For most cyclists, a good rule of thumb is to aim for 30-90g of carbs/hour if you’re exercising for more than 90 minutes, which equates to 120kcal - 360kcal/ hour. If you’re riding anywhere from 2-6 hours/day for 5-6 days/week, you may expend roughly 600-1200 kcalories (kcal)/hour on the bike so eating during your ride, and after your session is important for avoiding muscle loss, repleting glycogen stores and accelerating recovery . Daily calories needs for cyclists can vary from 2,000-7,000 kcal/day (or more), depending on body weight, age, sex, and training load.
 Kerksick, C.M., Wilborn, C.D., Roberts, M.D. et al. ISSN exercise & sports nutrition review update: research & recommendations. J Int Soc Sports Nutr 15, 38 (2018). https://doi.org/10.1186/s12970-018-0242-y