Originally Posted by
pdlamb
This.
Crank as hard as you can, as long as you can, and it'll take a toll on your body such that you need to cut back or even take a day off. Ride moderately, and you may need a "recovery ride" but you can still ride. Build up, and you'll get to the point you can commute 10 miles each way (20 mile round trip) all week, and still enjoy a couple longer weekend rides.
This.
If you ride slow and easy, you can do it all day every day and barely feel it.
If you ride as hard as you can possibly push it for even and hour every day without taking a break...your legs might fall off.