Dura Ace and XTR

[bikemonk]

Does anyone know if the old Dura Ace 7703 bottom bracket is interchangeable with the XTR M-952 bottom bracket?

Thanks in advance

 

[alfeng]

Does anyone know if the old Dura Ace 7703 bottom bracket is interchangeable with the XTR M-952 bottom bracket?

YES, they are interchangeable!

I have mounted an XTR crankset on a 109.5mm DA BB ...

Similarly, I have mounted a DA crankset AND also an Ultegra 6503 crankset on a 112.5mm XTR BB (on a steel frame). In the latter instance, I wanted to see if I could avoid using the longer 118mm BB which is designed for triples [this allowed me to swap between a double & triple crankset without changing anything other than the front derailleur stops] ... and, everything shifted fine (with Campagnolo shifters & an Ultegra 6503 front derailleur) and I have found that that the longer/(118mm) spindle may only necessary on SOME (e.g., touring) aluminum frames which have 135mm rear spacing in order to get the 52t/53t chainring & crank arm to clear the chainstay.

AFAIK, the Octalink V2 (version 2) spline is exclusive to the XT & LX cranksets -- I wish Shimano had made an Octalink V2 BB with a shorter-than-113mm spindle.

 

[Peter@vecchios]

Does anyone know if the old Dura Ace 7703 bottom bracket is interchangeable with the XTR M-952 bottom bracket?

Thanks in advance

Depends on the frame. The splines of each are the 'V1' type, not the fatter ones of V2, but the left and right offset are different between 109/118 road BBs and the what the XTR MTB crank requires.

 

[alfeng]

Depends on the frame. The splines of each are the 'V1' type, not the fatter ones of V2, but the left and right offset are different between 109/118 road BBs and the what the XTR MTB crank requires.

FWIW. ALL of the Octalink BBs (and, cranks) that I have are symmetrical ... the only BB/length which I don't have is a 116mm XTR. YES, I am one of the few people (the only one?) on this Forum who likes the Octalink V1 BB.

The XTR BBs are designed for a 73mm shell, and require a spacer (two, thin, 2.5mm spacers are included with the XTR BB) if mounted in a 68mm BB shell.

The older XTR BB spindle will fit in the 68mm DA BB cups on the older BBs which are not sealed, and vice-versa ... the latter is not recommended unless you are going with a single speed set up with a 109.5mm spindle in the 73mm cups (this is only viable if the crank arms will clear the stays on the particular frame).

My recollection is that an XTR Octalink crank mounted on a 109.5mm spindle results in a 160mm Q-factor (vs. 150mm with an Octalink ROAD crank) ... maybe, it's less.