Bicycle Mechanics - front derailleur band size

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coasting
03-27-08, 06:02 AM
The smallest band size on shimano 105 FD is 28.6mm. I thought this was the standard diameter but on my bike it is a bit too wide. My seat tube is reynolds 531 but seems to be a tiny bit under 28mm. This is smaller than standard isnt it?

I tightened the screw all the way and the clamp is completely shut but when I pull on the shifter over time the tension pulls the FD down about 1 mm during a ride. Any suggestions?

nitropowered
03-27-08, 06:26 AM
Use a soda or beer can and make a shim
Grand Bois
03-27-08, 09:06 AM
Is your bike French?

coasting
03-27-08, 11:16 AM
Is your bike French?

No it isn't. It's british I think.
Grand Bois
03-27-08, 11:28 AM
A British seat tube has got to be 28.6mm or 1 1/8 inch. A French frame would have a 28mm metric seat tube. If it's not French, I don't know what to tell you. The Campagnolo FD on my PX10 does the same thing, but I have an undersized tube to blame.
coasting
03-27-08, 11:48 AM
A British seat tube has got to be 28.6mm or 1 1/8 inch. A French frame would have a 28mm metric seat tube. If it's not French, I don't know what to tell you. The Campagnolo FD on my PX10 does the same thing, but I have an undersized tube to blame.

Thats what I thought! Very odd. Did you make a shim from a coke can? I checked with a couple of shops and they didn't sell any shims. A shim did come with the FD but just to get from 31 mm to 28.6