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ASK RBA: ASK RC: REVIVING A SHIMANO FF SYSTEM DRIVETRAIN
Richard Cunningham
November 30, 2009
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I picked up a used Nishiki Olympic 12-inch 10 speed. It has a Shimano FF System. I had to make some adjustments to the rear derailleur to get it to line up with the small cog. I noticed when I cranked the pedals by hand and then stopped the rotation, the chain would also stop moving. With the FF system, shouldn't the gears be able to be shifted without pedaling as long as the bike is rolling? All the rear gears will spin without the pedals rotating, except the one the chain is on. I'm not sure if the problem is in the FF system or the cogs on the derailleur. What are your thoughts?
Thank You,
–Mike
The Shimano FF System was an inexpensive drivetrain using a front freewheeling crankset in the late seventies. The premise was that the drivetrain would always be in motion, so as long as the bike was moving its rider could shift the derailleurs. It worked quite well. The key ingredient was a freewheel that used a friction clutch so that it never coasted until a person’s leg got stuck in the mechanism—a sort of safety device that prevented injury to the fragile rear derailleur and the human race.
As for your problem, something is amiss with your cogset. There is a friction clutch built into the cogset (it’s on the back, near the spokes) that allows it to freewheel if you get your hand stuck in the gears. My guess is that the clutch is malfunctioning or the cogs are stripped on the freewheel body. Consult www.sheldonbrown.com for a good look at the FF system.
Contact Richard Cunningham for questions or comments, or just to talk bikes at: askRC@roadbikeaction.com
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