[Standards] MTB Drivetrain - Cranks and BB's

Education Resources
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In case anyone had missed this, these do exist now. I think SRAM really did their homework with these BBs and the sealing - despite the smaller OD bearing (smaller than the usual 6806 commonly found in BBs for 30mm spindles) the units last a very long time.
My colleague who used to go through several BBs / year has now been on the same one for over 2 years and he’s ridden in all sorts of weather and been on the road a lot with limited ability to service his bike. Very impressive.

Which leads me to a “hack” that many of you may find useful. Given the great sealing quality and relatively low cost of the SRAM T47 BBs, wouldn’t it be great to be able to use them with a 30mm spindle? Well, you can!

I just popped the little plastic reducer out of the bearing and ran a Dremel sanding drum a few laps around the ID of the reducer to remove the lip. Thus turning the reducer into just a regular BB spacer. Successfully installed with a set of cranks with a 30mm spindle.

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22

I’ll see what I can find. Stay tuned.

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23

Which press fit is most common on mtb? BB92 or PF30?

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I don’t know which one is more common. PF92 defo makes more sense for steel bikes. That’s what Chromag used to predominantly use, although they’re doing more and more bikes with BSA shells these days (which is a good move IMO).

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