11-11-2013, 01:12 AM
Looking to rebuild the entire drive train on an old frame. To start, I'm looking at the Shimano Tourney A070 double crank set. But I can't make head or tails of the spec sheet I've found for a compatible BB? Shimano's recommendation is the BB-UN26, for which there are at least 5 different lengths (from what I can tell from some additional googling).
In the "Axle length / BB spec" section, there are 8 categories, all applicable to 68mm (BC1.37) or 70mm(M36) shells:
HOLLOWTECH II construction
109.5 mm
118.5 mm
113 mm
121mm
MM107
MM110
LL113
"MM110" looks to be the one applicable to me (LL113 if I were going for the A073 triple). What are those? What do they mean? Does this tell me what the actual length of the darn thing needs to be?
The old spindle was a 3T with a double crank and is ~126/127mm (w/o the threaded bosses). This threw me for a loop, since Sheldon Brown lists 3T at 123mm...
In the "Axle length / BB spec" section, there are 8 categories, all applicable to 68mm (BC1.37) or 70mm(M36) shells:
HOLLOWTECH II construction
109.5 mm
118.5 mm
113 mm
121mm
MM107
MM110
LL113
"MM110" looks to be the one applicable to me (LL113 if I were going for the A073 triple). What are those? What do they mean? Does this tell me what the actual length of the darn thing needs to be?
The old spindle was a 3T with a double crank and is ~126/127mm (w/o the threaded bosses). This threw me for a loop, since Sheldon Brown lists 3T at 123mm...