I seem to have hit a plateau in terms of my cycling performance. I can't go as hard or as long on these group rides. I thought it was just me not riding enough but when one of my friends bought a new bike, never having cycled before other than putzing around, and was able to out last me and perform better, it got me thinking.

I'm only 5'4' and that means a smaller bike frame and shorter legs. Also I would consider lung capacity to be smaller too if that matters... Anyways, how much does height matter in cycling? Can I ever be as good as a 6' dude if we train the same?