OK...I thought Bobby J only used these for time-trials...but he was using them today for a climbing stage in Paris Nice.
He's doing well on these chainrings. I am getting a bit interested in trying them out. They have an elliptical shape(similar to the old Biopace but there are critical differences between the two) and they are supposed to eliminate the deadspot in the pedal stroke.
when the tour was on, the frenchman who made Bobby's was interviewed about them. He said that all other things being equal, they added about 1 kilometer per hour onto the riders speed on the flats and about 1.5 on any climbs, so, assuming he was right, they help out a little more going uphill.
Anyone know anything about availability here in the states?
Available direct order from the manufacturer here, pricey but they also do some custom work if you want.
They are much more expensive than Biopace. An important distinction though-they are oriented 90 degrees out of phase from Biopace. A smoother torque curve than Biopace but not as much accelerating prior to the dead spot to propell you past the dead spot.