New build: Chain rubs seatstay in smallest cog

[ldamelio]

As above - building up frame (Sachs cross). Drivetrain is Campy record 10 QS FD, Chorus 10 medium cage RD, record 10 chain. Wheels tried are Campy Vento w/13-29 Centaur cassette and Record/CXP 33 with 13-26 Chorus cassette. Both wheels true and dished correctly. They sit perfectly centered in this frame and work well in other frames. Chair rubs hard against the seatstay just above the dropout - gets stuck, not just a slight rub when in the 13. Futzed with derailleur limit screws to no avail. Another set of wheels with a 12 tooh small cog (Wheels MFG Campy conversion cassette - Ultegra w/Campy spacing) just barely works. Would really like to use my 13/26 and 13/29 cassettes. Any insights into the problem? Just the pecularities of the frame/dropouts ? Chainline problem ? I guess spacers would work as a last resort or I could give in and buy new cassettes, but I'm wondering if there's anything I missed or a more elegant solution. TIA for replies

[DartanianX]

I had this problem when I was running junior gearing on my TT bike. From how I understood what your issue is the 13 is just to big to have as the last cog. Just guessing from what I've read.

edit; If there is a spacer between largest cog and wheel take it off and put a spacer on the other side of the wheel, between the 13 and lock ring. This might give you just enough room. Thats all you can really do. That or buy a new cassette!

[timzcat]

This may sound crazy but check the rear derailer hanger, particularly for twist.
Don't know what the hanger and dropout design but most of the time the wheel is clamped against the hanger and if it's bent it will throw off how the wheel sits in relation to the hanger/seatstay/chainstay.

I have seen a bent hanger cause a chain to rub the seat and chainstay when in the 11 tooth. And at first look you wonder how it's possible the wheel and cassette are standard stuff.

[Zigmeister]

Cassette could also just be too far out due to the hub spacing/width, or spacer on the inside pushing the cassette too close to the stay even when torqued to spec.

I have this problem with my zipp 303s almost. I have to put a spacer on the inside of the cassette to keep the RD from hitting the spokes under load when in the biggest gear. But that also puts the chain real close to the staay, but I rarely go into that anyway so it isnt a proble. Since zipp is using a wider hub, it makes sense your cassette wil be moved outward if there is no tolerance on the axel width, if that makes sense.

Dont know how an 11 speed wouldnt have these issues on many frames due to the 130mm width standard and tolerances.

[ldamelio]

Heard from the man himself, Richard Sachs, who was kind enough to answer me on another forum. Frame was designed purpose built for cross racing so no room for weenie 13 small cog. Will man up and put on the intended 11 or 12 low. Fixes suggested (spacers, etc.) might work, but not the right thing atmo given the definitive word.

[bm0p700f]

I have this problem with my Traitor frame. Solution a cassette with a 11T cog. I never use it but what the heck it will never wear.

[dj97223]

I don't know cross, but why would a frame be designed so one cannot use a 12 or 13 cog?