Found a like-new Sugino triple crank I want to use. It's stamped "XD2" inside the arms. Anybody know what size BB I would need for a 45mm chain line (middle ring)?

It's for a 68mm shell (Soma "Double Cross").


Thanks!

Sheldon Brown's Bottom Bracket Size Database

Sugino XD2 Crank, Triple 46x36x24

Rivendell sells these and this is what they say:

I saw these sites but nobody gives exact chain line for a particular BB size.

Setting up a crank and a drivetrain is about more then just chainline specs. I agree that matching chain lines are a good goal but not written in stone. Clearance for arms and stays, for rings and stays take first priority. Any spindle length I read of is but a starting point, sometimes it needs to be different from claims. Andy.

I use that crankset on a Surly Cross Check, similar to your Double Cross, with a 130mm rear hub. I use a 110mm bb. I have not measured it, but it seems to line up the middle ring very nicely with the center cog of my 9-speed cassette. If you are using a 135mm mountain hub, I expect you will need a 113mm bb.

+1) Chainline in the front is dependent on what the chainline measures in the Back .

something Yo may have to calculate Yourself.

Exact chainline is unnecessary, especially for a derailleur-equipped bike. Reasonably close is what you want, with clearance between the chainring and frame and ability to run smoothly in all gears.

Sugino themselves say to use a 113mm BB and that you'll get a chainline of 47.5mm with it. My preference is generally to use a shorter-than-spec BB in order to work more of the cassette from the big ring, but I do that knowing that I may get it wrong and need to swap back to another length in order to have enough clearance everywhere.

So is it certain that different spindle lengths differ the same amount on each side of the spindle?

If so, either 107 or 110 seem to be OK for a 45 mm chain line:

107 --> 47.5 - 3 (difference from 113 bracket on one side) = 44.5 chain line.
110 --> 47.5 - 1.5 (") = 46 chain line.

107 being "most ideal."

From what I've read on the Sheldon Brown blog, Shimano's 110 is something of an oddball, having extra length on the NDS. I would go for the 107, personally.