Tom is correct. I should have been more clear in stating that each side of any flat area be smoothly radiused so that there are no sharp areas. As far as pre emptive stress relieving, I don't think it is necessary but you must know what to look for to determine that a crank is OK. When these were new I was riding 5K miles per year and I rode the same crank for 10 years without a problem. I became more cautious when a recently acquired used crank clearly showed cracking. After inspecting my other cranks under magnification I saw very small cracks that I had previously thought were just dirt. In those cases I decided that stress relieving was the way to go, after all these things are 35 or so years old and I don't want to have to look for a new no date crank for my '69 Cinelli.
Anyone have any thoughts on whether or not 151 BCD cranks are also susceptible to this problem?
Norm Lafleur
Ashfield, Ma.
> In answer to questions recently raised on whether it is safe to resume
> using
> the cranks after the crack is filed out. I have done so numerous times
> without incident. In fact, it is probably safe to use them before the
> crack
> is filed out. Actual failure is fairly rare (there sure are a lot of
> bikes
> being ridden with them) , I believe, but it is nice to be on the safe
> side.
> Now another writer told how he filed the crack out to form a little flat
> spot. In leaving this flat spot, one creates two new minor stress risers.
> One should gently round out the corners left from filing.this only takes a
> few seconds.I like to use small rat tail round files and to remove no more
> metal than seems called for. A really neat job would probably finish up
> with a very fine wet sand on the filed spots, but I have never bothered
> and
> other riders I know don't seem to bother with that also.
>
> Although this cracking has been brought up numerous times on this list, it
> is surprising how many unsuspecting riders you can show them to who are
> not
> list members and every one of them so far has been amazed to see them.
>
> Tom Sanders
>
> Lansing, MI USA