bifford

Hi,

I know this is a common question, but I've been unable to find a suitable thread.

PROBLEM: I am essentially unable to shift up to the big chainring while I'm riding, but the shifting is fine when it's on a stand. To be clear, I AM able to shift on the road, but it takes a lot of work and the front derailleur is quite fickle. There doesn't seem to be any real pattern: sometimes I have to shift 2-3 times (very hard) before it eventually engages, and every blue moon it shifts right away.

SETUP: 2004 Cannondale six13 with Campy Centaur build (FSA double crank, centaur derailleur and ergo shifters)

QUESTIONS:
1. Is it common for the front derailleur to work well in the bike stand, but NOT on the road.

2. Because the shifting is smooth while in a bike stand, shouldn't that imply the limit screws are properly adjusted?

3. I don't think my Centaur components have a barrel adjuster. What's the deal with that. How can you fine tune cable tension without a barrel adjuster? Have other people run into this problem.

4. My LBS said my front derailleur may be bent. But again, why would it shift fine in the stand then? If it's bent, shouldn't the shifting ALWAYS be difficult?
I have taken it to my LBS on multiple occasions, but I can't get the shifting to work like it should.

Thank you all very much.

Bifford

77Univega

--- I had a similar problem and discovered the nut holding the crank to the spindle was loose. So the chainring went out of alignment only during the stress of pedaling. Tightened the nut, all fixed.

fmw

First, release some tension on the limit screw for the large ring. If that solves it, then you're done. If not, change the angle of the front cage to the cassette. Just loosen the FD clamp and turn the FD so that the FD cage points to about the middle of the cassette and retighten and readjust the FD. Make sure the distance between the large ring teeth and the cage is about 1 - 3mm. That clearance can get out of whack when you turn the derailleur. It is common for bicycle assemblers to line up the cage with the large chainring and this isn't always the best way. It is often better to have it turned just a little clockwise on the seat tube.

If you don't have barrell adusters, then you need to adjust the FD cable at the FD itself. If you need to move the cage out a little so that it is more reliable shifting to the large ring, just pull it out manually and wedge something between it and the seat tube. Then you can loosen the cable clamp, pull the cable a hair tighter, retighten the clamp and test.

If none of these things fixes the problem, then I'd visit the bike mechanic. But I would bet it is just an issue of adjustment at one of these three places.

bifford

Thanks a lot fmw and 77Univega.

I'm definitely going to give your advice a shot.

bifford

Mentor58

and if you don't have a barrel adjuster, you can get one that splices inline with the cable. It's really tough trying to make fine adjustments by actually adjusting the cable at the clamp. Not saying that it CAN'T be done, just that it's a lot easier to fine tune with an adjuster.

Steve W.