Mr. Fix-it #2. 30 days of biking, #20

When troubleshooting bicycle-related issues, keep the word related in mind. It’s easy to focus on equipment to the exclusion of all else.

Like a couple of days ago when I was listening to a rider talk about his power meter.

Power meters come in different forms—pedals, bottom brackets, cranks, and rear hubs—but they all do the same thing: provide riders with feedback on their power output, usually in watts.

That feedback will vary across meters, but each meter tends to provide pretty consistent feedback over time.

In other words, if you have a bunch of riders, each one using a different power meter, you can expect one meter to be a few watts higher or lower than another. Pretty consistently.

But the rider talking to me said his power meter regularly registered a 200-watt difference when compared to that of another rider on the same ride using the same model single-sided pedal power meter.

Single-sided meters are less expensive than dual-sided meters. Dual-sided meters let riders compare each leg’s power output. Still, both riders were using the same meter. What could account for the large disparity in readings?

Let’s back up a second. The rider started the conversation by wondering whether his bike—always the oldest bike in the “fast-ride” pack—was slowing him down. He also asked whether I thought he should buy a $7,000 road bike.

I later realized that the bike discussion on top of the power meter discussion primed me to see the unexpected output readings as an equipment problem. What else could it be?

I said it would be interesting to swap meters between the bikes and see if he recorded the same big number or if the big number traveled with the meter to the other bike.

We went back and forth for a few minutes over the puzzle. Then he said something that made me realize I hadn’t considered all the variables.

He was almost always in front of everyone else on the ride for the length of the ride.

I originally heard “fast ride” and thought everybody riding was trying to outdo everybody else. But no. This was a bunch of folks drafting the strongest rider.

Well, that’s your 200 watts right there. At least in theory. Now he needs to test the theory.

I suggested he pedal at the back of the group on the next ride and afterward compare his power meter reading to some of the other riders. Maybe repeat the experiment on a couple of other rides.

I’m sure everyone on the fast ride will take long pulls at the front to support his effort to finally resolve the power meter mystery.

You know, for the sake of science.

April 20, 10.8 miles.