I am suffering through this right now. my setup is 2 chainrings and a capreo setup in back (9 speed with small 9-tooth cog). but the problems are not limited to chain rubbing - I can't get it to downshift onto the smallest cog b/c one of the jockey wheels catches on the dropout. well, there is a slight hack where I go to the smaller front chainring or hit a bump, but then I get the chain rubbing you describe.
It has become so annoying that I have considered going back to a stock config...but I would really, really miss the drop bars.
Originally Posted by
rickybails
I have a technical question. What have others done about the problem of the chain rubbing on the seatstays when in the smallest sprocket, and you're running a front deraileur and 2 chainrings?
I converted my swift from 520 back to 406 wheels (so I can race in the London Nocturne folding bike race this Saturday), and for the first time am running a front mech and 2 chainrings. Previously I've only ever run a single chainring and put it in the inner ring position where I can get the chain to clear the seatstays with other mods. But with an outer chainring, the chain rubs on the seatstays in top gear.
One way of giving the chain more space is to have a 130mm (road) rear hub instead of 135 (mtb, capreo), and put a ~2mm washer between the hub and the dropouts to push the seatstays out. But I'm doing that already and it's not enough.
By adjusting the left-right position of my BB, I have pushed the chainrings as far left/in as they can go without them rubbing on the chainstay, but still the big ring is too far right/out to stop the chain rubbing the seatstays. Ideally I would use my 57T chainring to get the top gear I need with the 11T small sprocket. I have been able to acheive the same top gear by running a 61T chainring with the 12T. The 61/49 chainrings have been no problem with shifting so far.
The only other think I can thing of is having a 130mm rear hub with 5mm spacers all on the drive side and increasing the dishing on the spokes to move the rim 2.5mm to the right so with the spacers it's back in the middle. Seems a bit extreme though.