Originally Posted by
rpenmanparker
Very interesting. A quick search uncovered at least two articles reporting testing that showed 5 or 6 time the sole stiffness in carbon composite shoes to plain "plastic shoes" That is likely a comparison of best case and worst case, but it is still impressive. Where the glass-reinforced nylon soles would be on this scale is hard to say, but surely somewhere in between.
What was really interesting was the observation that the stiffer the sole, the greater the stress on the plantar fascia part of the foot very possibly leading to pain and damage. I haven't heard that mentioned before. Once again I wonder how insoles modify this and how they would do it relative to their effect on the desirable aspects of ultra-stiff soles. Here are the links to the articles I found:
http://www.tulane.edu/~sbc2003/pdfdocs/0405.PDF
The effects of cycling shoe stiffness on forefoot pressure. - PubMed - NCBI
Those two links are to the same study.
what I don't get in that study is how they determined plantar pressure was a problem. The graph shows increased plantar pressure corresponding to increasing wattage output...as would be expected. If they just snatched the 400w pressure measurement out of a data series that went to 600w, wouldn't the pressure necessarily have to be higher at 400w in order to achieve 600w, than the pressure required to achieve a terminal, or near terminal, 400w?