the chain off the sprocket. This can result in rear wheel lockup and a wrecked frame if the chain falls between the rear sprocket and the spokes. Chainline can be adjusted in a number of ways, which may be used in combination with each other:

  • Obtaining a bottom bracket with a different spindle length, to move the chainring inboard or outboard
  • Choosing a bottom bracket with two lockrings, which gives fine adjustment of chainring position
  • Respacing and redishing the rear wheel, where permitted by the hub design
  • Placing thin spacers under the bottom bracket's right-hand cup (Sturmey-Archer make a suitable 1/16" spacer) to move the chainring outboard
  • Placing thin spacers between the chainring and its stack bolts to move it inboard (if the chainring is on the inside of the crank spider) or outboard (if the ring is on the outside of the spider)
  • Placing thin spacers between the hub shoulder and the rear sprocket - only recommended in the case of a freewheel-threaded hub, which has sufficiently deep threads for this

Competition Edit

There are many forms of competition using a fixed gear bike, most of the competitions being track races. Bike messengers and other urban riders may ride fixed gear bicycles in alleycat races, including New York City's famous fixed-gear-only race Monstertrack alleycat. There are also events based on messenger racing such as Mixpression which has been held 9 times in Tokyo. But recently with the widespread popularity and advancement of fixed gear bikes, trick competitions have also become a form of event at many of the more recent alleycats. Some other competitions are games of foot down and bike polo.

In 2006, Adventures for the Cure made a documentary film on riding across the United States on fixed gears; they repeated this feat as a 4-man team at the 2008 Race Across America.

See also Edit

NotesEdit

  1. Template:Cite web
  2. 2.0 2.1 Template:Cite web
  3. 3.0 3.1 Ryan, Singel. "Fixed-Gear Bikes an Urban Fixture". Wired Magazine. Retrieved on August 31, 2008.
  4. The Complete Cycle Sport Guide, Peter Konopka, 1982, EP Publishing, pages 70-71: "Top class riders spend the whole winter on such small gears (42x17 or 18)...to get good pedal training some adopt a "fixed wheel"...".
  5. The 1959 British 25 mile time trial championship was won by Alf Engers with a competition record of 55 min 11 sec, riding an 84 inch fixed wheel.
  6. [1] Modern fixed gear bicycles are credited to Gregory Ferris. [2] [3] [4] Various accounts of fixed wheel time trailing in the UK.
  7. [5] "Fixed wheel" bike used to win the 2003 British national hill climb championship.
  8. [6] Account of the 1987 British national hill climb championship.
  9. Rotrax
  10. [7] [8] [9] Examples of fixed wheel cycles of the period, including the bike that Ray Booty used for the first sub-four-hour "out and back" 100 mile time trial in 1956.
  11. Template:Cite web
  12. Template:Cite web
  13. Template:Cite news
  14. Template:Cite news
  15. Template:Cite web
  16. Lucas Wisenthal. "Bare bones biking". Montreal Mirror 23 (2). Archived from the original on 2007-10-31. http://web.archive.org/20071031053741/www.montrealmirror.com/2007/062807/news3.html. Retrieved 2007-08-12. 
  17. Template:Cite web
  18. Template:Cite web
  19. Template:Cite web
  20. Template:Cite web
  21. Template:Cite web
  22. [citation needed]
  23. Template:Cite web Selected extract.
  24. Template:Cite web
  25. Template:Cite web
  26. Template:Cite web
  27. Template:Cite web
  28. 28.0 28.1 Template:Cite web
  29. Template:Citeweb
  30. Template:Cite web
  31. [10]
  32. [11]
  33. [12]
  34. [13]
  35. Template:Cite web
  36. Gericht erkennt Fixie-Antrieb als Bremse an- Der Spiegel 06Aug09.
  37. [14] NSW Road Traffic Authority
  38. Sheldon Brown's Bicycle Glossary Tp-Tz
  39. Template:Cite web

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