Comment by Jenda_

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...