Biopace

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Biopace triple crankset Biopacemtb.jpg
Biopace triple crankset
The Biopace logo on a chainring Biopacesticker.jpg
The Biopace logo on a chainring

Biopace is a tradename for a type of ovoid bicycle chain ring manufactured by Shimano from 1983 to 1993 [1] [2] The design was intended to help overcome the "dead zone" where the crank arms are vertical and riders have little mechanical advantage. [3]

Shimano, Inc. is a Japanese multinational manufacturer of cycling components, fishing tackle and rowing equipment. It produced golf supplies until 2005 and snowboarding gear until 2008. Headquartered in Sakai, Japan, the company has 32 consolidated subsidiaries and 11 unconsolidated subsidiaries. Shimano's primary manufacturing plants are in Kunshan, China; Malaysia; and Singapore.

Crankset bb set

The crankset or chainset, is the component of a bicycle drivetrain that converts the reciprocating motion of the rider's legs into rotational motion used to drive the chain or belt, which in turn drives the rear wheel. It consists of one or more sprockets, also called chainrings or chainwheels attached to the cranks, arms, or crankarms to which the pedals attach. It is connected to the rider by the pedals, to the bicycle frame by the bottom bracket, and to the rear sprocket, cassette or freewheel via the chain.

Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. The device preserves the input power and simply trades off forces against movement to obtain a desired amplification in the output force. The model for this is the law of the lever. Machine components designed to manage forces and movement in this way are called mechanisms. An ideal mechanism transmits power without adding to or subtracting from it. This means the ideal mechanism does not include a power source, is frictionless, and is constructed from rigid bodies that do not deflect or wear. The performance of a real system relative to this ideal is expressed in terms of efficiency factors that take into account departures from the ideal.

Biopace chainrings have a reduced chainring diameter coinciding with the cranks being horizontal. This is supposed to smooth the pedaling action, allowing the rider's feet to carry more momentum through the power stroke, and having it smoothly removed at the bottom of the stroke rather than encouraging riders to push bigger gears and risk knee damage due to higher knee joint loadings. [3] [4]

This is different from the design of other oval style chainrings, which have the smaller effective chainring diameter coincide with the cranks being at top and bottom dead centre (TDC and BDC), thus making the crank easier for the rider to turn through BDC for a constant chain tension. By having the chainring at its peak effective diameter with the cranks level, where the rider has maximum leverage over the crank during the power stroke, these designs are supposed to make better use of the rider's power output. [3]

Some cyclists find the benefits of Biopace worthwhile, including well-respected bike mechanic Sheldon Brown. [3] Some riders may also value a Biopace crankset for its historical accuracy on a vintage bike, for its novelty value, or even retro-cachet.

Sheldon Brown (bicycle mechanic) American cyclist, writer and mechanic

Sheldon Brown was an American bicycle mechanic, technical expert and author. He contributed to print and online sources related to bicycling and bicycle mechanics, in particular the web site Sheldon Brown's Bicycle Technical Info. His knowledge of bicycles was described as "encyclopaedic" by The Times of London.

See also

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References

  1. ↑ Berto, Frank J.; Ron Shepherd; et al. (2005) [2000]. The Dancing Chain: History and Development of the Derailleur Bicycle (2nd ? ed.). San Francisco, CA, USA: Van der Plas Publications/Cycle Publications. p. 297. ISBN   1-892495-41-4.
  2. ↑ Berto, Frank J. (2016) [2000]. The Dancing Chain: History and Development of the Derailleur Bicycle (5th ed.). Cycle Publishing/Van der Plas Publications. ISBN   978-1-892495-77-8 . Retrieved May 30, 2017.
  3. 1 2 3 4 "Sheldon Brown: Biopace" . Retrieved 2011-08-10.
  4. ↑ "Rotor Bike Components: QRINGS GENERAL INFORMATION" (PDF). Archived from the original (PDF) on 2011-09-02. Retrieved 2011-08-10.
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