Thread BB + PF30 cranks

[mountain_goat]

Hi all, just needing some advice how to make the above two work?

Thanks

 

[Zaf]

Which cranks and which frame more specifically?
PF30 cranks usually preload the bearings with a wave washer or a tightening ring on the spindle. This can sometimes interfere with the real estate available for having enough length of spindle emerging from the non-drive side when matched with a BSA BB.

Anyway, specifics first, as not all 30mm spindle cranks are equal or require the same work around.

 

[mountain_goat]

Hey Zaf,

Frame - Yeti Bigtop
https://www.vitalmtb.com/product/guide/Frames,7/Yeti/Big-Top-29er,6830

Cranks - S-Works Carbon Mountain Crank Arms
https://www.specialized.com/au/en/s-works-carbon-mountain-crank-arms/p/116720?color=209374-116720

 

[Zaf]

And it's definitely the current model of the S-Works crank? ie, single spindle attached to the drive arm only, not the campy style "spindle on both sides that threads together in the middle" style crank?

 

[mountain_goat]

Single spindle attached to the drive arm only.

 

[Zaf]

So the biggest concern is that the PF30 spindle can be shorter, although most MTB standard PF30 shell widths line up to one of the 68/73mm standards.
In any case, you'll be chasing BSA style BB that accept a 30mm spindle, namely:
e*thirteen
Race Face (Cinch)
Hope BSA 30's
Wheels Manufacturing BSA30
etc. etc. etc.

The next trick is using the cup spacers (that sit between the frame and cup) to make sure your shell width matches nicely so that the PF30 crank is just pre-loading the bearings, and not tightening onto them or sloppy.
Also note that BSA 30mm spindle BB cups usually take a different tool, as they have to make the cup diameter a bit larger in order to accommodate the bearing sizes properly.

I'd be measuring the spindle length first and then double checking the shell etc.

 

[creaky]

This is too difficult. Just sell me the crank arms for $250 and buy some XTs ...