Modern BB30 cranks on a retro frame? Yes you can! :)

Mikey08

Kona Fan
I got some secondhand Sram X01 cranks last summer and at the time I had no idea about all these modern BB standards. When they arrived my heart sank as the axle looked way to short. On closer inspection and measurement I thought I was out of luck. However...

BB30 is a narrower standard than the old BSA standard but there's a trick. BB30 cranks will have a preload adjuster on one side and a spacer on the other. Remove these and you have a long enough axle to fit through your frame and its external BB cups. My frame has a 68mm BB shell. I used a 'BSA30' type bottom bracket (Race Face Cinch). BSA refers tp the thread size and type and 30 refers to the spindle diameter ie; 30mm. The whole thing slots together nicely with no play or binding in the bearings. If your BB shell has been faced you may need to take out the slack with thin washers or even a 'wavy washer'. These are readily available.

Chain line. In order to get the right chain line for a 1 x single ring setup I had to use a 6mm offset chainring. This got me within a gnats ballbag of the center of the cassette and my shifting works fine with no skipping grinding or chain drops.

So there you go, it can be done!

In case anyone's interested.... :roll:

:LOL: :LOL:
 

TheAntsPants

Devout Dirtbag
Yep. Worth pointing out that you will need a dedicated BB wrench for BSA30. The wrench for standard outboard BBs will not work.
 
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