I'm a 52 year-old male, 5 foot 6 inches tall, weighing between 155 and 160 pounds. After about 20 years as an active avocational runner (I would average 50-60 miles a week; I also did five sub-4 hour marathons during that period) I took up cycling about 13 months ago, and I've gotten into it fairly heavily. In fact, I haven't been doing any running since I started cycling. Currently, I ride about 350 miles a week; my speed ranges from 16.5mph to 18.5mph.

Whereas a daily calorie intake of 2800 seemed to support my running training pretty well, it feels inadequate for the amount of cycling I'm doing. I've been trying to eat enough to make sure I feel strong, but I find myself significantly more hungry as a serious avocational cyclist than I did as a serious avocational runner. As I feed this appetite, I worry that I am in fact over-eating; I'm not overweight, and my performance on the bike continues to improve, but I'm not particularly slim either, and the whole eating aspect of this process feels a bit random and undisciplined.

So I'm wondering if anyone can point me to information or resources that might provide some calorie intake guidelines for a rider my age who is doing the amount and type of riding I've described above. Thanks in advance.