Wednesday, September 30, 2009

A golden nugget from years ago

There's been a length debate over at about Powercranks and their effectiveness. What else is new, right? One of the big marketing claims of PCs is that you'll gain a couple of mph in speed which represents "up to 40%" increase in power. The debate has always been how much is merely training effect versus something PCs may actually do. That is, do PCs, as claimed, increase efficiency and then power? Or do they just provide the motivation to train harder and you'd get to the same place with regular cranks? Having used them, I fall into the camp that they don't work magic. If you've peaked on regular cranks, you've peaked. PCs can certainly help you hit your limit just like regular cranks, but they won't push beyond that.

So what did I find in the archives? An old threshold effort from my first month of training with power and in the first 8 months of my bike riding. A little background first:

  • I started riding around September 2001
  • I crashed in mid Feb 2002 and suffered a broken hip
  • Within 3 weeks of the crash I was on an recumbent exercise bike getting my flexibility and moderate strength back
  • Within 5-6 weeks of the crash I bought a Computrainer so that I could get back on my real bike and regain full fitness
  • Within 4-6 weeks of the crash I bought Joe Friel's cycling book and learned the basic principles of proper training methods
In late April 2002 I did a "40k time trial" on the Computrainer. Looking at the data, I went pretty hard. My heart rate during the effort averaged 157 bpm. That's in the range of my typical HR for an hour effort (155-165 depending on fatigue and/or heat); I've got a slow beating heart. My HR also got up to that level within 2 minutes. These days, after 8+ years of cycling it can take a good 8-10 minutes to reach a steady value. My HR also drops like a rock - 60-80 beats in a minute once the workload is removed.

Now my Computrainer has always read a bit low. The 40k effort was 174 W average on the Computrainer for 77 minutes and 176 W for the first 60 minutes. I have calibrated my Computrainer against a Powertap and the "correct" value for 60 minutes would be 188 W. Fast forward 8 years and my hour power is in the 275-285 W range. So my hour power has increased some 50% through training effect alone. If those Powercranks worked the way they were advertised, I should get another 40% gain for a whopping grand total of 110%!!!!!

Can someone say snake oil?


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