Let's try to troubleshoot:
[list=1][*]Does it only happen when you ride in the evening?[*]What happens if you ride during the day?[*]Does it happen only when you cycle? What about other types of workouts?[*]What is your fitness level?[*]Did you consult your doctor before staring this exercise program?[*]Do you eat before you ride?[/list=1]
I've never heard of anything like this that is cycle related. Anybody else experience this problem?