Techno-weenie-talk

The results of several bike traumas decided to reveal itself Saturday. It made for another frustrating weekend in a series.

While considering replacement options I found this article which has a lot of information in it, some shinola and some ...

This

There is no limitation because carbon has a natural flexibility. It can be used a hundred years while maintaining the same stiffness.

--Ming Tan
Look Bicycles

sounds a bit like sales-mo-bable, gotta love those sales guys. This on the other hand sounds more reasonable.

ASTM standards call for a load of 170 lbs. applied perpendicular to the steering axis, both pushing and pulling for 50,000 cycles without failure. At True Temper, every Alpha Q model is tested to 250,000 without failure before a design is considered acceptable. Also production models are tested periodically for quality control.

--Bert Hull
True Temper Sports

But if you read it carefully and know a little about materials fatigue testing (I've had just enough training to be dangerous) you can guess that the test loads are applied smoothly (probably a sine wave). Now it doesn't take a genius to figure out that the loads on your fork while riding are not controlled or applied smoothly and that can make a significant difference in fatigue life.

Most of the manufacturers were wise enough to differentiate between normal fatigue and impact (like a crash). Some recommended visual inspection for damage, others were more cautious.

Whenever a carbon "part" has crashed, even if you cannot see a failure, if there is any reasonable doubt about having surpassed the elongation limit, the part must be replaced.

--Fulvio Acquati
Deda Elementi

But what does that say about those pot-holes we're unable to avoid? Those sections of road in central valley races that we choose to ride? That occasional curb jump? Aren't those impact?
in his Road Bike Maintenance book, Lenard Zinn recommends regular inspection and shares this practical wisdom.

A new fork is cheaper than emergency room charges, brain surgery, or an electric wheelchair.