Retro-Direct

Retro-Direct

Retro-Direct is a gearing mechanism that was included on some bicycles built in the early 20th century. Retro-Direct allows a different gearing when the cyclist pedals backwards. Some bicycle hobbyists have built Retro-Direct onto modern bicycles.

The first version of Retro-Direct used two separate chains, however a single chain version soon followed. The single chain system is actually quite simple: The chain goes from the top of the pedal sprocket to the top of the rear wheel sprocket as usual. However, the chain then wraps around the wheel sprocket to an idler sprocket located between the wheel and the pedal, and then back to a secondary sprocket on the rear wheel, and finally back to the bottom of the pedal sprocket. Since the chain wraps around the secondary wheel sprocket in the opposite direction as the primary wheel sprocket, the cyclist only needs to pedal backwards to engage it. Usually the secondary sprocket is larger, which provides the cyclist a lower gear for climbing steep inclines simply by pedaling backwards. The two rear-wheel sprockets have separate freewheels, which the chain turns in opposite directions. Whichever is turned forward is engaged, while the other spins freely backward.

For clarity the drawing shows a system where the primary wheel sprocket is larger and gives a lower gear than the secondary wheel sprocket; pedalling forwards uses the lower gear ratio.

For the more common system where pedalling backwards uses the lower gear ratio, the drawing should show the chain from the small wheel sprocket going to the top of the chainring (pedal sprocket), continuing around the chainring, and ending up on the top of the large wheel sprocket. So to climb a hill, you pedal backward, and to go fast you pedal forward.

External links

* [http://members.westnet.com.au/rjharrop/recumbents/retro-direct/Retro-Direct2.htm Retro-Direct gearing]
* [http://myspace.voo.be/pcoupard/retrodirect_drive/ Pierre's Retro-Direct bicycle]
* [http://www.cykelhistoriska.se/hirondelle.htm Hirondelle Rètro-Direct]
* [http://www.m-gineering.nl/retrog.htm Hirondelle Retrodirect]
* [http://sports.groups.yahoo.com/group/retro-direct/ Yahoo! Group for retro-direct]
* [http://velospace.org/node/8517]


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • Retro Television Network — Type Broadcast television network Branding …   Wikipedia

  • Retro Hit Radio — Infobox Radio station name = Retro Hit Radio airdate = February 6, 2004 format = Retro, Old School eirp = 500 mW owner = private webcast = [http://www.retrohitradio.co.nz retrohitradio.co.nz] website = [http://www.retrohitradio.co.nz… …   Wikipedia

  • Retro Puppet Master — Infobox Film name = Retro Puppet Master caption = DVD cover director = David Decoteau producer = Charles Band Kirk Edward Hansen Vlad Paunescu Dana Scanlan Mona C. Vasiloiu writer = Charles Band Benjamin Carr David Schmoeller starring = Greg… …   Wikipedia

  • Retrograde and direct motion — Direct motion is the motion of a planetary body in a direction similar to that of other bodies within its system, and is sometimes called prograde motion. Retrograde motion is motion in the opposite direction. In the case of celestial bodies,… …   Wikipedia

  • Modulating retro-reflector — A modulating retro reflector (MRR) system combines an optical retro reflector and an optical modulator to allow optical communications[1] and sometimes other functions such as programmable signage.[2] Free space optical communication technology… …   Wikipedia

  • TÉLÉTOON Rétro — Création 4 septembre 2008 Propriétaire Astral Media (60 %) Corus Entertainment (40 %) Langue Français Pays d origine …   Wikipédia en Français

  • Teletoon Retro —  Ne pas confondre avec la chaîne québécoise Télétoon Rétro. Pour les articles homonymes, voir Télétoon …   Wikipédia en Français

  • Mode Retro —    The Mode Rétro is a name given to a trend in films made in the late 1960s and early 1970s on the subject of the Nazi Occupation of France in World War II. The mode was a tendency to deal openly with the issue of the Occupation and with French… …   Guide to cinema

  • Mode Retro —    The Mode Rétro is a name given to a trend in films made in the late 1960s and early 1970s on the subject of the Nazi Occupation of France in World War II. The mode was a tendency to deal openly with the issue of the Occupation and with French… …   Historical Dictionary of French Cinema

  • Pile a combustible a methanol direct — Pile à combustible à méthanol direct Les piles à combustible à méthanol direct ou DMFC (d après l acronyme de l appellation anglaise direct methanol fuel cell) sont une sous catégorie de piles à combustible à membrane d échange de protons dans… …   Wikipédia en Français

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”