Why do I get a sore arse on a long trip?

[Maki]

Cycling shorts are good I reckon. We have it good compared to pushbikers, look at the tiny things they call saddles.

[Burtha]

nappies?

[firefighter]

Taking out your buttplug will help!

[slofox]

Yerrr sore bum is par for the course for me too. (It's coz I DON'T have a huge fat arse is why I reckon...!)
Course the SV has a pretty basic and friggin hard seat as well which doesn't help. Two hours without a break is about max for me.
On the other hand I have few other aches on longer rides. I tend to put a lot of body weight forward onto the bike so I carry almost none through my arms/hands. In sweepy bits I try to have NO weight at all on the bars - bike handles way much more betterer that way as well, because I am not interfering with its natural balance.
I also use a Scottoiler "cramp buster" or throttle buddy which means I don't have to hold the throttle grip so hard. I have a lot of scar tissue in my right hand from surgery last year and find this device helps a lot. Without it (and some days even with it) my hand totally numbs out and I can't feel a thing. Have to let go and shake the hand a bit to restore circulation...
Knees get sore too after about two hours. Forward position is how I love to ride but it plays hell with old buggered up knees like mine. I have to get off every so often for this reason.
BUT overall I wouldn't stop riding for anything. I will put up with a little pain in exchange for the sheer joie de vivre that riding a bike brings into my life. Very little compares with that...

[CookMySock]

Just keep riding and it will come right. Its no different for your wrists, neck, legs, etc. Bikes are great for getting everything a good click into place.

Steve