At 11:03 PM -0600 7/13/09, John Wood wrote:
>Hi CR folks,
>I'm trying to set up a cyclo based 3 speed drive train on a 1950's French
>bike. At the time I got the frame, I also got what was purported to be the
>R. derailleur, shifter and crank/bb from said frame. A standard 5 speed
>chain will not fit the chainring, which seems 1/8" compatiable. 5 speed
>chain seems to fit the 3 speed cyclo freewheel fine. Is it most likely that
>the crank is incorrect, or did old cyclo 3 speed drivetrains in fact us 1/8"
>chains? Thanks much for the assistance.
The old Cyclo 3-speeds probably were intended for 1/8" chains. Even the 4-speeds fitted them at first.
This 1934 Reyhand is equipped with a 4-speed derailleur and 1/8" chain
http://www.vintagebicyclepress.com/
The 5-speed chains were narrower, and became popular in the late 1930s.
I am not very familiar with 3-speed Cyclos, as they mostly were found on lower-end bikes, but it is possible that the pulleys were switched for all Cyclos when the 5-speed was introduced... Does yours have an aluminum arm, a chrome-plated steel one that looks forged, or a pressed-steel one that usually is black? The former were the most expensive, the latter the cheapest.
If a 1/8" chain fits, I'd run that.
Jan Heine
Editor
Bicycle Quarterly
140 Lakeside Ave #C
Seattle WA 98122
http://www.vintagebicyclepress.com