Chain rub with Shimano compact crank/9-speed drivetrain?

[wwtsui]

Just switched from a triple to a compact (Shimano) crank, but kept the rest of the 9-speed drivetrain. My question: should all the gears be usable? Specifically, I can use all 9 cogs in the big ring, but not the 3 smallest cogs (12-14T) in the small ring -- I get chain rub against the front derailleur (9-speed Dura Ace). Is this normal, or do I just need to go back and have them adjust it better? The only other thing I can think of is that the LBS recommended a 9-speed SRAM chain over a Shimano chain -- any chance the SRAM chain is just a tiny bit wider?

Thanks for any insight/suggestions.

[Smiley]

No my wife has the same deal , I think a IRD compact front derailure could help out. Its not worth the change out for my wife's commuter so I leave well enough alone

[rustychisel]

Hi,

new member here, but understand your issues.

Having much the same setup as you, it's very common to find the small to smallest two cogs will give unreasonable rub - the result of a very small chainring (say 34) and chainline, and the setup of the front derailleur.

By finessing the front der. cage (angled very slightly outward at the rear) you should be able to clean it up a bit, but one of the tradeoffs with compact cranksets is needing to do more front changing than with a 53~39 (caveat: depending on your cadence and strength). By the time I'm getting down the cassette to the 14 or 13 (34x14 or 34x13) I'm ready to shift up to the big chainring (50x16). Properly set up it isn't such a messy double shift.

FWIW, I never use big x big either, in my case 50x23 due to a fairly severe chainline. I'm guessing you're using a 34T inner chainring, if - for the sake of experimentation - you changed that to a 36T you'd probably find the rub (on the inside of the 50T I surmise) much decreased.