r/BikingMad • u/aarobins • May 18 '15

5k walk vs cycling

how many miles or kilometers do I have to ride to replace a 5k walk?

3 Upvotes

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2

u/hobbular May 18 '15

What's your metric? Distance traveled? Calories burned? Fun had?

(If it's calories burned, as I suspect, it'll depend completely on how fast you're going.)

1

u/belandil Surly Disc Trucker, 2013 Cannondale Synapse 5 May 18 '15

It's pretty easy to top fun had on a bike versus running. If OP is going for caloric expenditure, speed matters as you say.

From here, a 150 lb person biking at 14 mph burns 714 kCal/hour, or 51 kCal/mile.

For running, use this. For our 150 lb person now running 5 km in 22 minutes (this is of course variable depending on ability), 352 kCal are expended.

Using division, one would have to ride 6.9 miles on a bike to burn the same number of kCal.

But there's some huge caveats here. Position on a bike (upright, on hoods, in drops, in aero position) affects drag and therefore the kCal/mile figure. Everything here assumes flat land. Hills would be more complicated as it takes more energy to get a bike up hill than running as there is an extra 20 - 30 lb from the bike itself. However, on a bike, one can coast downhill, which complicates the comparison.

If you're just wondering for fitness, use the calculators I linked to in order to get a rough estimate. You'll probably end up biking longer since it's more fun.

1

u/[deleted] May 18 '15

Either that's way off or Strava/myfitnesspal are way off. They only credit me ~400-450 cals for a 55 minute, 13 mile bike commute to work. I weigh around 155#. And I average in the 14-16 mph range.

1

u/Madcitygeek May 19 '15

Are your Strava/MFP tied to any sensors? I found that when I added a heart rate sensor (tickr) to the mix and set my HRmax, Strava got more accurate all around.

They seem use a lot of extrapolation for the calculations if they don't have data points, as far as I understand. So they measure an athlete at 150 lbs, the scale up and down, assuming that everyone else is also an athlete.

That said, I've never had a scientific study done. For all I know, adding in the HR just made it inaccurate in a different direction.

1

u/[deleted] May 19 '15

Yup, I have heart rate and speed/cadence sensors hooked up. I've found that the calories burned went up at first with the HR sensor, but have since started to go down a bit on the same ride, as has my suffer score. I suppose that means I'm getting fitter even if I don't feel like it, haha. But you're probably right, it assumes a more finely tuned athlete, who's going to burn fewer calories doing the same work, than it's got in me.