Bicycle Mechanics - crank fit question
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.
09-26-08, 12:14 PM
I'm going to replace the 48-38-28 crank on my Specialized hybrid bike w/ a 42-32-22 mountain crank which takes a 113m Bb. the crank that is currently on my hybrid takes a 125mm Bb. Will going from the 125 Bb to the 113 Bb affect anything? Will it fit my frame ok?
09-26-08, 12:31 PM
It's good that you're replacing your BB - lots of people aren't aware that square-taper cranks need to be matched to specific spindle-length BB's in order to get proper chainline.
As to your question, there should be no problems putting a 113mm BB on the bike, provided you get the proper type. I assume - since you have a hybrid bike - that it's an english-threaded 68mm shell (by FAR the most common).
The only issue I can think of: chainline. I assume that the MTB crank was designed to work with a mountain bike's 135mm-spaced rear wheel. If your hybrid has 135mm-spacing, then use a 113mm bottom bracket. If the hybrid has 130mm rear-wheel spacing, then you'd want a bottom bracket with a shorter spindle.
But I'm pretty sure most hybrids have 135mm-spaced rear wheels so you should be okay.
09-26-08, 01:12 PM
my hybrid is a 7 spd and has a 132mm spacing, so would the 113mm Bb work?
09-26-08, 02:07 PM
the difference between the spacings (a whopping 3 mm) shouldn't cause you any significant issues. at worst, you'll need to re-adjust your derailleurs (which you'd already be doing after changing the crank.) if it *does* pose an issue later, you could try searching for half-size spindle lengths.
Powered by vBulletin® Version 4.1.12 Copyright © 2013 vBulletin Solutions, Inc. All rights reserved.