We can use BMR (basal metabolic rate) as an ideal cycling weight calculator. BMR is the amount of calories your body needs in order to sit at rest and sustain itself daily, before you add daily activities. This equation can be very accurate in all but the very muscular (will underestimate calorie needs) and those with a very high body fat percentage (will over-estimate calorie needs). Also note that individual metabolisms can vary within a range of 20%. This formula can get you in a good ball park for your caloric needs and generally works quite well. As you put your calculation into practice you can make small adjustments as needed if you find you have a high metabolism and seem to require a bit more calories than the calculation states, or vice versa.