I did 2 centuries and a metric on my 7.5 this year. I did the Montauk and the North Fork which are both very flat. Finished both in under eight hours total and about 7 in the saddle. The metric I finished with a 16.5 mph average speed. On each ride I passed a bunch of people on much fancier lighter bikes than mine. It never even crossed my mind that you couldn't do it and I plan on doing a lot more in the future even though I'm kinda old and out of shape.