Octalink to Hollowtech II + BB30

[One-eyed Sailor]

I have an old Cannondale F29 mtb (bb30) that I'd like to upgrade the crankset from an Octalink to a Hollowtech II.
I searched Shimano's compatibility site and watched a couple of videos but am still unsure if it's possible.
Chainline corrected with the shims, right?

Any advice is greatly appreciated!

 

[ishaw]

I thought bb30 and ht2 were not compatible unless you use an adapter BB as the axle diameters are different.

 

[Black_puma]

I have an old Cannondale F29 mtb (bb30) that I'd like to upgrade the crankset from an Octalink to a Hollowtech II.
I searched Shimano's compatibility site and watched a couple of videos but am still unsure if it's possible.
Chainline corrected with the shims, right?

Any advice is greatly appreciated!

Octalink and Hollowtech II require different bottom brackets. Octalink bottom brackets are similar to regular bottom brackets but with an splined Spindle that fits Octalink cranks, the cups and bearings fit inside the shell of the bottom bracket. The spindle is usually a smaller diameter than that of a Hollowtech crankset. On the Hollowtech bearings are seated outside of the bottom bracket shell increasing the stiffness, allowing for lower weight cranks. And Hollowtech bottom brackets require spacers to allow for adjustment of chain line and different sizes of shells. Hope that helps, if If I am wrong please correct me, I am not perfect, always willing to learn!

 

[One-eyed Sailor]

Thanks for your input, it turns out that when shimmed correctly, the Hollowtech II BB and crank work perfectly on a BB30 shell.

 

[ishaw]

I'm confused. Having reread your post, you say the frame is bb30 but you want to upgrade from octalink to ht2.

The pics are of an octalink and ht2 cranks, and the final one with cranks mounted is an ht2.

I found this site which explains a lot of the differences between BB standards:

https://www.slowtwitch.com/Tech/Bottom_Bracket_Standards_2573.html
This thread suggests an adapter is needed to convert bb30 to ht2?

https://singletrackworld.com/forum/topic/gxp-crank-into-bb30-frame/
Did you need an adapter or did your ht2 BB screw straight in?

I have other 30mm axle cranks and bvs that screw into a standard frame BB shell, but I thought bb30 was press fit with the bearings within the BB shell. The overall width narrower, he certainly BB30.axles shorter than ht2

I have bb30 on a road Cannondale and that would need an adapter to run ht2 axle as narrower.

 

[One-eyed Sailor]

You know what? I think you're right and I'm.... embarrassed.



Nevermind lol

 

[ishaw]

Don't be. Every day is a school day. I've learned Cannondale pioneered the bb30 and research suggests that the f29 was a bb30 frame at some point in its past (2015 on a review I read).

So, is yours a bb30 with an adapter in the BB to allow standard threaded bbs? I'm curious.

 

[One-eyed Sailor]

Mine is a 2008 with a threaded BB shell, no adapter.
The lower BB in this photo was the one I just replaced. The black one is the one I just installed.