this is kind of a continuation of the thread about math and wind tunnels that dan started and that got really long and rather bitter. i’m just throwing out questions; let’s keep this peaceful. i know that there are no perfect answers because of how many variables there are involved, but i wanted to see what kinds of ideas people have.
so, as one who stopped after a year and a half of physics/math studies and decided to study art and translation, i’m not nearly as agile with math and physics as i was/would like to be. but i have some questions: so, we know that it takes force to accelerate a bike and rider. assume the same rider (because i can’t change that. in races, i always have to be me), but different bikes. bike A is heavy, bike B is light. bike A loses less velocity in the part(s) of the pedal stroke that don’t produce power, and also obviously gains less velocity in the power-producing phase(s). the opposite is true of bike B. but, though the changes in velocity are greater for bike B, the energy required to accelerate bike B is less, due to its lightness. so, assuming a flat course (which is a big assumption since no real-world course is truly flat) on which bike would i expend less energy? on A, with smaller changes in velocity, but greater energy required per mph increase in velocity, or on B, with greater changes in velocity, but less energy required per mph increase in velocity? (this obviously ignores important questions of physiology (lactic acid, NM fatigue, etc.) though those could probably be minimized by matching the gear combinations to the weight of the bike so the forces needed on each bike are equal.)
You have nicely summarized the delemma of this problem. I don’t know the answer, although I think it is amenable to a mathematical analysis. My suspicion is that for a flat, straight, course, the heavier bike will be found to be more energy efficient but I would not be surprised if I were wrong. I doubt it is of huge significance because the bike is a small part of the total bike rider combination, although, maybe riders will start to add weight to their bikes for these types of courses
Of more interest to me is the magnitude of the losses due to being a masher vs a smooth stroke. How important is it for riders to work on this aspect of their stroke? Again, this should be ammenable to mathematical analysis.
i agree that the stroke differences are more interesting since they’re things that can be changed during training. lance armstrong, from what he says, was a masher in his really early days and changed to a smooth stroke.
does anybody know of any studies on this published in journals?
I am quite sure nothing has been done in this area, although Mr. Not a rotorrooter seems to think everything has already been done in every area and there is nothing left to learn, at least not if the question is raised by some of us here. All you potential graduate students out there, heads up!
Frank,
Gary in SD and TTN will correct me if I’m wrong, but I believe the best 40K Time Trialists are for the most part mashers. Extremely big gears pushed by extremely big and powerful legs. I know I have heard this, and witnessed the mashing myself at local TT’s.
Yeah, that’s true, but I’d be willing to bet that, in some respect, they’re giving up quite a bit of their long-term efficiency for speed over the “shorter” distance of the time trial. A loose analog: a sprinter is in “high gear” in a 100m dash, but will not be able to hold their speed much beyond that. From what I’ve seen, time trialists are pretty well sacked at the end of the ride…not that I’ve seen everything…or a large, seriously competitive event.
On the topic of heavy versus light, I’m still waffling a bit, but I have a hard time reconciling the higher acceleration needed on the light bike with the increase in friction of the heavy bike. Of course, we’re really only talking at absolute most 8-10kg difference, so maybe I’m splitting hairs.
“Gary in SD and TTN will correct me if I’m wrong, but I believe the best 40K Time Trialists are for the most part mashers”
some of the best AMERICAN time trialists of the 80s and early 90s were mashers. but if you consider armstrong and hamilton america’s best time trialers, they’re riding pretty high cadences, 90-100rpms, and i think that’s pretty typical of non-americans as well who’re riding quickly in TTs.
as for the question of weight on a flat course, i hearken back to the race wheels of two manufacturers. not many remember this, but mavic made a disc some years ago in which you could put plugs that weighed the outside of the wheel in the hopes that on a flat course the extra weight would make the bike faster.
on the other hand there’s the nimble, which in its early days rested most or all of its technical claims on its “moment of inertia,” the idea being that you could accelerate it faster because of its lack of weight at the rim.
so (on the assumption that nimble believed its reasoning ought to have been followed for every course) here’s two companies who believed the entirely opposite things.
That may be true, but the only problem with the analysis is human nature. Everyone wants to win so everyone thinks the guy who won last time has the secret to winning so they all try to copy him/her. It may or may not be true that that person has the secret but soon they are all doing the same thing and so all the winners are doing the same thing.
It takes a lot of courage for someone to look for a better way because they may, actually, try a worse way. That is why modeling is so valuable, gives the person a sense as to whether something is worth trying.
Dan, I was looking at my USTS Hilton Head results from 1986 and looked at Scott Molina’s bike. He average 27mph for the 40K(eat your heart out Gary) on probably a slack angle road setup with the first edition Scott bars. What made him so fast and what would he have done with the technology we’re talking about in this and prior threads?
“What made him so fast and what would he have done with the technology we’re talking about in this and prior threads?”
what made him so fast was training, genetics and a brain. he was going just about as fast in 1985, before aero bars. it’s hard to speculate what he would’ve done with any of today’s technologies, but he’s another one that the world of bike racing allowed to get away. he’d have been a great bike racer.
