Does anyone else have this problem? I'm tired of cleaning up and don't want to stink up the place for other people.

I've had several horses and all of them liked to pee in crossties. Geldings like to go after a ride. One mare that I had waited all day to get in to do her number 1 and 2 so I had to start taking her to her stall first before grooming in the crossties.

I had one of these horses' urine analyzed (no kidney stones), none of them had sore backs or other health issues.

Might it be that the horse smells that another one has peed in crossties and therefore thinks that it is OK? Or might it be a relaxing thing?

Any advise on how to prevent this? The gelding that I have now will go as soon as I turn my back on him (e.g. to take the saddle to my locker).

Tack him up in his stall

The problem with this gelding is that he doesn't have a stall, he is on outdoor board. I could take him to another horse's stall but at the moment horses that have indoor board are in during the day so I have nowhere to put him.

Can you tack him up outside?

As horrible as it sounds... I used to whack my horse's stomach every time he did it (He used to do it ALL the time as well, same as your guy). After a couple times of getting a decent whack, he figured it might be a better idea not to do it... Hasn't done it since! (this was 6 years ago!)

A gelding i ride lives out during the day, and no matter what time you bring him in, if you don't put him in a stall, he'll poop in the aisle. So, immediately from outside, I put him in his stall, and wait. Once he poops (and quite often pees as well), then I'll take him out to tack up.

My gelding usually pees in cross ties after a ride. Usualy when I take my saddle back to the take room. I've started taking his bridle and saddle off and then right away putting him in his stall.

I don't know what I would do with an outdoor horse if he were doing this. It's a difficult habit to deal with for sure. Messy!

my mare always poos before ride, and pees after ride, no matter in stall or crosstie. i just tack her up in a stall, less mess to clean up.

since you don't have a stall, tacking up outside is a way to bypass the mess and stink.

Yes unless you can put him in a stall for a short time before and after you ride there is not much you can do, try the suggestions mentioned. I had a gelding that no matter what I had to put him in his stall right after I rode him. And then I learned at shows that he needed to pee after each test, so we had to load him up in the trailer so he could go. Though he did finally learn to pee outside. It's a real pain when you have horses like this.
A coach of mine was telling me she had a stallion that even at shows she had to warm him up and then get off take him back to his stall so he could pee otherwise he didn't perform well in the ring.

all I have to say is this: gotta love our horses, eh? ;D