Octalink & Wider Frames ???

[DHallerman]

I know the "normal" Octalink v1 bottom bracket length for a double crank, such as a Dura-Ace (7700) or Ultegra (6500) is 109.5mm.

But what if I'm installing one of those double cranks on a road bike that also takes a 34.9mm (1-3/8 inch) front derailleur clamp.

Might I want to use an Octalink v1 bottom bracket that's 112.5mm in length, such as the BB-M952 XTR model?

Dave, who has installed only square-taper bottom brackets and cranks up to now and also thinks it quite weird that Shimano discontinued the very useful Ultegra sealed cartridge Octalink v1 bottom bracket in that 109.5mm double length

[dave thompson]

I know the "normal" Octalink v1 bottom bracket length for a double crank, such as a Dura-Ace (7700) or Ultegra (6500) is 109.5mm.

But what if I'm installing one of those double cranks on a road bike that also takes a 34.9mm (1-3/8 inch) front derailleur clamp.

Might I want to use an Octalink v1 bottom bracket that's 112.5mm in length, such as the BB-M952 XTR model?

Dave, who has installed only square-taper bottom brackets and cranks up to now and also thinks it quite weird that Shimano discontinued the very useful Ultegra sealed cartridge Octalink v1 bottom bracket in that 109.5mm double length
Using Serotta as an example of a bike that has uses a 34.9MM dérailleur clamp, they still use the standard width bottom bracket shell and the "normal" OctaLink 109.5 bottom bracket spindle length.

[pdxmech13]

Seat tube has no effect on BB shell in this case.

[maunahaole]

Seat tube has no effect on BB shell in this case.

+1

BB shell is still wider than seat tube. I have a 35mm fd clamp on my current ride and just put in a 102mm bb and it works fine (probably better).

[DHallerman]

+1

BB shell is still wider than seat tube. I have a 35mm fd clamp on my current ride and just put in a 102mm bb and it works fine (probably better).

When I posted initially, I was thinking of variations in bottom bracket length with Campy cranks.

For example, with the most-recent square taper Centaur cranks, the 111mm bottom bracket was suggested (by Campy) with 1-1/8 inch and 1-1/4 inch seat tubes, but the 115mm bottom bracket was spec'd for 1-3/8 inch seat tubes.

So, I thought, if there's variation in bottom bracket length, based on seat tube diameter, with those Campy cranks, why not with Shimano Octalink.

Dave, who knows logic doesn't always work even with something that seems like it should be logical such as bike mechanics