28 January 2011 ~ Comments Off on Why Tall Cyclists (like me) Suck On Climbs

Why Tall Cyclists (like me) Suck On Climbs

This confirms why sometimes I get blown away on the climbs by cyclists, usually much shorter than I (I’m 6-4). This all has to do with the fabled power to weight ratio (or strength to weight ratio) for those of us that participate in anti-gravity endurance sports like trail running, mountaineering, cycling and backcountry (rando) skiing.
I just reviewed the 2010 photos of the solo winners of a tough 500+ mile race in Utah, called the HooDoo 500 (thinking of entering it this year). Sure enough, the winner (by a landslide) was a short, little thin guy.
From the 1/2/7/2011 issue of RoadBikeRider.com

2. COACH FRED

Why Can’t Climbers Go Faster on the Flats?

Q:  Why is there such a separation between riders who can climb well and those who are strong in time trials or other flat races? I don’t understand why most strong climbers can’t go fast on level roads, or why powerful sprinters suffer so much in the mountains. — Barry M.

Coach Fred Matheny Replies:  It’s simple mathematics, Barry. The answer involves body weight, power output and wind resistance.

On flat roads, speed is primarily restricted by the wind resistance created by the front of a rider’s bike and body.

Big riders in a low racing position don’t have a frontal area drastically different from that of smaller riders. But big riders do tend to generate more power thanks to their larger muscle mass. That’s why time trials and sprints — typically on flat or rolling terrain — generally favor rangy, muscular riders.

However, as soon as the road tilts up, the advantage shifts to smaller cyclists, even if they produce less power.

A rider must fight gravity when going uphill, so climbing requires a favorable power-to-weight ratio. The more watts a rider can produce for his (or her) body weight, the faster that rider can climb.

So here’s the bottom line: To improve climbing, you must either lose weight, increase your sustainable wattage — or do both.

This power-to-weight ratio is so indicative of climbing prowess that some coaches claim they can use it to predict a rider’s success.

They measure the average wattage a rider can produce for the length of a long climb (say, 20 minutes) and divide that figure by his weight in kilograms.

So, a big pro who weighs 85 kg (187 lbs.) and can produce 425 watts for 20 minutes has a power-to-weight ratio of 5.0. (One kilogram equals 2.2 pounds.) But top climbers have a ratio of 6-7 watts-per-kilo.

For comparison, a 60-kg climber (132 lbs.) needs to produce only 360 watts to achieve 6 watts per kilo. But since this diminutive climber pushes almost as much air when riding on the flats as the larger rider, he’ll time trial slower because he produces 65 fewer watts.

(Copyright, used w/o permission)

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