Did my first 40k tt yesterday, 26mi to be exact and I was under geared on my fixed gear. I decided to just use 46/17 to see how I'll do on this gear and was only able to do a 21.8mph average speed with a average cadence of 103rpm. It took me 1'12" and was the most brutal race I've done so far. This has got to be the flattest 40k course around here and it sure was fast. Hopefully I'll be more prepare next time.