With all the fuss regarding pedal crank breakage, here is a wierd tidbit we just learned of that is sorta related to it. In 1983 or so Campy INCREASED the size of its pedal threads and also increased the diameter of the pedal hole in the crank. The argument was that it was done to make Campy similar to other cranks.
We discovered this upon reading an enclosure in some Chorus platform pedals claiming that the pedals Would Not Work with Campy NR/SR/Victory/Triumph/C-rec cranks. We then spoke with an employee at a large Campy wholesaler who used to work for Campy USA who explained the story. In theory, use of a large spindle could cause stress on the arm and possibly lead to failure. Assuming that Campy stuck with this, then use of any later pedal such as a modern Campy clipless in one of these cranks should also be taboo! Are we oblivious, or has anyone else known, learned of, or cared about this? From experience and observation, this rule from Campy is/was violated continously.
On another note, our experience from talking to folks is that Campy NR/SR cranks usually break near the pedal spindle and most often on the left side. They will break at the spider stress riser, but nearly every used Campy crank we've ever seen has a crack there - at least 85% of all used ones I'd say have some crack action.
If I'm not mistaken, one should simply try to file ahead of the crack or keep an eye on it, and when it is really starting to show the arm should be discarded. Anyone who continues to ride a Campy crank with a really pronounced crack - and is aware of it - is simply providing more evidence that Darwin was right.
Mike Kone