RE: [CR]Was Paletti - Now Cracked crankarms

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content-class: urn:content-classes:message
Subject: RE: [CR]Was Paletti - Now Cracked crankarms
Date: Wed, 15 May 2002 17:10:35 -0400
Thread-Topic: [CR]Was Paletti - Now Cracked crankarms
Thread-Index: AcH8UVb3iyQ2kGLzSE2MgKcAl2prjQAAGIAg
From: "Bingham, Wayne R." <WBINGHAM@imf.org>
To: <classicrendezvous@bikelist.org>



>>>>Mark Bulgier wrote:I'd expect that is salvageable. I've filed and ridden worse anyway. But other than armchair cogitatin', I don't have any real evidence of the lifespan of cracked cranks, with and without filing. Anybody else have anything more definitive?

I use a tiny needle file (about 1/8" diameter; that's 3mm in Communist countries ;^), file all the crack out, then round and fair all the edges where I filed, then smooth out the filemarks, usually with something like 220 grit paper or cloth followed by 400 grit. I do believe that filemarks are coarse enough to be stress concentrations that might initiate a crack down the road, even from my fine needle file. Ideally the whole area would be polished, but I stop where I imagine the point of diminishing returns to be. I haven't done it lately, but I imagine it's about a 20-minute job, and it's worth it to me if only for the placebo effect.

I'd love to hear others' methods and results.<<<<<

I would agree that the crank arm in question does, indeed, look to have a crack, and I would also agree with Mark on his corrective measures. I've done the very same thing several times, and I use almost the exact same method. The only difference is that I use various shapes of jeweler's files, but the rest of the process is pretty much the same. A Dremel tool with a polishing wheel works for polishing it out completely, if you really want to take it that far (I usually don't). I'm about to do the process again on a crank arm intended for another project. I'll have no qualms about riding it, but I don't anticipate that the crank will see a lot of new miles either. I've also done the process on "rider" cranks prior to any evidence of cracking, just as a preventative measure. In those cases, since there is no existing crack to file out, I just slightly smooth out and "soften" the problem area. I've never witnessed further cracking on "modified" arms.

Of course, I'm not offering any guarantees here, either!

Wayne Bingham
Falls Church, VA