CAN TECH IMPROVE YOUR PEDALLING?
Many riders are turning to bike technology to find a pedalling advantage. Gearing, crank lengths and oval chainrings are frequently experimented with. Oval and elliptical chainrings aim to decrease the time you spend in the ‘dead spot’ where you are not producing power. Champion time triallist, CW ’s Michael Hutchinson, paid close attention to such innovations throughout his racing career: “I used Osymetric rings for 13 years. I liked how they felt.” Osymetric rings are not simply a different shape, as importer Train sharp stresses: “The Osymetric chainring is not an oval or an ellipse chainring — it is a unique patented twin-cam [two curves symmetrical about a single point] chainring designed to eliminate the dead-spot that is part of every cyclist’s pedal stroke when using standard chainrings.”
For Hutchinson, the improved feeling wasn’t sufficient: “We did some experiments on the treadmill using Osymetric and an identically-sized round ring. It didn’t make any difference to oxygen uptake one way or the other. We didn’t test every single aspect of the rings, so there may be some benefit that we didn’t identify. However, I kept using them, as they felt good to ride, which in itself may be an advantage.” Research into oval chainrings has, like Hutchinson’s experiment, proved inconclusive.
Crank length is a perennial discussion in the time trial world. “I rode 170mm, 172mm and 175mm — I couldn’t tell the difference,” says Hutchinson. “I’m pretty confident I could change the saddle height by a similar amount and not even notice — it’s such a small margin. Are my legs exactly equal in length anyway? To make a difference, you have to make a much more extreme change.”
Hutchinson offers an anecdote to support his case: “Chris Boardman in the summer of 1990 rode around with one 170mm and one 172mm crank because he’d stopped concentrating when he put the bike together — and in that time broke the national ‘25’ record!”
Homing in on a single component as a way to improve pedalling efficiency may be a waste of time, warns Hutchinson, as the potential for improvement is relatively small.
“There is so much variability in the drivetrain: you’ve got chainring, gearing, crank length, wheel size — and to some extent they all compensate for each other. There is very little advantage to be gained from tweaking one element.”
The exception may be crank length — not because of its direct influence on pedalling, but because of its role in bike-fit, determining how your body works on the bike. Phil Burt advises: “Muscle-shortening velocities do change if you alter crank length — but only at the extremes (120mm and 220mm). Even here the changes can be accommodated without a change in efficiency simply by altering your pedalling rate or the gear you ride in.” Small changes to crank length are “negligible because it can be compensated for”.
Burt continues: “Crank length is an important bike-fit parameter for reasons other than pedalling efficiency (for example, hip closure). Riding smaller cranks can open your hip angle up without changing any other fit coordinate (other than saddle height, for some).”
Changing crank length may not change your pedalling efficiency but it might put your body into a better riding position.