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Old 01-21-07, 11:00 AM   #1
giaspec
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2007 chorus QS front derailleur compatibility with cervelos

I recently installed the new (and complete) 2007 Chorus grouppo on my 2005 cevelo soloist.

The problem that I have, is making the braze-on front derailleur to shift down to the small chainring

There are two main issues, and the second is a result of the first in this case:

First, the chain rubs on the inner side of the cage when it’s positioned on the lowest gear (largest cog). Loosening the adjusting screw doesn’t change anything… it keeps rubbing.

The chain shifts to the large chain ring without problem. The second problem occurs when I try to shift down again to the small chain ring; which doesn’t happen.

I've tried the following without succes:

-adjusting the derailleur as close as possible to the teeth on the large chain ring.
-loosing the cable tension to ease the travel from the large to the small chain ring.
-loosing the "lower limit" adjusting screw.
-the cage is as parallel to the chain rigs as possible.

I'm thinking that maybe with the UT cranks, the chain rings are closer to the BB; so close that the derailleur doesn't have enough travel to go down to the smaller chain ring. Therefore, it gets stuck on the large chain ring when shifting to the smaller.

Another difficulty with this bike is that with the internal cable system, I have no means to fine tune the cable tension once everything is set up.

Here are some pics and videos depicting the problem.

video 1: http://video.google.ca/videoplay?doc...77787&hl=en-CA

video 2: http://video.google.ca/videoplay?doc...99331&hl=en-CA

Any ideas??
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Old 01-21-07, 12:01 PM   #2
HillRider 
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Quote:
Originally Posted by giaspec
I'm thinking that maybe with the UT cranks, the chain rings are closer to the BB; so close that the derailleur doesn't have enough travel to go down to the smaller chain ring. Therefore, it gets stuck on the large chain ring when shifting to the smaller.
Look closely when the front derailleur is as close to the frame as possible. Perhaps it hits the seat tube before it can move in far enough. This is sometimes a problem with a triple but I've never seen it with a double.

Quote:
Another difficulty with this bike is that with the internal cable system, I have no means to fine tune the cable tension once everything is set up.

Any ideas??
You could fit in-line cable adjusters to allow tuning the tension.
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Old 01-22-07, 09:18 AM   #3
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Sorry I do not have a 2007 Campy Grouppo.
The spec in the case of a 2006 Record Compact for the spacing between the teeth of the large ring and the FD cage is 1-2 mm. I find that the shift from the big ring to the small ring is done best if the spacing is set up to no closer than the 2mm spec.
I find that if spacing is closer to 1mm or less it will shift but there will have to be next to no tension in the chain which I can set up by shifting to a smaller cog on the rear simultaneously. Try not to get caught mashing up an incline in the big ring and trying to go from the big ring to the small ring, it will not happen with the 1mm spacing for me, just makes a lot of noise and a lot of 'trim it' remarks from my biking buddies.
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Old 01-22-07, 06:56 PM   #4
giaspec
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so if you adjust spacing at more than 2mm, does it shifts better than less than 1mm?
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