On my weekly club rides I am certainly not one of the fast riders. I always joke that I belong to the "reasonably" fast group. Yesterday was the 1st time I was able to hang with the fast riders for a good while. I manged just over 10 miles. We were cranking steady at 24 mph on flat ground. I was riding the whole while right at my aerobic threshold. Around the 11 mile I finally ran out of steam and could not maintain the speed. I rode slowly for a mile of so to catch my breath and let me legs and body cool a bit. A few miles down the road I saw the medium/high speed group coming up. I jointed them and rode the remainder of the 30 mile ride at 21 to 22 mph. For me that is about as fast as I can go in a group for an extended period of time. Even through I could only hang for about 1/3 the ride, that is still much better than last year. My legs and lungs are getting stronger. Now I need to start working the core, that should help a lot.