Thanks Todd-
Damon's a full-fledged engineer now, I wonder if he could come up with some kind of conversion? My part in the Holland study was just to listen to Jason's machine click all day long.
By the way, I saw a nicely-crafted stained-glass Heron piece last year in La Mesa, California and thought it would make a suitalble "greeting piece" for your doorway entrance.
Joe Starck,
Sun Prairie, Wisconsin
Todd Kuzma <tullio@TheRamp.net> wrote:on 3/13/03 1:51 PM, joe starck at joestarck2003@yahoo.com wrote:
> Todd-
> You cite below that "The ISO test requires a load of 99 lbf to be applied for
> at least 50,000 cycles at amaxmimum frequency of 25 Hz. The DIN test requires
> a load of 68 lbf to be applied for at least 100,000 cycles. For reference, the
> Heron fork was tested by Specialized with a load of 99 lbf over 250,000 cycles
> without failure."
>
> Todd-
>
> The "Damon Rinard stem fatigue test" of Holland Cycles handlebar stems,
> engineered by Jason Lilly, called for static and dynamic loads of 1651 lbf
> without failure at over 2 million cycles. I kow I'm mixing stems with forks
> here, but this stem data seems like really big numbers compared to your fork
> data. In the bicycle industry, are some tests like the gorilla in a cage with
> Samsonite luggage, and others just opening and closing a few times to check
> the hinge. How would I know what's really safe to travel with?
I think we have an apples-and-oranges situation. Damon's test gives 1651 in-lb as a *torque* (newton-meters or pound-feet) figure applied to the stem. The ISO and DIN requirements are simple *force* (newtons or pounds) figures. I'm not sure if there is a simple conversion that can be done to give comparable figures.
However, you may be correct that Damon's test might be more stringent than the ISO and DIN tests. ISO and DIN represent only the minimum requirements.
Todd Kuzma Heron Bicycles LaSalle, IL 815-223-1776 http://www.heronbicycles.com
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