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?

  • 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

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


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.

  • 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
  • 2
    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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