Octalink BB sizes

[kaiser]

Folks I've recently got a octalink chainset and wondered if anyone knew what size bb to use? Listed against the chainset (xt m751) are 2 sizes 113 and 118, is 2.5 mm each side gonna make that much difference? Running the bike as a single ring up front too.

Also are all octalink created equally?I would have thought the splines would be the same but is it possible that the road versions are different?


Cheers

 

[Xesh]

I'd use the shorter of the two sizes if you're going to run it with a single ring. In my experience you only need to use the longer size if you've got really wide chainstays and need the extra clearance.

AfaIk most octalink splines are the same except for the usual suspects (XTR and Dura-Ace). I have used a 105 BB in an MTB before without problems.

 

[kaiser]

Sounds good to me, cheers

 

[drystonepaul]

I tried a 105 octalink BB with some Deore cranks and the splines are much shorter so they rapidly worked loose. So I'd stick with the ES25, ES30 or ES51 to ensure compatibility with your XT cranks.
I've also got some XT M751 cranks which I'm running with a 113mm ES30 BB with triple rings, so that sounds about right for yours too IMO.