Author Topic: XTR 9 speed triple on a 68mm road BB  (Read 1199 times)

Phil W

XTR 9 speed triple on a 68mm road BB
« on: 30 June, 2019, 11:42:52 pm »
I have a post PBP project where I will be building up a new recumbent bike from a frame set.  At the same time I have an old mountain bike that is just sitting in storage as the frame is dead.  The mtn bike has xtr 9 speed bling on it (bought ex demo) and I'd like to put the drivetrain on the new frame.    I believe the crankset is XTR M970 hollow tech II and sitting on a 73mm BB MTB.  Is it possible to fit this crankset on a road BB 68mm shell with some kind of spacers or is that fantasy? The outer ring is 44 teeth but I presume I can fit a 46 or even 48 ring for a bit more top end for the road?

Seems a shame to give this drivetrain away only to spend loads on a new drivetrain for the new project..

Re: XTR 9 speed triple on a 68mm road BB
« Reply #1 on: 30 June, 2019, 11:53:14 pm »
you only need 2.5mm of spacers each side, so why not?

cheers

Torslanda

  • Professional Gobshite
  • Just a tart for retro kit . . .
    • John's Bikes
Re: XTR 9 speed triple on a 68mm road BB
« Reply #2 on: 06 July, 2019, 11:07:07 pm »
It is vital that BB matches the crankset. And they're so inexpensive fit a new one!

Is that the chainset with the weird lefthand thread locking ring on the crank? or am I talking bollox again...?
VELOMANCER

Well that's the more blunt way of putting it but as usual he's dead right.

Re: XTR 9 speed triple on a 68mm road BB
« Reply #3 on: 06 July, 2019, 11:15:44 pm »
https://si.shimano.com/pdfs/ev/EV-FC-M970-2592.pdf

it seems to be mostly standard HT-II apart from the left crank attachment and the bearing preload setting/retention...?

cheers

Re: XTR 9 speed triple on a 68mm road BB
« Reply #4 on: 07 July, 2019, 09:27:29 am »
Reading forum posts the left crank seems to be a very tight interference fit to the spindle and the bearing preload is set by the funny clamp thing. Various special tools are involved.

Looks like an LBS asking you not to darken their door job.

Phil W

Re: XTR 9 speed triple on a 68mm road BB
« Reply #5 on: 20 July, 2019, 04:03:27 pm »
Reading forum posts the left crank seems to be a very tight interference fit to the spindle and the bearing preload is set by the funny clamp thing. Various special tools are involved.

Looks like an LBS asking you not to darken their door job.

Nah, fitted them on mtn bike just fine. I'll still have any necessary tools hanging about in my toolkit.