Rode with the regulars we normally ride with on a weeknight ride and used my TT bike. I put the HED Alps wheels on the Cervelo P2C. Somehow I wound up riding up front for probably 30 of the 37 miles. Everytime I'd look down at my HR monitor it would be around 175-180 bpm. I guess your body just tends to ramp it up when you get tucked in an aero position??? I didn't realize I was riding that hard. One heck of a workout.......