And my point Joe, is that old steel cranks can and do fail at the pedal eye just as do old aluminum cranks that fail at the pedal eye (as I said).
Reread Don's conclusion again...
Chuck Schmidt South Pasadena, Southern California
Joe Bender-Zanoni wrote:
>
> Don's point is that with steel, the the cyclic stress is low enough, there
> will be no failure no matter how many cycles the article is subject to. This
> is not so with aluminium.
>
> To design this way for steel I vaguely remember you use a "Goodman Diagram".
>
> Joe Bender-Zanoni
> Great Notch, NJ
> "More confidence in 75 year old BSA cranks than 25 year old Campagnolo"
> ----- Original Message -----
> From: "Chuck Schmidt" <chuckschmidt@earthlink.net>
> To: <classicrendezvous@bikelist.org>
> Sent: Thursday, September 16, 2004 3:28 AM
> Subject: Re: [CR]Campy Crank breakage and missing point
>
> > Donald Gillies wrote:
> > >
> > > Richard has a good point about aluminum crank failure. Aluminum has
> > > no lower fatigue limit. When you have applied XYZ stress cycles of
> > > force PDQ, and F(XYZ, PDQ) > max, the crank WILL fail. Steel has a
> > > lower fatigue limit - if you can keep your stress cycles below this
> > > limit, a 531 steel frameset will last forever.
> > >
> > > In other words, in 100 years we may still be riding our cambio corsa
> > > bikes, but by that time all the nuovo record bikes will be TOAST.
> > >
> > > - Don Gillies
> > > San Diego CA
> >
> >
> > Well not exactly, as there is plenty of documentation of steel cranks
> > failing at the pedal eye just as aluminum cranks do.
> >
> > Crank failure is very low on my list of things that can or will harm me.
> >
> > I've always maintained my equipment as if it was a light airplane and
> > inspected for cracks whether it was something made from steel, aluminum
> > or carbon.
> >
> > Chuck "life will kill ya" Schmidt
> > South Pasadena, Southern California
> >
> > .