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Old 11-07-07, 03:52 PM   #1
Marc7200
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Changing from square taper to Shimano Octalink Bottom Bracket question

I am wanting to upgrade my crankset and replace the bottom bracket on my mountain bike. I have been looking at the Shimano Deore crankset and it uses an Octalink Bottom Bracket axle. If I measure the axle on the square taper bottom bracket I currently have will the proper Octalink bottom bracket be the same length?
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Old 11-07-07, 04:22 PM   #2
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Measure the BB shell.
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Old 11-07-07, 04:36 PM   #3
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yes, measure the axle too. Or just take the old one with you to the shop they'll have no problem matching it. You're expecting the shell to be 68mm or 73 mm. The axle length will be something between like 103mm to 125mm. The first is to ensure it fits in your bottom bracket shell and the 2nd is to ensure your chainline remains the same.
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Old 11-07-07, 06:57 PM   #4
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Answer to your question: NO (unless it's just a coincidence)

Square taper axle length =/ octalink axle length. The spindle (axle) length will be determined by your new crankset.
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Old 11-07-07, 07:00 PM   #5
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Quote:
Originally Posted by vpiuva View Post
Answer to your question: NO (unless it's just a coincidence)

Square taper axle length =/ octalink axle length. The spindle (axle) length will be determined by your new crankset.

+1
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Old 11-07-07, 07:03 PM   #6
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Threre are three key bottom bracket dimensions.

The first is shell diameter and thread pitch. That one's easy. You need an english BB.

The second is BB shell width. I'm 95 % certain you need a 72mm shell width. Measure your frame to be 100%.

The third dimension is spindle length. That's mostly determined by your crank profile. Most Deore cranksets sugggest a 113mm Octalink V2 BB spindle.
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Old 11-07-07, 08:40 PM   #7
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I had a problem when going from square to octalink cranks.
I pulled the old shimano square taper BB out (68x113) & even ordered the XT octalink BB 5mm longer (68x118).
I ended up using a LX BB that was 126 long.
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