Monday, March 7, 2011

How badly do you want that donut?

By Brig Brandt, Peaks Coaching Group

Cyclists are known weight weenies, often spending thousands of dollars to save a pound or two off the bike. But how big is the weight penalty? What’s faster, a bike that’s two pounds lighter or a 10 watt increase in threshold power? Armed with a power meter, a steep climb, and twelve pounds of water I set out to answer some questions.

Before heading up my local (and much shorter) Alpe d’ Huez I weighed the total mass (me, bike, and clothing) I would be carrying up the hill both with and without the extra bottles. My two different weights were 184.5 pounds and 172.75 pounds. I climbed twice with each weight and I maintained (to the best of my ability) the same speed, letting wattage vary.

Obviously, because speed was maintained my times were nearly identical; approximately 5:15. However, the power output was very different: 346 average watts with the water, 311 watts without. So the 12 extra pounds required about 10% more power output.

How significant is that 30 watts? Like many things, it depends. If a rider can put out those 30 extra watts but has to exceed his threshold power to do so, then the increased power output will come at significant cost. However, if the rider can meet the increased power demand without exceeding threshold power, that is, without “burning a match,”  it will be of little cost (at least on a short climb).

A steep and sustained climb is the ideal environment to illustrate the power to weight concept, but not all (perhaps most) races have hilltop finishes. Nevertheless, for most of us losing a few extra pounds will pay big dividends in all race situations, because most races will include accelerations or climbs somewhere on the course. Getting over these climbs with less power means fewer matches burned for later in the race. If an athlete can lose weight without compromising power output then there will almost always be an increase in performance, regardless of the course profile.

Is there ever a trade off? If a rider keeps losing weight (and presumably some lean muscle mass, i.e. power) will he still climb faster? It simply depends on how much weight is lost and how much less powerful the cyclist is. An already lean cyclist should be very careful when trying to lose weight and should consult a nutritionist before embarking on any nutritional program. Underweight athletes are prone to long list of health problems.

There are three ways to improve your climbing: Increase threshold power, lose weight, or a combination of the two. Increasing threshold power is arguably the most effective method, as it will also translate into increased power on flat terrain and Time Trials. A rider who is carrying excess fat can also improve climbing by losing weight. However, a rider who is already lean will likely lose some lean muscle (and therefore power) if he tries to lose more weight, and this loss in power could trump the benefit of lost weight.

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