Monday, August 9, 2010

The PowerCam Crank Arm

Before Shimano with there Bio-Pace chainrings, we had . . . P O W E R C A M !
Yep . . . that's a 60 tooth chainring folks.

The concept is simple . . . the design, not so much. The concept is to advance the chainring during the bottom of the down stroke when your leg strength is at it's peak. Then during the up stroke the chainring retards to it's original position. Yes "advancing" and "retarding" are industry terms. Check the Science
I traded something for it a long time ago. It works fine when you have chain tension. When you don't it tends to clang a bit if you don't watch it. It was desinged for time trials more than anything. It was heavy, and I didn't see any pros like Greg leMond, Bernard Hinault, or even Francesco Moser using one, so it sits in an old cardboard box since.
Heck it might have worked, who knows, I'd never know, I followed the sheep rather than do some practice TTs on it and seen for myself. Hmmmmmmmm . . . I smell experiment . . . don't you?


PowercamFan Dave said...

Just read your interesting comments on the Ex Powercam, which I've had on my racing frame (Raysport... Cinelli copy)since 1985. Is yours still sitting in a box somewhere? My chainring side bearing cup just split off where threads end, and I'd like to find a replacement. I'll watch this blog in case you reply if in fact we can contact each other. Many thanks. BTW, I'm in Puerto Rico.


CurbDestroyer Chronicles said...

I got it used. My cups don't have races. It was modified to be setup with a Phil Wood bottom bracket. I'm not sure how hard it would be to find a replacement. I know PowerCams appear on Ebay every now and then. Get some machined. You will have to find an old aluminum cupset and take the races out of them, and then have to cups machined to those specs.