XTR M950 cranks on Ultegra BB-6500 bottom bracket?

[syncrosfan]

Has anybody here tried to run a XTR M950 or 952 crankset with an 109.5 Ultegra BB-6500 bottom bracket? XTR bottom brackets are fairly rare and if they do show up they're fairly expensive (or beat to hell). I am aware that XTR BB's came in the 112.5 and 116 mm spindle length as opposed to the 109.5 (or 118.5) on the Ultegra but I wonder if the chain-line would get that messed up by using a slightly shorter spindle. (we're talking 1.5 mm shorter per side). The interface is Octalink V1 in both cases so it should be interchangeable. Did anybody here tried this route? Ultegra bottom brackets are more easy to obtain at a decent price than XTR BB's.

 

[fjpshaw]

Re:

I have tried this, and from memory the tapered end on the NDS crank arm was pulled in to the bb shell slightly too far that it would have worn on the shell if it was turned. I run 952 cranks on a 952 bb, and that interface is pretty tight.

 

[kase1983]

Re:

ive used dura-ace BB on XtR cranks in the past.

 

[syncrosfan]

So you tried to adjust the chain-line on the drive side to 47.5 which in turn moved the NDS crank too far in?

 

[unkleGsif]

Re:

Currently running the dura ace v1 spline on the kilauea... no issues with what i think is a 109.5

 

[syncrosfan]

"ive used dura-ace BB on XtR cranks in the past"
I did stumble upon another forum where somebody stated that due to its construction the 109.5 Dura Ace and Ultegra BB's actually give you a wider chain-line than a 112.5 XTR BB so the chain line wouldn't be a problem... Seems counter-intuitive to me since the interface is the same Octalink V1 and spindle length is what it is (but I'm no expert in Shimano road BB's so maybe it's true?...)
"Currently running the dura ace v1 spline on the kilauea... no issues with what i think is a 109.5"
I think I'll give it a try. Worst case I sunk 30$ in the sand for a brand new Ultegra BB but if it works it might be a much cheaper alternative to a brand new XTR BB.

 

[bm0p700f]

I did try mounting an m950 bb on a 109.5 mm bb and the ds crank arm fouled the chain stay I think the 118 put the chain line well past 50 mm. The trek I have it on has a 50 mm chain line so that is an important factor. The only way I could mine to work on the trek is with a m950 bb

 

[syncrosfan]

The 118 would be waay too long. At this stage I'll just have to hope that the crank arms will clear the chain-stays. The cranks are going on a '97 Rocky Mountain Vertex LE. uncleGsif's frame is a steel one so all the tubes are rather slender, hope that the Vertex doesn't build too far out...

 

[fjpshaw]

Hi, sorry, I honestly can't remember if there was any messing around with chainlines (this was all a couple of years ago), but I don't think there was. Trying to think about it, the installation was on a Zaskar 73mm shell, so I wonder if perhaps I had picked up a 68mm BB by mistake and therefore the spindles would have been sat slightly further 'inside' the cups? Dunno...can't remember, but hope yours works out. Seems others have managed without bother.

 

[cce]

all road BBs are 68mm, so that might well have been your problem