CCM Diary: Bike Hangover

I didn’t get much sleep last night.  When I went to bed, my legs started to hurt if I left them in one place for a little while. It wasn’t a lot of pain, mostly an ache in my quads.  I’d move my legs and the feeling would go away, and then in a minute or two it would come back.  Finally I got up and went downstairs to read until exhaustion overcame discomfort.  This morning I felt like I had a bad hangover, which isn’t fair if I don’t get the night of drinking first.

My quads still feel a little off, though today’s bike ride went OK.  Of course, that’s why I bike – to give my running muscles a break while still getting some exercise.

I’ve had this problem before, but usually after something a lot more strenuous than 20 miles at long run pace, no matter how hilly it was.  Maybe I’m just getting old, or maybe I’ve been overdoing it lately and I haven’t let myself recover completely.  I’ll know more after track on Wednesday.

While I was riding, I got to wondering about how rider weight affects bike speed.  It’s not as simple as “more weight is bad”.  I’m a small guy, and I’ve watched too many bigger people pulling away from me on downhill grades to accept that without question.

Extra weight definitely holds you back when you’re going uphill.  A 2003 Bicycling Magazine article says that on a 5 kilometer, 7% grade, every 5 pounds added make the trip up the hill take 30 seconds longer. So a 160 pound rider will take 19 minutes and 21 seconds to get up the hill and a 220 pound rider would come in 6 minutes, 10 seconds later.  But they don’t provide any data about the advantage a heavy rider gets from gravity when he’s going downhill.

On the flats, weight doesn’t matter as much.  It’s not like running, where my legs have to hold my weight up in addition to propelling me forward.  On wheels, the only cost of extra body weight is a little extra friction at the wheel hubs.  A Wikipedia article says, “lowering weight by 1 lb will have the same effect over a 40 km time trial on flat ground as removing a protrusion into the air the size of a pencil.”

A heavier rider also has to expend extra energy because he has to overcome more inertia when he accelerates.  That’s partially balanced by the fact that extra weight, properly applied, can help a heavier rider apply more pressure to the pedals on the downward stroke.

Some people say the fact that top bike racers are lean proves that less weight helps you go faster.  But if that were all that mattered, bike riding would be dominated by tiny people, and it’s not.  More bulk, when it’s in the form of muscle, helps a rider generate more power to go faster. In reality, top racers are lean because you can’t ride enough to be a top rider without burning off any excess weight.

I didn’t find data that summarizes all this but if I had to guess, all else being equal, it’s probably better to weigh less.  But all else is never equal.  That’s why riders say when discussing the value of shaving weight from the bike itself, “it’s not the bike, it’s the engine”.

(16.7 mi. bike; 145.5#)

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