I see "big kids" on 20"ers and LMAO.
Several of them have thought it would be easy to waste this old man in bicycle sprints.
Now they know better.
Straddling a traditional road bike, you should just have enough room to clear the jewels. For best pedalling efficiency the leg should be nearly but not all the way straight at the knee when the crank is furthest down. Seat too low and you WILL tire earlier.
It seems silly to say it, but
proper pedalling is hard (mentally) and requires constant vigilance. That is, in the best case scenario you do NOT want any dead weight from the leg on the upward swing working against your "power" leg on the downstroke. Of course I am talking no toe clips. Concentrating on lifting that upstroke leg gives you something to do!