> I purchased the 175mm SR road cranks new in '85, which was close to the
last
> year of production. (They are marked 4 in a circle) Unfortunately the
> hairline crack at the spider has progressed about 1/4" so I think it's too
> late to do anything with a file. These cranks had about 33,000 miles of
> use.
Are these the later, non fluted cranks? I wasn't aware that they were prone to breaking at the spider. I have 2 pair of these in fixed gear use and have noted that the shape of the crankarm/spider interface is much different (a radiused corner instead of a more angular one) than that of earlier versions. I assumed this change addressed the stress riser issue.
When a crankarm breaks in the middle, I think the reason is often a groove and therefore weakness cut into the arm from constant front derailleur contact.
Rick Chasteen, Kansas City