Originally Posted by
DannoXYZ
The problem is with the proper (shorter) BB-spindle for road-cranks along with the larger diameter of the road chainrings, this will cause the inner chainring to rub on the chainstays. Denting the chainstays is what is done on a lot of MTBs, even road-bikes. I've done this quite a few times, here's the procedure:
1. install proper-length BB
2. slip on right crankarm with chainrings (make sure chainrings are true)
3. mark on chainstay where the tips of the chainring-teeth end
4. remove crankarm and BB
5. heat spot on crankarm with oxy-acetylene torche until an area the size of a quarter glows deep cherry red
6. hold a flat metal bar over the glowing spot, line up the edge of the bar with the mark for the tip of the chainring-teeth
7. make sure metal-bar is parallel to the plane of the frame and chainrings (parallel)
8. tap the bar with hammer, depending upon thickness of chainstay and weight of hammer, tap harder
9. re-install BB and crankarm and inspect clearance. I prefer to have about 2mm. Repeat from step #5
Thanks, is getting the spot red hot better for the tubing? I was thinking of denting them but without the torch, and looking at the clearances a dent for the end of the cranks might also be needed. What I'd really like to do is actually bend both the chainstays inward in the middle of there length since there is a lot of extra space in there without the fat knobby tires. My main desire is to have a narrower space between my feet like on road bikes.