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, or accelerating, 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. The drawing shown here is correct except the chain from the small wheel cog goes to the top of the chainring, continues around the chainring, ending up on the large wheel cog. So to climb a hill, you pedal backward, and to go fast you pedal forward.

External links

• Retro-Direct gearing
• Pierre's Retro-Direct bicycle
• Hirondelle Rètro-Direct
• Hirondelle Retrodirect
• Yahoo! Group for retro-direct

Bicycle parts | gears