Cycling Findings #1b

Interesting research from the cycling science literature

Effects of saddle height on economy and anaerobic power in well-trained cyclists Peveler and Green, 2011

Bike fit is a crucial aspect of cycling, both for maximizing performance and minimizing the risks of injury. And probably the most important single component of bike fit is saddle height. There are various methods used for determining optimum height, including the heel, LeMond, and 109% inseam methods. However, the most direct method is to measure a precise knee flexion angle at the maximum extent of the pedal stroke. The current experiment complemented previous ones in determining the optimal knee angle for performance.

This study took it as well-established that the safe range of knee angles is 25°-35°, but investigated whether there were any differences in performance between the lower and upper end of this range. It had been shown earlier that the 109% inseam method leads to wildly variable knee angles (from 19° to 44°, and outside the recommended 25°-35° range more than half the time), presumably due to inter-individual variability in femur, tibia and foot lengths.

There were indeed differences, albeit fairly small. Two tests were performed for each knee angle, measuring economy and power. The economy test consisted of 15 minutes of pedaling at fixed resistance and cadence, measuring oxygen consumption as an indication of economy (lower oxygen consumption indicating greater economy). The power test consisted of a 30 second maximal effort. The subjects were well-trained males.

There were small but significant differences favouring 25° over 35° in oxygen consumption (1.0%), perceived exertion (3.5%) and mean power (2.7%). Like I said, these differences are quite small — likely unnoticeable for the recreational cyclist — but potentially significant during an actual race. Certainly, people do all kinds of crazy (and expensive) things in an effort to gain a couple of watts, so potentially getting some for free seems like a good deal.

economy and power trials

The study excluded a high number of subjects, and so ended up being quite small, so I'd definitely like to see a larger one looking at multiple knee angles around 25° in future, and another thing that would have been very interesting would be a follow-up of athletes a few weeks later. There was no indication in the article about what the prior knee angle of each athlete was and therefore no way of knowing how different a particular angle was from their usual angle. If 25° was a significant departure from normal, having the athletes continue to train and race using this 'optimum' knee angle might actually increase the observed gains as they got used to the new setup.

#bikefit #saddleheight

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