Towards the end of a ride (after about 3/4 of an hour) my horse shakes his head up and down, if I give him his head he stops. His teeth and back are fine. I tried a hollow bit instead of his solid one and this made him worse. Has anyone got any suggestions? He is ridden in a loose ring jointed snaffle

If you ride the same route or for the same amount of time horses become accustom to it and know when the ride should be over. My 30 year old knows the route we take well and if I decided to stray from it he will put up a little fight. So I began to change things up I try not to go the same way each time or I will do the route backwards. Just a suggestion, sounds a little behavioral.

Does it appear like he is trying to get the reins away from you/get more slack?? Or is he just tossing it up and down for no obveous reason? I've had several horses that would toss their heads, more so if they were going in the direction of home, but it was to get more slack out of the reins...