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Old 07-31-11, 04:15 PM   #1
ghostm42
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Octalink crank arm splines stripped

I have a used Specialized Allez bike. I believe the crankset is a Shimano 105 Octalink v1 double (rebranded with Specialized logos). While riding today, my right foot pushed down, but my left foot did not rise correspondingly. Pulling out the crank arms, I notice the drive side splines were full of aluminum fragments. The BB spindle, however, looked just fine.

Of course, I'll have to replace it. But I'm curious, is stripping the splines off Octalink v1 cranksets typical? I don't really want to buy another crankset just to have this happen again. Or did I likely do something wrong? Put too much torque on the pedals? Overtightened the crank bolt? I'm not sure what could have caused this.

The alternative is changing the BB to another system. I'm tempted to go back to square taper since they are cheap and have been fairly reliable for me.
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Old 07-31-11, 04:23 PM   #2
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This type of failure is very rare. I doubt it had to do with excess torque unless you weight 400#s and stood on a hard climb. My best blind guess is that rather than being overtightened, you were riding it slightly loose for a while and slowly shaving the splines until they let go.
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Old 07-31-11, 05:38 PM   #3
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Also, your Specialized crankarms wouldn't be made by Shimano. Octalink crank bolts should be very tight, so overtightening them would be quite a feat... I think FB has it, they probably were not tight enough.

When you get your replacements, make sure the crank bolts are seriously tight. Octalink's designed to swedge on and then bottom, not just swedge until they're "swedged enough" like square taper.
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Old 07-31-11, 06:43 PM   #4
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you're right. they are "Specialized Pro, 39/53 teeth" according to bikepedia:
http://www.bikepedia.com/quickbike/B...uble&Type=bike

Ok. I'll look into new octalink crankarms then.
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