Bicycle Mechanics - Chain derails going from small to big ring

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johnaw24
03-23-09, 03:13 PM
Hi all,

I have a Surly Pacer with the following drive train components:

Shimano 105 10 speed STI shifters
Shimano Ultegra front and rear 10 speed dérailleurs
Shimano Ultegra 9 speed crank set
Stronglight 9/10 speed compatible chain rings
shimano 10 speed chain
Shimano Ultegra 10 speed cassette

All components are new except for the shifters which I got used.
The cables and housing are brand new.

Here is my issue:
When the bike is in my repair stand it shifts perfectly, but when I use the bike in the trainer or on the road I always have an issue with shifting from little to big ring, sometimes it derails, sometimes it shifts but takes a couple of rotations of the crank to complete the shift. I have the limit screw set so it can't fall to the outside, so it falls off to the inside. I originally had a 9 speed 105 front dérailleur but just changed that to an Ultegra 10 speed front dérailleur in hopes that was the issue, but I still had trouble shifting on my ride this past weekend. I followed the park tool website step by step. Any ideas would be greatly appreciated. Thank you in advance.


Panthers007
03-23-09, 03:24 PM
Sometimes a visual depiction is better then a written one:

http://bicycletutor.com/adjust-front-derailer/

Al1943
03-23-09, 03:41 PM
Have you tried adding tension to the cable?
Was the shifter in its lowest position when the cable was attached?
Is the derailleur low enough? Or too low? (unlikely)


Squeazel
03-23-09, 04:01 PM
I had a very similar problem with a Specialized triple crank- when I tried to shift into the middle gear from the granny, it often would skate over the teeth of the middle gear, then drop right off to the inside. A "dog fang" did no good, neither did any adjustment I could do. I changed to some nice Ultegra chainrings, and the problem went away completely. I suggest you might try a new quality matched set of pinned and ramped chainrings. Maybe a buddy has a set you can borrow to test.

Al1943
03-23-09, 05:55 PM
Squeazel makes a good point. Ramped and pinned Shimano (or similar) chainrings would probably shift better.