There's been a flurry of attempts on the hour cycling record recently, with the latest attempt due later today in the village of London. It's generally considered to be a very pure measure of endurance riding since it's an attempt against the clock on a (usually) indoor velodrome. The only significant variables are therefore the fitness of the athlete and the air density. The latter is estimated to be worth up to a kilometre and so can certainly mean the difference between success and failure. This idea is simply to base the record on a "corrected" distance which accounts for differences from standard atmospheric conditions using a kind of equivalent airspeed. Further correction may be required to account for the partial pressure of oxygen and its affect on metabolic rate.-- EnochLives, Jun 07 2015 http://xkcd.com/852/ [pertinax, Jun 07 2015] ^ We would vote for that. All those irritating lycra-clad nurks lying strewn around in their silly trousers like a swarm of dead flies ... marvellous.-- 8th of 7, Jun 07 2015 Isn't the reduced drag from lower air density offset by the reduced partial pressure of O2?-- MaxwellBuchanan, Jun 07 2015 I did allude to that [MB] in the description, and I don't know which effect is more powerful. My main motivation for posting this idea was to get some opinions on this very point.-- EnochLives, Jun 07 2015 Obviously the entire velodrome needs to be depressurized, to perhaps 2.2 pounds per square inch of pure Oxygen (that converts to about 1kg per 645 sq. mm). It is barely possible for someone to climb Mt Everest without oxygen assistance; the partial pressure of oxygen there is about 2 pounds per square inch. So, add a little more oxygen, and remove all the rest of the stuff in the air, and THEN do your contest!-- Vernon, Jun 07 2015 //I did allude to that [MB]//
Ah, so you did - my apologies.-- MaxwellBuchanan, Jun 07 2015 Well he got the record (quite emphatically) but fell short of his own target, citing atmospheric pressure as the main reason.
If you assume that metabolic rate and drag both vary with air density then the effect of pressure cancels out. So either the sports scientists are wrong or I'm missing something important. It occurs to me that the drag coefficient will reduce as air pressure increases (higher Reynolds number), but this would have the opposite effect to that required. I don't get it.
[Vernon], I agree with your logic but not your numbers. At sea level the partial pressure of oxygen is about 3psi. On the top of Everest it's around 1psi. So 3psi of pure oxygen, or possibly a bit higher may be optimal.-- EnochLives, Jun 07 2015 I was going to mention differences in gravity depending on location, but [pertinax] beat me to it. I'm not sure if less gravity is better or worse...?-- neutrinos_shadow, Jun 07 2015 //If you assume that metabolic rate and drag both vary with air density then the effect of pressure cancels out.//
That statement makes no sense. If you assume that the effects of metabolic rate and drag are depend _equally_ and oppositely on air pressure, then it's true.
In any case, the effect on metabolic rate should be zero or negligible. At typical air pressures (or even at 50% normal pressure), blood leaving the lungs is close to 100% saturated with oxygen. Changing air pressure by even 10% will have no detectable impact on blood oxygen saturation. However, it would have a significant impact on air resistance.-- MaxwellBuchanan, Jun 07 2015 There should be a team of Sherpas from Nepal. They would totally kick butt in endurance races.-- RayfordSteele, Jun 07 2015 random, halfbakery