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Alex Dowsett recently set a new world hour record of 52.937 kilometres, how much power did he have to produce for an hour to be able to achieve this feat?

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  • 1
    If you have Twitter, this is the guy to ask: twitter.com/xavierdisley We can only guess, while he has some experience in getting the actual data.
    – Slovakov
    May 4 '15 at 8:59
  • World UCI Hour record. The actual human powered hour record is kept by the IHPVA, and is significantly further.
    – Móż
    Aug 21 '15 at 7:55
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We cannot know exactly unless Dowsett's team releases it, but we can make a reasonable estimate. The most important unknown is Dowsett's drag area, or CdA, so below I have calculated the power needed to average 52.937 km/h for various values of CdA, given the assumptions noted on the figure. Notably, rho is air density in the velodrome and a trackside observer provided the estimate of 1.16 kg/m^3; Dowsett is listed as 75 kg for his "official" weight so 85 kg is an estimate of the rider plus bike plus shoes plus helmet plus suit; eta is drive train efficiency and for fixed gear bikes with a good chainline losses tend to be around 2.5%; and the coefficient of rolling resistance for track tires on a smooth wooden velodrome surface will be in the range of .0025 to .003. Thus, if Dowsett's drag area were around 0.195 m^2, his average power would have had to have been about 400 watts.

estimated power for CdA for Dowsett's hour record

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According to Canyon, it would be approximately 400 watts average. Since an hour record attempt requires that there be no computer on the bike to be official, a more accurate measurement is unlikely to be available.

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  • The article you link mentions a power meter that is integrated in the crankset, which contradicts your argument. Could it be that the rules only state that the bike is not allowed to have a computer which shows any values to the rider, i.e. the rider is not allowed to know their speed during the ride. May 4 '15 at 14:29
  • 1
    You're not allowed to use a computer for pacing, but you can record and look at it after the fact. I read this looking for answer to this question, but I can't find the article anymore.
    – alex
    May 5 '15 at 3:35
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    A power meter was mounted on the bicycle but according to UCI rules no visible display is allowed so the data are either for review post-ride or can be transmitted to a track side computer for real-time analysis.
    – R. Chung
    May 5 '15 at 5:51
  • Can the team shout out average speed as he rides past or is the rider allowed no information?
    – Holloway
    May 5 '15 at 12:12
  • The rider is allowed to receive very limited information, according to UCI rules: pace, distance covered, or time. If the velodrome is quiet you can shout out lap times but generally for record attempts you use a chalkboard -- though of course more recently teams have been using iPads or other tablets. You don't want to give the rider too much distracting information.
    – R. Chung
    May 5 '15 at 13:26

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