Does weight matter?

I say: No and yes. "No" in that weight will have a minimal effect on the general rider, especially one who doesn't care about performance. Also, in terms of our discussion, "no" in that folding and non-folding bikes are usually very close in terms of weight anyway.

"Yes" in two senses. One in that for an elite handful (specifically, pro racers), 3 seconds at the end of a 40 mile time trial can be the difference between 1st place and 20th. Two in that if you have to carry the bike up a flight of stairs or onto mass transit, a lighter bike is much more convenient.



At the risk of a bit of repetition: the primary issue, which I think you're starting to understand, is that weight only matters when you're accelerating. Once you have achieved a specific velocity, though, the force that will slow you down is friction: drag (which is the largest factor), rolling resistance and drive train efficiency.

The trick is, you aren't spending a lot of time accelerating, and the effects of 10 pounds to a system that totals, say, 150 - 280 pounds is small to begin with. Most of the time you're trying to maintain a certain speed.

This is why you can have strong and consistent subjective experiences that a heavy bike is slow (because it doesn't accelerate quite as fast) or that small-wheeled bikes are more fun (because they do accelerate faster, and that can be more pleasant). However when you add everything up, because you spend so much time at a more or less constant speed and fighting drag rather than gravity, the slower acceleration actually winds up being less significant than it feels.

By the way, drag has an impact at all speeds. It's the biggest opposing force you're dealing with as a cyclist. It is more significant for riders with higher power outputs (or, to be specific, higher power-to-weight ratios) because they are riding faster. However, drag is still far, far more important than weight even at slower speeds. [FYI the Kreuzotter does account for this, as you can modify the rider's power output.]


As to objective measurements: A HRM does objectively measure the rider's exertion. However, this is not necessarily going to be a consistent factor, because your cardiovascular abilities can change from day to day -- especially if you happen to be training. I think you'd need a pretty large pool of samples to try and correct for this.

The reason why a power meter will be more objective in terms of measuring a bicycle's performance is that it precisely measures power output, which is what is propelling the bike. It doesn't matter if it's a pro or an amateur or a robot, 200 watts is 200 watts is 200 watts.

So if you know that Bike 1 travels at 15mph when the rider applies 200 watts of power, and Bike 2 travels at 16mph at 200 watts, and the environmental conditions are consistent between tests, you will know exactly which bike performs better and by how much.


Ergo, in terms of the myths: Although I haven't proven it using objective tools, from what I know the performance differences between 20" and 700c bikes are usually a wash. The smaller wheels are faster, but less comfortable, so the designers almost always adjust for this via methods that induce a performance penalty that, in most cases, is acceptable to the rider.

So the myth that "you have to pedal more" or "smaller wheels must be slower" are incorrect, while "smaller wheels are harsher" is true specifically when you are comparing equivalent tire types.