Two Wheel Blogs

The secret is out. Now you know what those things that Unit cooked up really are.

In case you missed it, here is Andrew Coggan's explanation.

And here's a little background on how it all came about.

It all started a couple of weeks ago when Andy invited me over to mount up my bike on his Velodyne and have a go at Torque Analysis. I have the SRM with the on-line option, but the Torque Analysis function is yet another step in SRM's offerings. Andy has Greg Steele's SRM Power Control IV with the Torque Analysis option on loan. Andy knew about my struggles to overcome back pain because I'd asked him for a recommendation of a local professional to work with way back when my whole back injury started. I think he may have been as curious as I was to see whether my back problems were a result of, or maybe had resulted in, any interesting torque patterns in my pedaling stroke.

The answer there was a resounding no. Interestingly enough, Torque Analysis of my pedaling stroke revealed that I had the most symmetric torque curve of those tested. (Yes, I was rider #3) Note that's not the same thing as saying my pedaling stroke is the most symmetric.

The SRM, as accurate as it is, can only do Torque Analysis at the crank level. That means it cannot differentiate between the two crank arms contributing to the torque being applied to the crank. Two equally strong legs firing a symmetrical fashion will produce a symmetrical torque curve. But it's also possible to generate a symmetric torque curve with a strong leg and a weak leg. All that's required is for the strong leg to help the weak leg's side of the curve by adding in a little torque at the right time. In the case of riding a bicycle, that might mean simply that the strong leg un-weights the pedal slightly more than the weak one.

The only way to see the true differences is by isolating legs. The best way to isolate legs on a bicycle is through one-legged pedaling. The way to get as close as possible to true pedaling form using only one leg is to replace some of the torque provided by the missing leg so that the working leg doesn't have to do all the lifting.

I discussed the best way to build weighted pedals with Andy, and then turned around and brought the idea to Unit. He immediately tossed my idea out the window and replaced it with the much more elegant solution he posted about earlier. Unit's a man of action. He immediately went about the task of building this pair of monster pedals from an old pair of platform pedals and approximately 50 pounds of lead, melted and formed into 4 bricks with the mold he built especially for this purpose.

The next step in our little research project will be to mount these pedals and use Greg's SRM with TA to look at our torque curves generated from single leg pedaling only. Stay tuned. We may be able to collect data this weekend, schedules permitting.

Update:
If you'd like more background on the topic of Torque Analysis and how the SRM with Torque Analysis works, Greg Steele has a few great pages up on his site to run it down for you:

This one's about Greg's experience in getting the SRM with Torque Analysis up and running. And I really like this article in which Greg tested the impact of Rotor Rings and rear-set cleats on torque