Bicycle Mechanics - School me on external BB's

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 : School me on external BB's

ricohman
08-18-08, 09:43 AM
I have an 08' Rocky Mountain Sherpa 30.
I want to swap the crappy FSA crank out for something with more gearing and less flex.
My crank is the older style internal bearing BB.
I see all new ones are external. Can these fit on my frame?
Or does the frame need to be made specific for an external bearing crank?

Sturmcrow
08-18-08, 10:42 AM
It should fit your bottom bracket just fine. The industry folks were smart enough to make them work with the vast majority of bikes already out there (cough, cough, integrated headset, cough).
ricohman
08-18-08, 11:08 AM
Good to know.
Now that I have read a bit more I may need to have the BB "faced".
I am assuming this is some type of machine work.

onbike 1939
08-18-08, 11:26 AM
Good to know.
Now that I have read a bit more I may need to have the BB "faced".
I am assuming this is some type of machine work.

I'm not sure why you should think this. The BB shell would be faced when the bike had the present BB fitted so unless you are aware of some damage to this then it shouldn't be needed.
ricohman
08-18-08, 12:01 PM
I'm not sure why you should think this. The BB shell would be faced when the bike had the present BB fitted so unless you are aware of some damage to this then it shouldn't be needed.

My bike has an internal BB. And I though that most bikes with internal BB's didn't have the facing done. I read this on the forum but obviously it could be wrong.
Thats why I am assuming I need the facing, but maybe I don't.
Sturmcrow
08-18-08, 12:06 PM
It's not as critical on a cartridge bottom bracket since the bearings are aligned by the internal sleeve instead of the BB shell. The facing tool is very expensive. Facing is one of those things best left to the LBS, and it won't be very costly for them to do it.

If the face of your BB is still painted, it probably wasn't faced previously.