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Comment by alexfoo | Hacker News Reader

Strava’s calorie estimation is awful.

Depends on the elevation gains in your 100km ride but I think that 3,300kcal for a 100km/4h ride is generous.

800kcal/hr is hard work and keeping that up for 4h is even harder. 25kph does not sound like 800kcal/hr unless there was some reasonable elevation gains. I’d expect at least 1000m elevation gain over that 100km for those numbers to at least approach something sensible. If it was a flatter ride than that then Strava is just lying to you.

But, yes, long distance cycling is an awesome way of burning calories. When I used to do Brevet/Audax riding I was the closest to my old teenage weight as I have been in the last ~30 years.

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Yeah, 25km/h requires less than 150W [1], so it's 600Wh total, the efficiency of human metabolism is about 20% [2], so it's 3kWh of total energy input = 10.8MJ = 2600 kcal. (I have been using generous estimates, so this should be an upper bound)

[1] https://en.wikipedia.org/wiki/Bicycle_performance#Total_powe..., https://www.road-bike.co.uk/articles/cycling-power.php [2] https://www.quora.com/How-efficient-is-the-human-body-at-con...

Given that we're talking about cycling, the solution is to buy a power meter and measure rather than estimate. Unfortunately that's a rather expensive option for all but the most committed cyclists.

Being someone who has a power meter, I can say that strava's estimates over a long time period aren't that terrible, but if you're riding in a group, or there was a some wind, or a million other reasons they can be absolutely miles out.

That's hardly strava's fault, it's more about what's actually possible with an estimate.

What is completely made up and should be ignored is the calorie burn estimates you get from gym equipment.

    Strava’s calorie estimation is awful.

Re-reading your post made me think: I bet this is intentional design -- overestimate number of calories burned. Then, people will tell their friends about this amazing device from Strava that burns an unreasonable number of calories...

I am also very skeptical of Strava's caloric estimates but:

> I’d expect at least 1000m elevation gain over that 100km

1% average grade is pretty mild. I'd bet OP did at least 3000m to get those numbers

It’s 2% average grade if you finish at the same elevation as you start.

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