RE: [CR]Was Paletti - Now Cracked crankarms


Example: Framebuilders:Rene Herse

From: Mark Bulgier <mark@bulgier.net>
To: classicrendezvous@bikelist.org
Subject: RE: [CR]Was Paletti - Now Cracked crankarms
Date: Wed, 15 May 2002 13:48:18 -0700


Charlie Young wrote:
> Help me out here folks. I see what appears to be the crack:
>
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1829066549
>
> Is this particular crankarm toast or can it be reclaimed by
> filing down to the innermost extent of the crack?

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.

Mark Bulgier
Seattle, Wa
USA