What size Bottom Bracket please?

sinnett177

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What is the correct length if using Shimano Deore LX M560 21 speed (the low profile crank version). BB size is 68mm.

Many thanks Mark.
 
I don't know, but may I just broaden the question a bit just to attract more attention?

I always thought the bottom bracket size was determined by the chainset, but I've been trying to get an 8-speed system (M739 cranks + 68/110 UN72) to work with a Mega9 LX M580 FM (it was all I had lying around) and I've come to the conclusion that the M580 FM needs a 113 BB.

I knew before that splined Shimano cranks need a 113 BB, but I thought that was just about the difference between the splines and square taper, I didn't know that the FM could affect what BB you need. But measuring the M580 alongside an M739, the distance between the clamp and the derailleur cage is c2mm greater on the M580. Which explains why I couldn't fiddle it to work without fouling the chain in the granny ring, but it looked as if it would have been ok with a longer BB. Can anybody confirm that please?

And I think an M560 also needs more than 110 doesn't it, but don't know how much.
 
I knew before that splined Shimano cranks need a 113 BB

Hold on their Anthony not always true, one version of LX Octalink actually need a 121mm and a lot of full sus bikes and a few hardtails need a 118mm to get the proper chainline on the standard Deore/XT octalink cranks.

Think its still mainly the cranks that determine the axle length, but chainstay clearance also seems to affect it too
 
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