I don't lift weights anymore. Did in the past when I was a teen and early 20s. In my 40s now, don't lift, ride 100 to 150 miles a week, oh, and I don't have a hamstring muscle in my right leg and I'm still faster than some guys who have both hamstrings, lift weights, and ride a lot. When I ride alone I focus on intervals, and have a very high pain threshold. I'm 5'9" and weigh 145 to 150lbs. I would think that some moderate weight lifting to increase strength certainly would not hurt, but it's really about training/riding, cadence, increasing endurance, focusing on breathing. In a nutshell - smart training. Having said that, some people just have more natural ability than others. That's just something that is humbling and has to be sucked up.