Charlie Young wrote:
> Help me out here folks. I see what appears to be the crack:
> 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.