Bicycle Mechanics - Shimano bottom brackets symmetrical?
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12-14-09, 06:41 PM
I spent an hour or so in the archives but wasn't able to find a straight answer. I also checked the Shimano website. Are Shimano square taper sealed bottom brackets symmetrical?(specifically UN54) Example: To move my chainline in 4mm I'd have to go from a 115mm to a 107mm. Thanks.
12-14-09, 08:12 PM
That is correct.
Note 110mm = 107mm in terms of chainline.
12-15-09, 01:27 PM
I just measured most of the bottom brackets on hand here at the store:
Some of them aren't actually symmetrical, but your assumption re: 115mm vs. 107mm is correct.
12-15-09, 04:23 PM
12-15-09, 08:37 PM
I'd started some threads and gotten a bunch of measurements on Shimano square-taper BB's awhile back, but don't remember what was what. You can search for threads started by me, with "bottom bracket" in the thread title.
I do remember that 107 is symmetrical and 110 isn't (having 3mm longer non-drive-side extension) as operator notes.
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