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Question re square taper bb axle lengths

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Question re square taper bb axle lengths

Old 10-04-18, 11:00 AM
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Kapusta
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Question re square taper bb axle lengths

When looking at square taper cartridge bottom brackets, are axles of different lengths "centered" the same?

For example, If I am looking at two Shimano UN55 BBs (68mm shell), and one is 110mm axle, the other 115mm axle, is the extra 5mm width of the 115mm one added equally to both ends? In other words, are both the drive and non-drive side pushed out 2.5mm? Or does the extra length favor one side? My assumption has always been the former, but I wanted to be sure.

Thanks.
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Old 10-04-18, 11:13 AM
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Everything you want is in this thread that I started 12 years ago.
I should go and edit the OP so it includes all the info later down in the thread, but the thread isn't too long.
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Old 10-04-18, 01:07 PM
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Originally Posted by TallRider View Post
Everything you want is in this thread that I started 12 years ago.
I should go and edit the OP so it includes all the info later down in the thread, but the thread isn't too long.
Whoa!

Thanks.
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Old 10-04-18, 01:46 PM
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Originally Posted by Kapusta View Post
Whoa!
Thanks.
I just edited the final post in the thread I shared with you, to include the full list with updated information, checked against other sources. So, refer back to it and scroll down the thread to the last post.
I'm always surprised there's not much discussion or official listing of this issue, but then most people aren't super-anal about chainline (which manufacturers have seemed to care less about in modern integrated BB designs, thinking it doesn't matter a ton).
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Old 10-05-18, 03:48 AM
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Originally Posted by TallRider View Post
Everything you want is in this thread that I started 12 years ago.
I should go and edit the OP so it includes all the info later down in the thread, but the thread isn't too long.
Very nice info, thanks.

I just got a donated bike in with a 7 speed rear and a single sprocket on the crank. The chain will not stay on in the lower ratio rear gears.

Hmmmm ...I'm wondering if someone in the past did not reassemble 3 piece crank correctly thus the chain line is off.
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