It's like anything, you just need to practice and build up to it. If you go out day 1 and try to ride 800km you're going to have a bad time. Being physically fit also helps a lot imo. The r1100r also doesn't have much in the way of wind protection which is tiring. An 800km day on an RS or RT would likely feel significantly easier.

Yes, riding long rides regularly makes it much easier if you also make sure your ride is comfy.

The same is with a car. When I first learned to drive I would get exhausted after an hour. Now I can drive 1000km in one go and still be fine. Over time, your brain learns to do things on autopilot which unloads your brain, you learn to set yourself up in a comfortable position, you learn to not be tense all the time, you learn to predict more things more time in advance which means you can handle them with more ease. And the body itself just learns the new position and things shorten/lengthen to make that position a little bit more comfortable.

The main difference between bikes and cars is that people rarely spend so much time on a bike as regularly as in car. So we get accustomed to driving quickly but it takes time to do the same on a bike.

Fortunately I have a high windshield so it's not so bad in terms of wind. And if anything the wind pressure on the rest of my body makes me forget how sore my bottom is, so I'm not sure that's really linked to the wind.

- A good helmet to cut down on noise.

- Good riding posture.

- Stretching and walking around for a few minutes at gas stations.

- Stretching on the bike: standing on the pegs for a few minutes every so often, switching riding positions, putting your feet on the passenger pegs.

- Walking, standing up, lying down... anything that isn't sitting when not on the bike.

Yes I do all that but still it's very uncomfortable after a few hours. But I am not used to sitting in my daily life so I guess that doesn't help.