Thursday, November 19, 2009

Calculating Cycling Power Output


Harjinder here. Since this is a notice board for our club, here goes:

1. My "cycling" weight is ~94kg (don't larf)
2. My bike weighs ~10kg
3. The height of the HHC011 hill climb is ~65m (from the fab map site: www.bikehike.co.uk)
4. It took me 173 seconds to climb it

Therefore, my average power output during the climb (P) was:

P = mgh / t = [(94+10) x 9.8 x 65] / 173 = 382 W

Now, turning this round, the time for the climb, t, is given by:

t = mgh / P

If I was to lose 5 kg (not unrealistic if it wasn't for Christmas, pudding, cake, mince pies, er...self control, etc) while keeping the same power output, then:

t = [(89+10) x 9.8 x 65] / 382 = 165 s

that is, a saving of 8 s.

Conclusion: Pah! Losing 5kg would only save me ~8 s. So, stuff it, I'm gonna enjoy my food over Christmas! Or to look at it another way, I could put on 1kg, buy a bike that is 1kg lighter, and have a heart attack on the climb next year to get the same time.... hmmm.... Take a look at the guy below and compare with Mr Grimes above. Now, who looks happier, eh?

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