Thursday, October 28, 2010

Two falsehoods in the bicycling world

There's a lot of junk wisdom in the bicycling world, especially in the shops where money is exchanged for high-markup products. What I'd like to discuss today has to do with two falsehoods that have been successfully sold to the cycling world's collective conscious. I realize that this is specific information irrelevant to most person's lives, but on the other hand, this is what we've come to expect from Just Enough Craig, is it not?

Falsehood 1: Clipless pedals allow you to pull up on the pedal to generate more power.

First of all, let's all agree that “clipless pedal” is the worst name you could give to a pedal that you clip onto. For those who don't know, there are three basic pedal types: stomp, clip, and clipless. Stomp pedals are the ones you had on your childhood dirt bike; the foot rests on the pedal, and nothing holds the foot in place. Clip pedals are stomp pedals with an attached strap or cage that encloses the toe-end of the foot. Clipless pedals are the ones that require a cleated shoe and are the cause of countless cyclists tipping over after coming to a stop at red lights and stop signs.

Tipping over aside, there are many great reasons to ride with clipless pedals: they give the rider better control over the bike; they're easier to “dial in” to the right position relative to the foot; they're more comfortable. But what clipless don't offer is more power—at least not sustainable power. The salesman at the bike shop will often make a claim to a cycling newbie about how clipless pedals allow the rider to “pull up” during the pedal's upstroke using one's hamstrings, thus allowing the rider to generate more power. Sometimes the salesman will quantify the effect, such by saying “20% more power” or “one-third more power”.

This is utter nonsense. If you don't believe me, find a clip or clipless bicycle and try riding around only pulling up on the pedal during the upstroke. What you will soon discover is that it's immensely difficult to generate but an insignificant amount of power despite a generous amount of exertion. Simply put, the human body is poorly suited for generating much power with a leg-lifting movement like the one needed to pull up on a bicycle pedal. Contrast pulling up with pushing down on the pedal, where an easy effort will achieve a respectable speed. Pulling up is clearly a no-go for power generation.

As it turns out, after a few minutes of regular riding (about the time when you've stopped consciously thinking about your pedal stroke's form), you may realize that contrary to pulling up even a little bit during the upstroke, your rising foot is actually pushing down on the pedal, thus negating some of the work being done by the other leg. This is normal. But it is indeed a waste of effort, for though the body is poorly suited for generating power in a leg-raising movement, it's efficient at lifting the leg when the leg is not under load. The optimum pedal stroke doesn't involve pulling up on the pedal during the upstroke, but it does involve lightly lifting the rising leg such that the foot neither pulls nor pushes the pedal. You can do this with any of the three pedal types.

Falsehood 2: Carbon frames are more comfortable.

Ask any bike shop salesman, and you'll soon learn that aluminum is the least comfortable frame material and steel and carbon are the most comfortable. The idea behind this is that steel and carbon better absorb the small shocks of the road—i.e., jitter—than does aluminum, and so they make for more comfortable bikes.

While there may be some truth to this, whatever jitter-absorbing difference there exists between frame materials is insignificant and shouldn't factor into one's decision-making process when choosing a bicycle. People who buy carbon because of its silky smoothness are buying a bicycle made out of placebo.

A little thought about the matter reveals what you need to know. Between the pothole and the rider, there are many parts on the bike absorbing the jarring shock. From the ground up there are: tires, rims, fork and frame (and seat stay), and saddle. Most of the shock is absorbed through the tires and saddle—the “cushioned” parts. The “non-cushioned” parts, including that expensive carbon frame, absorb a small if not negligible fraction of the shock. Thus, the frame material cannot have much effect on the jitter-related comfort of the bicycle as compared to, say, replacing the tires or choosing a better saddle. This may be worth keeping in mind if you'd like to avoid buying a placebo-frame bicycle.

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