3 ms·
Actually, on a flat surface with a constant speed or acceleration, weight matters much, much less than frontal area. Weight comes into play much more when many
by irl_zebra 11y ago
Actually, on a flat surface with a constant speed or acceleration, weight matters much, much less than frontal area. Weight comes into play much more when many quick accelerations or elevation gains come into play.
Because frontal area doesn't increase proportionally with weight, I would argue that power output should be the primary concern and that typically increases substantially with weight. For evidence of this, look at world class time trialists versus world class hill specialists.
Fabian Cancellara [1] is considered one of the top time trialists in the world at 181 lbs as he can put out much more absolute consistent power than someone like Nairo Quintana who is considered one of the world class climbers and weighs 128 lbs, [2] even though Nairo Quintana may have a better power:weight ratio.
[1] https://en.wikipedia.org/wiki/Fabian_Cancellara https://en.wikipedia.org/wiki/Fabian_Cancellara
[2] https://en.wikipedia.org/wiki/Nairo_Quintana https://en.wikipedia.org/wiki/Nairo_Quintana
- QuotedForTruth 11y agoTrack sprinters are even bigger, further showing your point. Chris Hoy is 205 lbs.
- davidw 11y agoExactly. https://en.wikipedia.org/wiki/Tony_Martin_(cyclist) https://en.wikipedia.org/wiki/Tony_Martin_(cyclist) weighs in at 75 kg - lighter than Cancellara - but not that light for a professional cyclist either.
- mxfh 11y agoWas wondering the same since, this is about top speed and not about acceleration the weight shouldn't matter much at all, since it has no direct influence on the air resistance. Would be interested in knowing, if a human powered vehicle on steel rails with steel wheels with the same air resistance could be faster than this just due to the lower rolling resistance.
- mapt 11y agoYou've got it reversed. Weight shouldn't have as much of an impact on acceleration because as muscle mass & power goes up, weight goes up as well. But more weight inside the shell doesn't increase air resistance, while it does increase power. So a heavier rider with greater sustained power output will, in an environment where wheel friction is trivial, go to a considerably faster top speed on flat ground.
- mxfh 11y agoDid anything happen to F = m × a in the last 20 years? Acceleration a is heavily dependent on the mass m. Since a = F / m having half the mass would result in double the acceleration with same amount of force F available.
- thedufer 11y agoUnlike in high school physics, we have to account for drag, which is a lot more important than mass at these speeds. F=ma is true, of course, but you have to think more about what F really is.
- mapt 11y agoThe same amount of force F is not available. If they're putting athletes into this thing, the bigger the athlete, the more force (okay, the more power) is available for propulsion. They have bigger muscles which store more glycogen and have greater total mitochondrial activity, because there are simply more of these cells available to do the work.