and it takes 1 calorie to heat 1g of water by 1°C, so with your daily recommended food intake of 2000kcal you could heat 2000l of water by 1°C or raise 20l of water from 0°C to 100°C.

Also a normal person can rides the bike between 0W and 100W comfortably, while trained people peak at around 1000W for short sprints.