Front Derailluer shift isue

[capner2112]

I recently picked up an old Fuji road bike that I'm fixing up for a non-profit group. The components are all in good shape except for trouble shifting on the front derailleur.

The FD is a SunTour Compe-V running 2s and the chain gets caught between the high gear and derailleur arm causing it to seize forward pedaling. I've run it a few times in a trainer and 3 out of 10 times it shifted correctly. As far as I can tell it's in a good position. Any suggestions?

[DaveM]

Check height (should be only 2-3 mm above the outer chainring) and that it is parallel to the chainrings.

Also try to tell if the derailleur cage has been bent out of shape. That could have happened if it jammed under force. If so, that could be making it jam easier. Try to bend back into shape or you may have to replace.

[capner2112]

(09-07-2011, 06:15 PM)DaveM Wrote:  Check height (should be only 2-3 mm above the outer chainring) and that it is parallel to the chainrings.

Also try to tell if the derailleur cage has been bent out of shape. That could have happened if it jammed under force. If so, that could be making it jam easier. Try to bend back into shape or you may have to replace.

After looking over the positioning, I discovered the problem. There is a groove worn into the cage as if the chain were rubbing against it constantly on the inner chainring. There's enough of a lip that it prevents the chain from rising to the outer thus locking it. Best to just replace it then.

[Painkiller]

what size clamp do you need? might have one around I will give ya

[capner2112]

(09-08-2011, 07:58 PM)painkiller Wrote:  what size clamp do you need? might have one around I will give ya

Thanks for the offer. I'm going to try and file the cage to a smooth and level surface. I have a replacement derailleur set if that doesn't work.