Friction Bad, Power Good

Finally I've stumbled on something truly amazing. Even my wife, who frequently rolls her eyes at my equipment priorities, agrees that the VCRC ceramic bottom bracket is just freakin' cool! Bear in mind, I've ridden on this apparently friction free BB for fewer than 100 miles but - well DAY-UM! After the missus installed it I spun the crank (with the chain off). That was two days ago and I think if I hadn't stopped the crank myself it might still be going around. She's getting one.

Skeptics will tell you that the amount of drag produced by a crank just isn't enough to matter, but I disagree. Most people who care about such things put the absolute mechanical efficiency of a racing bicycle at around 95%. For what it's worth, here's my opinion based on degrees in engineering and physics, and a lifetime of bicycling. I'd rank the friction penalty of components in the following order: bottom bracket, deraileur pulleys and wheels last. This is not a statement about the importance of the component perse, but rather that manufacturers have actually paid some attention to wheel friction, and not the other factors. Even moderately priced wheels spin pretty freely, but some really pricey cranks don't.

Back in the late 70s an engineering grad student told me that derailleur pulleys were most important (bear in mind, this was in the day of cup-and-ball BBs so they were much slicker than today's sealed models) and the difference could be about five watts or more. Thing is there are fairly cheap ball-bearing jockey pulleys for $10-15 which eliminate most of the friction compared to the ones with bushings. That's the way I've gone, mostly because my wife would surely believe me insane for blowing $80 on derailleur pulleys. I crunched some numbers and concluded that in a 15 second sprint over 800W that every five watts translates to 0.5 meters at the finish line. That's why basically every pro has ceramic bearings in their cranksets and I suspect in other components as well.