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Old 01-12-10, 09:12 PM   #1
mzeffex 
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Cracked dura ace crank?

I just picked this up used then realized this:

The green I think is supposed to be there, the red not so sure. Pictured is where the crank arm enters the spider. It is kind of raised, so is it just forging?

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Are they talking about spectators feeding the cyclists? You know, like don't feed the bears?

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Old 01-12-10, 10:01 PM   #2
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Get your money back if you can.

Assuming you have some $$$ tied up in this, if you can't get your money back and want to be sure, run it by a machine shop and have them do a penetrating dye test.
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Old 01-12-10, 10:21 PM   #3
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I had a stronglight that came apart right there, it was on my fixed and I almost hit a car. Good thing I still had a break, it just took me a second to remember it was there, and to stop wondering why I was coasting. Mine didn't fall apart though, it just spins like a free wheel now. lol
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Old 01-13-10, 06:26 AM   #4
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It's not cracked. It's part of the manufacturing process.
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Are they talking about spectators feeding the cyclists? You know, like don't feed the bears?
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Old 01-13-10, 07:49 AM   #5
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It looks more like flash then a crack. Flash is raised metal whereas a crack would not be. It's a normal result of the manufacturing process, resulting from a gap in the edge of the production tooling which allows excess metal to flow out a bit. Usually it's broken, polished or machined off later, but not always, especially in non-critical places or where they don't expect it to be visible in the finished assembly, like the back of a crank arm. Don't sweat it, enjoy your new cranks.
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Old 01-13-10, 08:09 AM   #6
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Originally Posted by mzeffex View Post
It's not cracked. It's part of the manufacturing process.
I don't agree, I think it's broken. I don't have a Dura Ace crank but I just inspected two 9-speed Ultegra cranks, two 8-speed 105's and a couple of old SR and Suguino cranks and NONE of these have any molding flash, forging marks or similar parting lines on either side of the spider/hub junction. The hub to spider transitions on all of these are completely smooth.

I can't believe a Dura Ace crank would be less finely finished than these are so I have to believe yours is cracked.

Don't use it.
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Old 01-13-10, 11:22 AM   #7
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I don't agree, I think it's broken. I don't have a Dura Ace crank but I just inspected two 9-speed Ultegra cranks, two 8-speed 105's and a couple of old SR and Suguino cranks and NONE of these have any molding flash, forging marks or similar parting lines on either side of the spider/hub junction. The hub to spider transitions on all of these are completely smooth.

I can't believe a Dura Ace crank would be less finely finished than these are so I have to believe yours is cracked.

Don't use it.
I disagree completely. The new Dura Ace (Hollowtech) is made with a different process than those earlier, solid cranks you're comparing it to. The crank is fine. Mine had it when brand-new. Shimano puts it on the nearly-invisible underside of the crank. True, the underside is not as pretty as those earlier cranks, but overall it's much, much (& much-much) lighter and stiffer.
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Old 01-13-10, 11:40 AM   #8
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I disagree completely. The new Dura Ace (Hollowtech) is made with a different process than those earlier, solid cranks you're comparing it to. The crank is fine. Mine had it when brand-new. Shimano puts it on the nearly-invisible underside of the crank. True, the underside is not as pretty as those earlier cranks, but overall it's much, much (& much-much) lighter and stiffer.
OK, I missed that it was a Hollowtech II crank. I was, as you noted, comparing it to square taper and Octalink cranks and they look nothing like the one in the picture.
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Old 01-13-10, 04:35 PM   #9
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The green areas look like casting marks. The red area looks like a crack. Get a 10x magnifying glass and look at the area. If it is a crack you will not be able to see the bottom of the area. Flashing or casting marks will be very obvious.
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