# Big ring trim and chain rub



## Metaluna (Aug 26, 2005)

With the newer shifters (Force 2010 in my case) having trim only on the large ring, has anyone here experienced uncorrectable chain rub in the small/small combo on a compact crank? (Smallest 2 cogs actually) I can live with not using these gears, but I'm wondering if this is normal behavior or if I should keep looking for solutions. I think I've ruled out all the usual things - cable tension, limit screws, cage rotation and height, bent chainrings, etc.. I posted a more detailed description of my problem over at Bike Forums,

For one thing, does anyone know if a 2010 Force FD might be better matched to the trim capabilities of the newer shifters? I'm currently using a Rival FD. Just for yuks, I also tried an Ultegra 6600 FD and it was even less tolerant of cross-chaining. The one thing in common with these two FDs is that they were both designed with shifters with small ring trim in mind.


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## sixate (Jul 6, 2009)

Trim has nothing to do with the derailleurs. That's controlled by the shifters so I don't see how a 2010 Force FD would be a better match.

Chain rub in small/small is gonna happen, but you shouldn't really be using that combo much, or at all.


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## asad137 (Jul 29, 2009)

I get rub on the two smallest cogs in when I'm in the small chainring too. Compact crank, bike with relatively short chainstays. I just don't use those gears (they're redundant with gears accessible while in the big chainring).

Asad


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## Metaluna (Aug 26, 2005)

sixate said:


> Trim has nothing to do with the derailleurs. That's controlled by the shifters so I don't see how a 2010 Force FD would be a better match.


Yeah, I figured it was a longshot. My thinking was that FD's can be shaped to reduce the amount of trimming needed, so maybe they changed the cage shape a bit. For example I've noticed that Campy FD's bulge out a bit at the outside rear of the cage, presumably to give more clearance for the chain when in the small ring and smaller cogs.



> Chain rub in small/small is gonna happen, but you shouldn't really be using that combo much, or at all.


I agree, it's not a big deal. Just wanted to make sure this was fairly normal, and not a symptom of a more general problem.


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