Google Calculator Almost Delivers
February 10, 2007
Tonight I rode the Lifecycle for 44 miles in 2 hours with a cadence around 96. Lifecycles do not report any estimate of average watts, but while grumbling over this fact, I realized that calories per hour is also a measure of power. Awesome! So after my workout I figured I’d rush home and type in “875 Calories per hour in watts” into Google Calculator, and viola, I would have my average watts…
875 (kilocalories per hour) = 1016.94444 watts
Hmmm… Yep, I averaged over 1000 watts for 2 hours straight. Ha! So I guess, my initial theory was a little whack. Clearly there’s a difference between the power I generate while riding the bike (Calories burned per hour), and the power that’s actually transferred to the pedals (what I mean when I say “watts”).
Oh well, it was a good thought.
Digressing further… assuming the numbers above are accurate, and assuming the actual power transferred to the pedals was somewhere between 200 and 300 watts, then isn’t that saying that I’m only about 20-30% efficient as an engine for a bike. That’s kind of interesting. Huh.
February 21, 2007 at 2:11 am
According to Allen Lim at the Floyd Camp, it’s 1.1 kc per wheel watt, because the body is 1/4 or so efficient in converting food calories to mechanical enegery. So 845 cal/hr is about 211 watts average, which also agrees with the lifecycle I use at work, and the powertap on my bike’s count of kilo-Joules, being delivered watt/seconds.
TBV
February 21, 2007 at 9:10 am
Awesome! That is very helpful.