Bicycle Mechanics - MTB frame and road crank for 1x7?

Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.



PDA

View Full Version : MTB frame and road crank for 1x7?

jzsoup
06-20-09, 12:01 AM
Trying to use MTB frame and a Bontrager road crank with external bearings. I removed the large chain ring to make it a 1x7. Clearance is an issue as the ring rubs against the chain stay; even after I moved the ring to the outside where the large ring would ordinarily sit.

Any suggestions? Ebay it and start over with a mountain crank?

Garthr
06-20-09, 04:41 AM
Too bad it's an ext. bearing crank, because all you'd need is a longer BB. Yeah, sell it and get a Sugino double or triple.
http://www.velo-orange.com/suxddocr48.html
http://www.velo-orange.com/suoldlotr.html

The double or triple with a 113mm BB, using the 36 would likely work, but it depends on the clearance of your mtb frame. I'm not sure of the 34t of the double would clear. If it's really bowed you may need a 115. You can also use BB spacers in 1, 1.5 or 2mm of you need a bit of clearance on the drive side.

That's what makes tapered cranks so useful . . tweak-ability :)
AEO
06-20-09, 05:05 AM
34T inner/middle ring might be very tight clearance for a MTB frame with a road BB.
my CX bike has bowed chainstays like a MTB and it needs a 110mm axle for a triple, while a shimano 50/34T compact double external BB just barely cleared the chainstay.