Fixed-gear bicycle

From Wikipedia, the free encyclopedia

Jump to: navigation, search
A fixed-gear bicycle
An 18 tooth cog that attaches to the rear hub of fixed-gear bike
Track sprockets are typically attached and removed from the hub by screwing them with a chain whip. This tool also has a lockring spanner for securing a reverse threaded lockring against the sprocket.

A fixed-gear bicycle or fixed wheel bicycle is a bicycle without the ability to coast. The sprocket is screwed directly on to the hub and there is no freewheel mechanism. A reverse-threaded lockring is usually fitted to prevent the sprocket from unscrewing.[1] Whenever the rear wheel is turning, the pedals turn in the same direction.[2] By resisting the rotation of the pedals, a rider can slow the bike to a stop without the aid of a brake.[1] Stopping is sometimes known as "skidding" in the fixed gear world. Skidding occurs when the rider opposes the pedals' movement hard enough to halt the rear wheel's rotation. A fixed gear bicycle can also be ridden in reverse.

Most fixed gear bicycles only have one gear ratio. 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.[3] 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).

In the past Sturmey Archer made a fixed multi speed hub gear, the model ASC, allowing the rider to change gear while riding.[4] Its successor company, SunRace Sturmey-Archer, plans to produce a modern equivalent, the S3X, in the near future[5].

Fixed gear bikes are alternatively known as fixie bikes, or simply fixies.

Contents

[edit] Uses

A fixed/freewheel rear hub

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.[6]

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 pedalling style.[7] In the UK until the 1950s it was common for riders to use a fixed wheel for time trials.[8][9] The fixed wheel was also commonly used, and continues to be used in the end of season hill climb races in the autumn.[10][11] 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.[12][13] By the 1960s, multi-gear derailleurs had become the norm and riding fixed wheel on the road declined over the next few decades.[14] Recent years have seen renewed interest and increased popularity of fixed wheel cycling in the UK.[15]

In urban North America fixed gear bicycles have achieved tremendous popularity, with the rise of discernible regional aesthetic preferences for finish and design details.[16] The rise in popularity of fixed-gear bicycles in the mid-2000s, complete with adaptations such as spoke cards, is attributed to bicycle messengers. [17]

Dedicated fixed-gear road bicycles are being produced in greater numbers by established bicycle manufacturers. They are generally low in price,[18] and characterized by a more forgiving, slacker road geometry, as opposed to the steeper, more aggressive geometry of track bicycles.[19]

Fixed-gear bicycles are also used in cycle ball 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.[20]

A subset of fixed gear track bike riding is emerging from urban youth, often associated with hipsters, with roots in modern skateboarding and Freestyle BMX. Track bike tricks are largely unexplored and like the sport's precursors, have an overwhelming appreciation for style and originality. "Fixies" are also used for increased performance.[citation needed]

[edit] Advantages and disadvantages

Fixed gear bicycles are ridden by cyclists for many reasons, such as their light weight, simplicity, low maintenance.[21]

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.[22] In slippery conditions some riders prefer to ride fixed because the transmission gives feedback on back tire grip.[23]

Descending is more difficult as the rider must spin the cranks at a very high speed (sometimes at 150rpm 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 pedaling performance on any type of bicycle.[24]

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.[25]

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 is not possible, this can lead to anything from a 'kick' to the trailing leg, up to a loss of control of the bicycle.[citation needed]

[edit] Brakes

Because it is possible to slow down or stop a fixed-gear bike by resisting the turning pedals, some riders think brakes are not strictly necessary. However, if the rider of a fixed-gear bike only has a rear wheel brake, the maximal deceleration is significantly lower than on a bike equipped with both a front and rear brake.[26] 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). Some fixed gear riders only equip their bike with a front brake.

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 pedals, thus stopping the drivetrain and rear wheel, while applying his or her body weight in opposition to the normal rotation of the pedals. 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.[27][28] As with the technique of resisting the pedals, 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.

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.[29]

Other riders dismiss riding on roads without brakes as an unnecessary affectation, based on image rather than what is practical when riding a bicycle.[30] Furthermore, riding brakeless may jeopardize the chances of a successful insurance claim in the event of an accident and, in some jurisdictions (including the UK[citation needed] ), is against the law.[31] It also greatly increases stress on the knees which can lead to injury. Some will have one (usually front) brake for emergencies, for descending steep hills, for safety in the event of a broken or derailed chain, to comply with traffic law, or to prevent knee injury. Others will have two brakes for better control in hills, for slippery road conditions, or for use in the event of a broken or thrown chain, broken brake or brake cable.

In the United States, fixed-gear bikes without hand brakes are illegal in many places. Fixed-gear sidewalk bikes -- the U.S. Consumer Product Safety Commission's term for one with a seat height of no more than 25 inches adjusted to its highest position, and no free wheel -- are not required to have brakes if they bear a permanent label visible from 10 feet displaying the words "No Brakes." The same label must be displayed prominently on promotional display material and shipping cartons.[citation needed]

In the 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'[verification needed] . It is commonly thought that a front brake and a fixed rear wheel satisfies this requirement.

[edit] U.S. and British English usage

"Fixed gear" is the standard term in the U.S., whilst "fixed wheel" is used in the UK.[32][33] The confusion comes about because "fixed", "gear" and "wheel" can have more than one meaning in this context. "Fixed" can mean not able to freewheel (coast), it can also mean not variable. "Gear" can refer to the sprocket or to a gear ratio. In the US, "fixed-gear" is used to mean the gear (sprocket) is attached to the hub without a freewheel. In the UK, "fixed-wheel" is the normal term, meaning the opposite of freewheel, whereas fixed gear usually means one gear (gear ratio). See also single-speed bicycle.

[edit] Conversion

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.[34]

A horizontal dropout on a steel frame road bicycle converted to a single-speed. The non-replaceable derailleur hanger (below the axle) and an eyelet (above the axle) for mounting a fender or rack are now unused.

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.[35] 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 a slight 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 cog.

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

[edit] Competition

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.

[edit] See also

[edit] Notes

  1. ^ a b "Why We Love Fixed-Gears and Single-Speeds". Circle A Cycles. http://www.circleacycles.com/riding_single.php. Retrieved on 2007-08-12. 
  2. ^ "What is a Fixed Gear?". Commute By Bike. 2005-05-31. http://commutebybike.com/2005/05/31/what-is-a-fixed-gear/. Retrieved on 2007-08-12. 
  3. ^ Shaver, Bob (2004-09-28). "Bicycle Derailleurs". Patent Pending Blog. http://patentpending.blogs.com/patent_pending_blog/2004/09/bicycle_deraill.html. Retrieved on 2007-08-12. 
  4. ^ Brown, Sheldon. "The Sturmey-Archer ASC Three-Speed Fixed-Gear Hub". Harris Cyclery. http://sheldonbrown.com/asc.html. Retrieved on 2007-08-12. 
  5. ^ "SunRace blog". SunRace Sturmey-Archer. 2008-09-02. http://www.sunrace-sturmeyarcher.blogspot.com/. Retrieved on 2008-11-12. 
  6. ^ Goode, Greg (2003). "Fixed-Gear vs. Track Bikes". Old Skool Track. http://www.oldskooltrack.com/files/fixed_track.frame.html. Retrieved on 2007-08-12. 
  7. ^ 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"...".
  8. ^ 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.
  9. ^ [1] Modern fixed gear bicycles are credited to Gregory Ferris. [2] [3] [4] Various accounts of fixed wheel time trailing in the UK.
  10. ^ [5] "Fixed wheel" bike used to win the 2003 British national hill climb championship.
  11. ^ [6] Account of the 1987 British national hill climb championship.
  12. ^ Rotrax
  13. ^ [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.
  14. ^ Stone, Hilary. "Sturmey Archer ASC 3-speed fixed-wheel hub gear". Classic Lightweights. http://www.classiclightweights.co.uk/designs/hsasc.html. Retrieved on 2007-09-11. 
  15. ^ Ward, Simon; Clune, Arthur; Curtin, John; "others" (September 12, 2007). "Going Fixed - The Art of Cycling without Gears". fixedwheel.org. http://www.deepwater.uklinux.net/www.fixedwheel.org.uk/howto/. Retrieved on 2007-09-11. 
  16. ^ Hannah Karp (2006-06-08). "More riders trying 'fixie' bikes with one gear, many risks" (HTML). Sign On Sand Diego (The Union-Tribune). http://www.signonsandiego.com/uniontrib/20060708/news_lz1n8read.html. Retrieved on 2007-08-12. 
  17. ^ Ryan, Singel. "Fixed-Gear Bikes an Urban Fixture". Wired Magazine. Retrieved on August 31, 2008.
  18. ^ Jim Miller (2006-06-18). "Quest for a Fixed Gear" (HTML). Washington Post. http://www.washingtonpost.com/wp-dyn/content/article/2006/06/15/AR2006061501749.html. Retrieved on 2007-08-12. 
  19. ^ "Buyers' Guide To "Fixie" Bicycles!" (HTML). Cyclesmith. http://cyclesmith.ca/page.cfm?PageID=285. Retrieved on 2007-08-12. 
  20. ^ Lucas Wisenthal. "Bare bones biking". Montreal Mirror 23 (2). http://www.montrealmirror.com/2007/062807/news3.html. Retrieved on 2007-08-12. 
  21. ^ Singel, Ryan (2007-04-07). "Fixed-Gear Bikes an Urban Fixture". http://www.wired.com/culture/lifestyle/news/2005/04/67149. Retrieved on 2007-12-23. 
  22. ^ Larkin, Scott (2004). "the fixed gear purist cult mentality thing". http://www.oldskooltrack.com/files/cult.mentality.frame.html. 
  23. ^ Brown, Sheldon (1995-12-26), Fixed Gear Bicycles for the Road, http://www.sheldonbrown.com/fixeda.html 
  24. ^ Seaton, Matt. "Fixed Idea". Rouleur. http://www.rouleur.cc/index.php?option=com_content&view=article&id=50&Itemid=87.  Selected extract.
  25. ^ "About Fixed Gears". Old Skool Track. http://www.oldskooltrack.com/files/aboutfixed.frame.html. Retrieved on 2007-09-11. 
  26. ^ Stevenson, John (August 8, 2006). "Fixies outlawed?". Cycling News.com. http://www.cyclingnews.com/tech.php?id=tech/2006/news/08-04. Retrieved on 2007-09-11. 
  27. ^ Brown, Sheldon. "Fixed Gear for the Road: Skip Stops". Harris Cyclery. http://www.sheldonbrown.com/fixed.html#skip. Retrieved on 2007-09-11. 
  28. ^ Chidley, 'Buffalo' Bill (October 1993). "Track bikes at CMC 1993". Cycling Plus. http://www.movingtargetzine.com/article/track-bikes-at-cmc-1993. Retrieved on 2007-09-19. 
  29. ^ Wisenthal, Lucas (June 28, 2007). "Bare bones biking". Montreal Mirror. http://www.montrealmirror.com/2007/062807/news3.html. Retrieved on 2007-09-11. 
  30. ^ Churchill, Paul (2005-10-13). "Are Brakes For Flakes?". Moving Target. http://www.movingtargetzine.com/article/are-brakes-for-flakes. Retrieved on 2007-09-16. 
  31. ^ Colegrove, Sara W.. "Do You Ride A Fixed Gear Bike? You May Be Breaking The Law". League of Michigan Bicyclist. http://www.lmb.org/pages/Resources/Legal/DoYouRideAFixedGearBike.htm. Retrieved on 2007-09-11. 
  32. ^ "Time Trial Regulations". Cycling Time Trials. http://www.cyclingtimetrials.org.uk/regulations.asp. Retrieved on 2007-09-11. "Bicycles with a fixed wheel shall have a left hand threaded locking device securing the fixed sprocket. Similarly, tricycles with a fixed wheel shall have a suitable locking device or alternatively shall include an integral system as part of the design. Machines with fixed wheel require only a brake operating on the front wheel(s)." 
  33. ^ "National Hill Climb Championship: King Paul Grabs Title on the Chimney". http://www.paulcurran.ndo.co.uk/Articles/1987/871025-NationalHillClimb.html. Retrieved on 2007-09-11. 
  34. ^ Sheldon Brown's Bicycle Glossary Tp-Tz
  35. ^ Brown, Sheldon. "Fixed Gear Conversions". http://sheldonbrown.com/fixed-conversion.html. Retrieved on 2007-09-11. 
v • d • e
Gears
Gear systems
Gear shapes
Geartooth profiles
Gear mechanics
Examples
In Bicycles: Cogset • Derailleur gears • Hub gear • Shaft-driven bicycle • Sprocket
In Horology: Wheel train
See also
Retrieved from "http://en.wikipedia.org/wiki/Fixed-gear_bicycle"
Personal tools