I have done a couple of 6 hr and a 24hr and I can say it depends on the terrain. They can be tiring to ride because of the stump pulling power. However, anti-vibe bars like Fasst flex or twisted engineering help out a ton with anti-vibe bar ends make a huge difference. A balanced crank is a great investment too. Lots of seat time will also help you know how to manage the power. I found using a higher gear an using the clutch less reduced fatigue on the left arm and hand. I have a big fuel tank and could plan on 70 miles unless there was a lot of wide open running. Every riding style results in a different mileage result. Seat time will give you an idea. Spend lots of time on a rowing machine and do about 10,000 push ups! Good luck!!!
