Welcome to our Ask a Mechanic column where our expert mechanic Daniel Slusser answers your bike maintenance questions. If you have a question for Daniel, please post it on our Facebook Wall or e-mail Daniel directly at email@example.com. In this installment Daniel answers more bottom bracket adaptor questions and explains how to glue road tubulars.
I discovered your blog concerning those different BB standards and those adaptors. Great job, thank you! I was wondering if I could use an older style ISIS BB with this Sram PF30 adaptor? What do you think? Should be possible in my eyes….. From: Thorsten
It looks like bottom brackets are evolving faster than you can adapt. That PF30 adaptor will not work for you unfortunately, as it works only with outboard bearing cranks which are one generation past ISIS. So in loose Darwinian terms, your ISIS bottom bracket is a dinosaur. The SRAM PF30 to BSA adaptor requires that the crank utilize some way to have both arms press on the cups in order to keep the press fit adaptor inside the frame. With the ISIS bottom bracket the non-drive side cup is not fixed to the bottom bracket cartridge and the non-drive crank arm does not rest against the outer flange of the ISIS bottom bracket, even if the ISIS bb of your choice even has a flange on the non-drive cup (many do not). What would likely happen if you tried this setup is that the drive side cup would slowly walk outboard until the left crank arm bottomed out on the non-drive cup or adaptor flange and created a lot of drag and an unacceptable chain line. Sorry for the bad news, but it looks like it might be time to upgrade to a BB30 crank for that new frame you are eying. But just think about how much lighter a BB30 crank and bottom bracket will be! You could probably shave nearly half a pound off of your bike!
The process is essentially the same between the two types of tires. Road tires however are much more difficult to roll off of a rim with their lower profile and higher pressures. Because of this, you can eliminate one coat of glue for both the tire and rim that will make installation and replacement of the tire a bit easier. But, if you are a heavy rider (over 190lbs) or of a nervous disposition, go all the way and use the ‘cross tubular gluing procedure and rest assured that your tires will be a bear to remove.
Daniel Slusser is a professional bicycle mechanic with over ten years of experience. He holds a bachelor’s degree in business administration from HSU and a master’s degree in history from Cal Poly University. When he is not riding, wrenching, or writing he enjoys spending time with his wife and two children.