Mountain Biking Maintenance and Repair : External Ball Bearing & Mountain Biking Tips
Mountain Biking Maintenance and Repair : External Ball Bearing & Mountain Biking Tips


So when we are working with our external bottom
bracket systems and our two-piece cranks and all that, we need to remember that there are
differences between different manufacturer’s methods of bearing pre-load and crank arm
attention. As you can see here, we worked on the Race Face setup, which is all based
on this one bolt here; it’s a self-extracting bolt. The self-extractor is actually a 10
millimeter bolt, and the pulling, the actual bolt that holds everything on, the pre-load
bolt, is an 8. So if I wanted to tighten that self-extractor back up, which I should because
I have some threads starting to show, I’d find a 10 millimeter Allen wrench, which I
didn’t bring with me today, and I’d tighten everything back up to the torque specifications
that they have on there. With the Shimano setup, I would just – this is like a plastic
little pre-load bolt. It’s like a six-sided, kind of starfish-looking thing. And I’d just
tighten that up very lightly, like 15 foot-pounds. And then I would slide my non-drive-side crank
arm onto my spindle, which is attached to my drive-side arm, and I would do up a bolt
here and a bolt here that would clamp down on the spindle, to about 15 foot-pounds. I
believe that is the torque specifications. It’s on the crank arm when you get it, so
take a look at it, and if you don’t understand what those torque specifications mean, you
can always bring it to a bike shop. Just keep in mind that different crank manufacturers
have different ways of retaining the cranks. One thing that is consistent across all of
them, however, is the size of the spindle. So the spindle and then the bearings are interchangeable.
So if you find that one type of manufacturer’s bearings work better for your application
and your climate than another, feel free to keep using those bearings when you change
or upgrade your cranks.

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