PMK

Without jinxing us, since we ride a carbon fork, I was wanted to share some information I learned this past week while attending SAMPE, pretty much an industry trade show for aerospace composites and other industries (sporting goods, racecar, medical, etc) that utilize high end composite materials, with lectures and so forth.

One of the sessions I attended, and expected an aerospace topic based on the session title, was a pleasant surprise. The presenter opened his topic and explained that this would be in regards to carbon fibre bicycle forks.

In typical engineering fashion, there was a planned set of goals and theoretical data to show possible expected results.

The primary focus area was in regards to the carbon crown area. This was on a single bike style fork with a a full carbon fork (blades, crown, steer tube).

After some slides on dimensions, loadpaths, CG, rider weight and speeds, some resultant data was presented.

The data was then applied into a graph of sorts to illustrate expected loads induced onto the fork crown at given speeds vs given road feature defects.

The theoretical end was one of the emergence of a defect (I believe it was a 3mm x 6mm defect) and how it would ultimately reduce the strength.

This was not lab tests where forks were actually tested, rather an information project that began to emphasize quality manufacturing, with no built in defects at manufacture. Also, mentioned was the importance of the manufacturer to test designs and sample forks to ensure good quality control.

Suffice to say, for all inspections done to OUR fork, these will be accomplished with a proper tap test, with the fork loaded with the disc brake applied. Thereby, putting a slight amount of deflection into the fork, to make any defect more apparent.

During the Q&A time after the presentation, it did become apparent that this is an area where one should consider a quality component from a reputable manufacturer.

As a side note, I have read here on BF that there was a similar study done where forks were lab tested. I have never seen those results and wonder if they are available.

In summary, inspect your fork, and composite wheels. The loads on these items get crazy high on singles...tandems I suspect are no doubt beyond doubly worse.

PK