Monday, July 27, 2009


Well, I finally broke down and ordered a PowerTap hub. This nifty little cycling computer calculates power output via strain gages inside the rear hub, which translates torque into power. The obvious question is why anyone needs such a device.

Training has evolved over the years and several schools of thought exist. Ideally one would develop a base level of fitness and then begin to do targeted workouts to improve speed or lactate threshold or whatever other fitness indicator you choose. At times training was done based on perceived exertion, for example conversational pace, hard, very hard. With the introduction of heart rate monitors, the next level was achieved and through a combination of testing and monitoring heart rates during workouts, individuals could train more efficiently. Power measuring devices go a step further as heart rate measurements are contaminated by temperature, hydration, and fatigue levels. Power measuring devices for cycling have been available for over a decade, but are finally approaching the cost points that mere mortals can afford them.

The first ride was pretty exciting and I was able to focus on the road in addition to the instantaneous power which fluctuation between 120-150 watts on the way out and 80-100 watts on the way back. My average for the 20 mile ride was 123 watts which is well below world class or even trained athletes. I am really excited to have a baseline and intend to set up power thresholds via time trial efforts.

I was very pleased with the PowerTap Comp. The comp is the entry level wired device and the wireless and fully featured models can cost over twice as much. It was very easy to install and set up. I did have two small setbacks. First, I thought I had no output from the hub. It turns out that I just did not seat the receiver completely. Second, I had a difficult time having the head unit detect my heart rate. It turns out this requires setup sequence 5, and a button sequence to have the head unit “learn” the coded output from my Garmin 305 chest strap.

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