Larger riders have unfair advantage in power to weight?

Discussion in 'Power Training' started by wilmar13, May 15, 2006.

  1. wilmar13

    wilmar13 New Member

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    I was thinking about something the other day that should give larger an advantage in climbing (although anecdotally it doesn’t since smaller guys seem to be on avg better climbers)… when you consider that the UCI weight limit of 6.8 Kg is universal wouldn’t a 50Kg guy who climbs at 200 watts be at a disadvantage to a 80kg guy who climbs at 320watts? I mean the P/W ratio is the same for the riders, but the rider-bike combination is better for the larger guy… about 5% actually…(320/86.8 vs 200/56.8). No one really talks about P/W bike-rider combo, but isn’t that really a better measure than just power to weight?
     
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  2. 11ring

    11ring New Member

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    Yes. And the bigger rider will have a much higher drag to wind resistance ratio too. The UCI limit is unfair to smaller riders. They could ride lighter bikes as they dont break stuff as easily, but can't due to the weight limit.

    Point is, lighter riders tend to and have to (to win) have higher power to weight ratios. P to weight is actually not a good measure of performance.

    power ^ 1.xx / rider+bike weight is better. The xx should be positive, and depends on the course.



     
  3. wilmar13

    wilmar13 New Member

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    Keep in mind I was focused solely on climbing… as you eluded to larger riders (speaking from experience) have a real disadvantage in most road race/crit situations… we do not receive the benefits of drafting as well as everyone else. I am so glad when I can find the wheel of someone equal to my size… so often I am sitting on the wheel of some 5’6” guy getting little reprieve from the wind while he in turn sits on my wheel like he is motorpacing. :mad: Of course that doesn’t seem to bother the big men of the peloton that can or could sprint well after a leadout: Boonen, Cipolini, Backstedt, Hincapie, etc. Anyway my point was that in climbing larger riders (with equal P/W ratios) should have an advantage, but the results seem to suggest otherwise.
     
  4. 11ring

    11ring New Member

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    They dont have the same power to weight ratio's.

    If a 90kg + rider had the same power to weight as a Pantani or Heras they would win every race they entered in. And TT at a phenomenal pace. Like 55+ km hour average.

    They would have to have a LT power of 600 or 700 watts to get the same P/W as these riders.

    Why they cant get that high is an interesting question. A lot of it is to do with the fact that lungs and hearts don't increase in size proportional to increases in weight. Usually they are heavy becuase they are muscular sprinters. In this case the extra weight makes them fast over short distances but is of little use pushing them up long hills.



     
  5. wilmar13

    wilmar13 New Member

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    There are a ton of variables here, but I was assuming that proportionality remained constant so that we aren’t talking about ectomorph/mesomorph body types(i.e. heavier = taller rather than blockier)… I agree, you do have a point that larger riders probably don’t have the P/W ratios of smaller riders… Indurain was a larger rider (80-82Kg) that was exactly what you described, TT’ed like hell, dieseled up the climbs, and not much else, but it was enough to dominate stage racing. It would be interesting to compare his P/W ratio to the smallest dominant rider of any era (he is the largest dominant cyclist?).
     
  6. RapDaddyo

    RapDaddyo Active Member

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    Actually, I think the charts and analytical programs that are based on P/W ratio do use the rider + bike weight (if you read the definitions carefully). I know that analyticcycling's tools use total weight and I think Andy Coggan's comparative tables use total weight. But, you're right that many lapse into using simply rider weight. I would guess that the FTP poll is based on rider weight only, which no big deal but it means the data aren't comparable to Andy's tables.

    Edit: Curiously, I could find no reference for the w/kg numbers in Andy's power profiling spreadsheet. This is unlike Andy to not define a data element more precisely, but I'm guessing his numbers are in fact power to total weight (rider + bike) ratios.
     
  7. acoggan

    acoggan Member

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    No, it's the mass of the rider alone, since physiology doesn't know or care what a bike weighs. IOW, the reason that the data are expressed relative to mass is simply to take into consideration differences in body size*, not because W/kg is a predictor of performance (esp. uphill).

    *There are theoretical reasons to favor an even more complicated expression, e.g., W/kg^2/3. However, I haven't gone down that road for two reasons: 1) the use of such allometric scaling isn't automatically correct, and needs to be confirmed via large-scale studies, and 2) many people have a hard time wrapping their mind around a fractional exponent.
     
  8. bikeguy

    bikeguy New Member

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    Yawn. M^2/3. It's the cube root of the square of M.

    -Bikeguy
     
  9. frenchyge

    frenchyge New Member

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    I found the ^ button on my calculator, but where's the 2/3 button?? :p
     
  10. RickF

    RickF New Member

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    (2/3)
     
  11. robkit

    robkit New Member

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    i think that power:weight of rider + bike ratio is more relevant, it also in some small way reflects the efforts you can make from your wallet as much as the physical ones.

    one thing that got me thinking recently..shoes. i changed my old Carnacs for some very light DMT's, saving almost 400 grams (~ a pound) in total. is that weight of rider or weight of bike? ...doesnt matter if you count everything.
    it also occured to me...i was turning that weight around 90 times a minute....got to be costly?
     
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