New D/A crankset: What BB?

[benkoostra]

I just got a 7701 Dura Ace crankset for my old Trek 1500/ mostly 105 bike. It's really just a vanity thing, since I really don't need it at all, but hey, it was cheap, so I swept it up.
I have a 105 triple BB which I'd like to use for the time being. I assume there will be no compatability issue there?

My question is this: what D/A BB model will work for this? It needs to be Octalink, but I'm not sure of the width.

Can Anyone help?

[alfeng]

I just got a 7701 Dura Ace crankset for my old Trek 1500/ mostly 105 bike. It's really just a vanity thing, since I really don't need it at all, but hey, it was cheap, so I swept it up.
I have a 105 triple BB which I'd like to use for the time being. I assume there will be no compatability issue there?

My question is this: what D/A BB model will work for this? It needs to be Octalink, but I'm not sure of the width.

Can Anyone help?109.5 is the recommended length for an Octalink DOUBLE on a ROAD bike ... BUT, with an aluminum touring frame with a 135mm rear, I found that a 118mm spindle (intende for the triple crankset) was necessary to ensure that the rings AND crank arms cleared the chain stays.

For your Trek, an English threaded 109.5mm ULTEGRA 6500 BB is the recommended bottom bracket.

BTW. On one bike, I have a 112.5mm XTR bottom bracket ... which was out of laziness, originally -- I already had the 112.5mm BB on the bike (a steel road frame), I wanted to test a triple combination ... it shifted fine onto the granny.

The 112.5mm lets me use a triple OR a double crank -- and, the only adjustment is the front derailleur's inner stop -- so, that has become my preferred spindle length.

NB. This is probably stating the obvious, but the XT/LX Octalink is DIFFERENT from the XTR/DA/Ultegra/105 Octalink.

[Tech72]

I agree, a 109.5mm ULTEGRA 6500 BB is the recommended bottom bracket for use with the D-A 7701 crankset. See attached PDF's from the Shimano website for detailed reference info.

[benkoostra]

Thank for the info.


I'll just use my 105 BB for the time being, then go with the Ultegra. No need to count grams on this bike.