# Chain binding on front derailleur



## ragweed (Jan 2, 2009)

Stetup: Chorus 10 gruppo. Chain is 8 months old with about 3500 miles and I clean it every two weeks. The rest of the drive train is original hardware and has about 7000 miles on it and doesn't show any abnormal wear (at least to my uncalibrated eyes.)

Problem: Chain is jamming when shifting the front derailleur from the small chain ring (39) to the large (53) one. The jam point is between the inside derailleur plate and the side of the big chainring. Basically as the chain begins to lift up it gets bound between the top of the FD plate where it curves out and the chainring. This happens about every 3rd for 4th shift.

So far the only adjustment I've made to try and fix the problem is lowering the FD a tad so that there's definitely a gap of only 1mm between the bottom of the FD and the top of the large chainring but doing so didn't make a difference. The alignment of the derailleur side plates look to be parallel to the chain.

Any ideas on what else I can look at to try and fix this?

TIA


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## chas0039 (Jun 26, 2007)

The only thing I can say is that 3500 miles is quite a bit over what most people here think is good. I would start with a new chain and see what happens from there.

However, I have not read anyone reporting this problem from a worn chain; possibly because they change them out earlier.


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## ragweed (Jan 2, 2009)

I ruled out chain wear just based on measuring it for elongation using a Park CC-2 chain checker. With it the chain measures 0.5 and given the CC-2 over-estimates chain elongation I concluded the chain is OK.

Later today I plan to raise up the FD to see what effect that has.


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## ragweed (Jan 2, 2009)

Raising the FD to an honest 2mm dramatically improved things. The chain did jam once but only after several minutes of going back and forth between the rings. I probably still need to nudge it up a tad but that can wait until later.


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## chas0039 (Jun 26, 2007)

Just so you know, chain stretch is not the only measure of chain wear. Campy chains are know to have very little stretch, but they still wear out. Glad your problem is improving.


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## strathconaman (Jul 3, 2003)

My experience is the campy front shifts best when the outer plate is parallel to the chain rings.


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