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?
Joe Starck
Sun Prairie, Wisconsin
Todd Kuzma <tullio@TheRamp.net> wrote:on 3/13/03 11:56 AM, MSCTROSE@aol.com at MSCTROSE@aol.com wrote:
>
> In a message dated 3/13/03 9:24:25 AM, goodrichbikes@netzero.net writes:
>
>
>> I've also had my brazing tested by several independent testing facilities.
>> Joe Starck and I built many forks for Rivendell for testing of a new fork
>> crown. It was quite interesting.
>>
>
> Curt
> Please tell us the testing procedure. Inquiring minds want to know. Is
> this procedure done for >gasp< modern, off topic, factory made forks as well?
There are DIN and ISO standards for dynamic fork fatigue. The fork is mounted in a test fixture. The steerer is held in a fixed position with a full headset. A loading attachment is clamped in the dropouts. The ISO test requires a load of 99 lbf to be applied for at least 50,000 cycles at a maxmimum 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 Kuzma Heron Bicycles LaSalle, IL 815-223-1776 http://www.heronbicycles.com
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