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hey everyone:

I have a 2002 Campy Centaur front clamp-on derailleur (double), coupled with a record 175mm double crankset of the same era. Campy Cantaur ergo shifters. They're on my back-up bike, which I haven't really ridden much for a number of years.

Anyway, took the bike out last weekend, only to discover that the front der won't shift the chain from small to large chain ring. Works fine on the small ring; if I manually get the chain on the big ring, the der just brings it down to the smaller one. Rear der working great. I adjust the outer and inner adjust screws of front der, and follow Campy's instructions for adjusting the der, with no success. I don't have any more thoughts on how to trouble-shoot...

Any suggestions for an obviously novice wrencher on how to get this thing going again?:mad2:

thanks!
 

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Sounds like the cable needs tensioning.

The high/low limit screws merely keep the der cage from going too far one way or the other. So long as the cage can move far enough to push the chain onto the large ring, without pushing it too far, the adjustment screw is fine. Likewise, the other screw is adjusted to keep the der cage from moving so far to drop the chain off the smaller ring. Once set, these usually don't need adjustment unless the position of the derailleur itself is changed, a new crankset is installed, etc.

FD action adjustment is made by increasing, decreasing the tension on the cable. Most FD don't have a barrel adjuster (like the one on the rear der), so it's a matter of loosening the clamping bolt and pulling on the cable by hand to take out all the slack.

There are inline cable adjusters that can be added, to make FD adjustments on the fly a lot easier.

P.S. There are a lot of good, illustrated bike repair tutorials on the Park Tool website. Check it out if the above doesn't make sense.
 

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Barrel adjusters

StephenH said:
the front der won't shift the chain from small to large chain ring. Works fine on the small ring; if I manually get the chain on the big ring, the der just brings it down to the smaller one.
Your bike probably has barrel adjusters where the cable casings coming from the handlebars connect at the upper end of the down tube. By visually following the cable, you can tell which one operates the front derailleur. Turn that barrel adjuster "out" (counter clockwise, like you were unscrewing it) a half turn and see if that improves the situation. It might not be enough, but things should look like they are closer to working. Continue to turn it out until you can shift to the big ring.

Chances are when you have shifted the front deerailleur shifter all the way "down" you will see that the cable is slack where it runs along the down tube. Another way to adjust it is to just turn the barrel adjuster until it removes that slack. If the barrel adjuster is all the way out and you still have slack, then turn it all the way in, loosen the cable clamp (5 mm allen bolt), pull the cable tight with your hand, tighten the bolt, and start over with the barrel adjuster.
 
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