Longest i ever rode and kept track was 34 miles. It was maybe the first month or so that I'd had a bike. Weeks later my knee swelled up. I'm not entirely sure if they were connected as there was time in between. I was entirely not conditioned and didn't stretch so. Those number of miles are certainly doable by many riders here. It should be mentioned i was on a hybrid going at a leisurely pace stopping maybe evry half hour, had lunch and checked out stuff along the way. Took about 5 hours. 10mph should be a fairly leisurely pace not including stops.