I rode 60 miles today, which is the farthest I've ridden in a very long time. I ride single-speed, and my previous max was about 40 miles, but I recently upgraded my wheeelset and the new wheels have Phil Wood hubs which roll so much better than my bike's stock wheelset . . . so I extended it today to 60.
I know the roads well enough, but didn't realize the extra distance took me down a road that included almost a mile of BRICK, which was slippery in the rain. Otherwise the only concern was riding into a stiff headwind on the return, which is always a bear on a single-speed bike.