Training & Nutrition - "trimming 1 lb saves you about 2 watts"

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zowie
08-19-09, 10:43 AM
TYPO IN THREAD TITLE: should be 3watts

An article in that respected journal, Bicycling, titled "The Smallest Loser" ...
http://www.bicycling.com/article/0,6610,s1-4-21-20014-1,00.html ... says: "trimming one pound saves you about three watts".

I've never heard anything like this before and it doesn't seem right. Losing 20 lbs saves you 60 watts? Maybe if you only weigh 120 pounds and put out 400w, which is hardly anyone.

gregf83
08-19-09, 12:13 PM
I think it's a typo or the author got confused. Losing 1Kg will save about 3W on a hillclimb.

thump55
08-19-09, 12:35 PM
I don't think you can just multiply them both by 20. The author was focusing on cyclists very close to their ideal weight.

gregf83
08-19-09, 12:47 PM
I don't think you can just multiply them both by 20. The author was focusing on cyclists very close to their ideal weight.It doesn't matter how you slice it, saving one pound of bike or body weight will not yield the same gains as an extra 3W of power. You can confirm this for yourself on any of the readily available bike power calculators.

Carbonfiberboy
08-19-09, 01:03 PM
There seems to be a difference of opinion on this. If you use the online power calculators, on a 6% grade, one pound loss = 1 watt saved . . . about, depending on rider weight, etc. On an 18% grade, it's about 2 watts saved/pound lost. If you believe that, you're much better off focusing on maximizing your power at LT than on weight loss, if you're anywhere in the weight ballpark. However, if you've maxed your power, then weight loss is the only thing that helps.

OTOH, Carmichael estimated that Lance saved about 1 minute/kg lost on the Arcalis climb, stage 7. The bike calculators give a result of about half of that. My experience is that it's closer to Carmichael's estimate, though I don't have power figures to base that on. It just feels like body weight loss makes more than a 1w/lb. difference. But maybe there's more to it than just weight, like it was lead or something. Maybe the leaner body is more efficient, especially out of the saddle, and maybe a leaner body is also more aerobically efficient.

Pretty hard to study this, because losing body weight will probably affect power output and endurance, so lots of loose variables.

I believe the online calculators are correct as regards the watts saved by losing bike weight. I'm just not so sure about body weight.

Dubbayoo
08-19-09, 06:19 PM
Salesman approaches a farmer and says "I have a machine that will cut your work by 50%. are you interested?". The farmer says "50% each?? I'll take TWO"