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Tip of the Week -- Dissecting Power Numbers

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Tip of the Week -- Dissecting Power Numbers

Postby natellerandi » Sat Apr 06, 2013 12:47 pm

I read a really interesting article the other day. The premise is that when looking at a cyclist's ability to climb, it goes beyond the simple power/weight ratio (watts per kilogram, or w/kg). What appears to give a more accurate assessment of climbing capabilities is w/kg to the power of 0.79 gives a better correlation between power, rider mass and performance.

And this makes sense. Typically, climbing prowess is explained by a rider's power-to-weight ratio. However, tweaking the ratio as mentioned above is the key to better understanding perfomances. Afterall, factors such as gradient, steadiness of the pitch, length of climb, etc. all play factors on who is the strongest climbing on the road.

As roads get steeper, explosive climbers benefit from their lighter weights while the larger riders are forced to stick to a steady tempo. Accelerating that extra mass becomes problematic because it costs them more in terms of power, stress, lactate production and rising HRs. The reason is that the steeper the gradient, the higher the proportion of power output that gets put toward fighting gravity. The heavier you are, the more you have to fight the effects of gravity rather than propelling yourself up the climb. This is identical to the challenge in swimming -- buoyancy vs propulsion. Which is why poor swimmers derive greater benefits from wetsuits than fast swimmer.

What I take from this article is that it really isn't as simple as labeling yourself as strong "on the flats" or "on the climbs". The big guys on my cycling team can hold my wheel and have a cup of tea on the shallower gradients of a climb. It is in the medium pitches -- 6-12% -- where I tend to drop guys. Yet, smaller and more lithe climbers will drop me in the steepest of pitches. This is also why I struggle on the flats in crosswinds compared to larger riders -- more of my energy is spent combatting the effects of the wind rather than propelling myself down the road. Guys who I can out-TT and who I can ride off my wheel on a calm day can bring me to my knees in a crosswind or headwind scenario.

It's not just about power output and w/kg ratios. There are numbers behind the numbers which tell the complete story and can really help you better identify the types of courses you naturally gravitate toward and could target in order to make your racing experiences as positive and enjoyable as possible.

Happy Training,
Nate Llerandi
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Re: Tip of the Week -- Dissecting Power Numbers

Postby mattkuch » Tue Apr 09, 2013 2:13 pm

Very interesting read-thanks for posting Nate.
This makes a lot of sense to me, as a rider that is bigger than the light and spry riders, but smaller than the clydesdales. (about 175lbs)
thanks!
Matt
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