I am a 40 year old reasonably athletic male, who hasn't ridden other than leisure rides for many years. In the past year I got back into riding, for fun and as an alernative exercise to running due to herniated discs.
For the past few months I've been riding between 6 and twelve miles almost every day, other than inclement weather. On weekends I have done 20-30 in a day without too much fatigue.
Should I ride every day, or do I need a rest period like in weight training? What are a few basics I need to focus on to improve my fitness? Distance? Cadence? Harder shorter rides or longer ones with less speed/muscle effort? Is there a good resource you could direct me to with the basics of cycling for fitness? I'm not training for triathalons or any event (yet!), but just want to become a stronger rider and drop a few lbs. along the way.
BTW, I've mostly been riding a fixed gear bike with 70 gear inches, which is pretty easy for me to spin other than up steep hills. I have a geared bike, but really enjoy the feeling of riding fixed.