Notes from the Green Party Candidate for South Norfolk, for General Election 2015. Longer reflections and discussions on issues relating to policy, the good life, justice, equality, anti-austerity economics and the future of the planet. This is also a forum for exchanging ideas on how to tread lightly on the planet and avoid supporting exploitation and corrupt practices. Here we go...

Tuesday, 29 May 2007

Cycling and energy

There's a long running dispute in our household as to whether it uses more energy to cycle fast than to cycle more slowly.

I don't mean does it take more energy for the same amount of time. Obviously cycling faster is harder work, and uses more energy in a short time.

The question is this: if you need to go from here to the Sidgwick site, and you could go gently at, say, 10 miles an hour, or very energetically at about 15 miles an hour, you'd get there quicker by the latter method, but would you have burnt up all your weetabix more effectively?

Well here's the answer. Suppose the Sidgwick site is 2 miles away. Going at 10 miles an hour it will take you 12 minutes. Going at 15 miles an hour it will take you 8 minutes.

If you weigh 10 stone (which I don't, but never mind: we're trying to compare the results for the same person, not different people), riding at 10 miles an hour uses about 381 calories an hour, so you'll use 76.2 calories in 12 minutes.

The same 10 stone individual riding at 15 miles an hour uses about 636 calories an hour. So you'll use 84.8 calories in 8 minutes.

A serving of two weetabix with milk provides 190 calories, so by riding to the Sidgwick site you'll have used less than half your calories either way. But the difference between riding fast and riding slowly is 8.6 calories, which is about 1/10th of a weetabix. So if you are going to ride energetically, you'll need to eat a bit more breakfast if you're not to get hungry before elevenses (but on the other hand you gain an extra 4 minutes in which to go to the Buttery and get a coffee and a doughnut to keep you going).
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