Front Derailleur Question
 

Is there an inherent difference in where a FD will fall laterally with respect to the chainrings when you compare a clamp on FD and a braze on FD with clamp adapter?

I have a braze on 9 spd FD w/ clamp adapter (older Shimano 600) and a Ultegra double 10 speed crank. The crank, chainrings + chain are the only 10spd components, everything else is 9 spd. It works fine, except I really need the FD to move inward towards the bike another 1/8" or so to get it centered properly and noiseless. I've adjusted the limit screw to allow it to come in as close as possible. At this point, it's just the geometry of the 4 bar parallel linkage preventing it from moving closer.

Will a clamp on 9 spd derailleur have any effect? (get rid of braze on + clamp adapter)
Does the 9spd vs 10 spd make any difference? I wouldn't think so, but maybe I'm missing something...

thanks a ton!
bob

No.

Do you have any idea whether the front chainline is correct?

No I don't. I was just thinking of that this weekend. I'll measure it and report back...

Thanks
Bob

If the derailleur is moving in as far as possible, usually defined by striking the frame, and is still not doing the job, then it would seem that the only thing that fix the problem is a longer bottom bracket axle.

chainline
 

He is running a Ultegra 10spd crankset, the chainline is not subject to change. 43.5mm

http://techdocs.shimano.com/media/te...9830616000.pdf

I'm not sure if it applies to 9 or 10-speed fd's but for Shimano 8-speed components, the clamp-on fd sat slighty further "forward" than the braze-on + adapter. I had to use an 8-speed triple clamp-on on my '96 Litespeed so the dearilleurs actuating arm would clear the rear tire in the big chain ring. The braze-on + adapter set-up rubbed the tire.

The 9 and 10-speed fd's have been redesigned with a shorter actuating arm so this problem no longer exists.

if the FD is hitting the frame, try rotating it on the seat tube until it clears the chain. the FD cage should be parallel with the chainrings, but a lot of times, contact between the FD and the seat tube prevents the cage from clearing the chain. a tiny amount (a few degrees) of rotation will fix this and is acceptable.

When you have problems like this, you check everything. After all, it's a simple enough measurement.

Thanks everyone for the very thoughtful replies.
I finally was able to spare some time last night to measure the front chainline. Sure enough, it's right on the money. I measured 43.42mm. Not bad considering Shimano's target of 43.50mm.

The FD does not hit the frame. It simply does not have sufficient travel in the 4-bar linkage to move inward enough.

I'm not sure what else to check? Maybe I should swing by the LBS and try on a new clamp-on FD to check sizing? I'm sure I can score a clamp on 9 spd Ultegra FD cheap enough, but I'd like to know that I've exhausted all other possiblities before spending more $$$...

Thanks again-
Bob

next...
 

I would try new derailleur next. Maybe a 105 FD?
9 vs. 10 could make a difference!?