I only had one cycling goal for this year, and that was to break 16 mph for an average speed over a non-trivial length ride (basically 10+ miles over flat terrain). Last year I hit 15.9 a few times, but couldn't get over that. I managed that speed a few times this year too, but still couldn't break 16. Finally, a few weeks ago I did it. I said to myself, "today, you're going to break 16 mph." I did 10 miles that day at 16.8 mph. That's a full .9 mph over my previous record. Damn good.
Recently I've been riding with a group of pretty fast people, some of whom have done (and won) cat 5 races, and who usually go with the 17/18+ mph groups with the cycle club. I've been going along with a "recovery" ride, which is supposed to be easy spinning under 15 mph. It's not always so easy, certainly not for me anyway. Sometimes a speed interval shows up, or some hill climbing comes into play. A few times I've fallen behind, but they're not too bad. Either way, I know riding with them has helped me some, and I've also been trying to do some hill and speed intervals on my own.
During some of my speed interval rides I was in the 16.7-16.9 mph range on the average for the ride, which is about 25 miles long. I'd do the intervals on the way out, usually getting up to about 22-24 mph for one minute, then resting for four minutes at 13-15 mph. When I was done, however, I'd be cruising along on the ride back to the start at roughly 18-19 mph. That's been relatively consistent, and it's a flat trail too, so there's no advantage to the return versus outbound trip.
Today, I went out to do that same route, although I wasn't in the mood for speed intervals. I just said to myself, "today, you're going to break 17 mph." To get right to the point, I averaged 17.8 mph for the whole 25 miles. 😄
I've only been riding seriously for about 2 years now (or semi-seriously depending on who you ask, as I only have about 1,300 miles for this year). I floundered along the first year, usually sticking around the 14 mph range, and not seeing much physical difference in my self or my riding abilities. Since July of this year, however, I've lost 15 pounds and I can definitely feel the muscles in my calfs. I still have a long way to go, I weigh 260 now, which is still too high, but it's at least going in the right direction. If I could continue to add 1 mph every 6 weeks to my max speed, I'd be all set, but I'm not going to hold my breath. 😉