So my gelding likes to buck away from home. He has been hauled to shows and schoolings all over. I have yet to get through a horse show or even make it to an event because when I take him to schoolings and schooling shows he bucks and it is only when we canter. I can ride him at home and he is just fine or even go on a trail ride or hunter pace and he behaves. I have had him completely vetted and a saddle custom fitted to him. Nothing crazy going on vet wise and he gets regular chiro. At our next outing we are going to try some perfect prep but he is not a hyper guy, he is a lazy luggy warmblood!I think I have created this problem and need help! I have now lost my confidence! 
Sounds like he has learned bucking gets him out of work. If your not confident enough to ride him through it (which is completely understandable), I’d try getting a pro to ride him away from home to show him he is not allowed to do that.
Ugh, sounds a nasty problem.
Have you tried lunging him at shows, particular in canter to get the bucks out before you get on? Seems like shows unnerve him…is he staying overnight? Maybe try going for long hand walks and hacks around show grounds and lunge before riding.
Also, do you ride differently at shows? Many riders are more keyed up/tense at a show so he could be responding to that as well?
Good idea having a pro ride him at shows/warmup ring as well.
A few questions. OK, more than a few …
Is he bucking in the warm up or in classes or both? Is it a “get off my back” buck or more like a “wheee!!! I’m gonna canter” buck? And what do you do when does it?
I went through one show in which my horse was great in the warm up. Then we’d get in the class and he bucked in every one of them, mostly on the canter depart, but also at the trot once. He even threw in a crow hop on our victory lap, too. (It was a rail class and judge hadn’t seen his antics. :p)
I finally got with the program in the last class and when he felt like he was ready to do his thing, I put him on the outside rein. Firmly. Half halt with my seat, ask for a little flexion with inside hand, outside hand like a wall and give him a good push with my inside leg.
Suddenly, it was much harder to buck and since he’s a lazy boy to begin with, he decided not to. 
Hope you can find an easy solution.
