I just started riding, and on most of my solo rides I average 16 or 17 mph over rolling terrain with mild wind (10-15 mph). I'm 5' 10" 140 lbs. The thing is, I am usually never above 21 mph on the flat roads. Even when I'm just starting the ride and my legs are fresh, I just can't get very much speed. But at the speed I DO ride, I never really get winded. Meaning, I'm never huffing and puffing. So the problem is not my heart. My quads hurt though.
Now I know there is a difference between muscular endurance and muscular strength. For endurance athletes like cyclists, muscle endurance is very important. But if I can never even get to a high speed, is my STRENGTH (vs. muscle endurance) limiting me? If so, will strength increase when you ride every day, or do you really only gain strength in the off-season?
I'm asking because I want to increase my average power output on my rides. But I'm not sure if my leg endurance or leg strength is limiting me. It is definitely not my heart. Following bodybuilding principles, working a muscle group every day doesn't give it sufficient recovery time to grow. So how can I gain strength while riding every day? And is that most likely what I need to build on to get better (leg strength)?