You may have the reins too short for his level of fitness and training.and no, don't ride with them.
The difference in riding him vs side reins, is usually riders forget to keep asking for a constant "give" You ask, he gives, you stop asking, go on and do something else, then you ask another time, and he responds. Side reins never quit asking if he relaxes again, they ask again at that same spot. It's also hard on muscles that flex the poll, he doesn't normally walk around with his nose vertical, does he? For side reins, initially, just use them in short bursts, for a few rounds this way, and maybe a little longer length than you want at first. As long as they make contact if he's relaxed, but not cranking his head back behind the vertical, he's still learning. If you over-shorten them, he gets very tired and feels trapped, and you can actually teach him to LEAN into the bit.He needs to be able to find that release.
A good guide, until he's more fit, is to rein him back for a few laps, and the adjustment should start with if you have the rein unattatched, the side rein would reach about to the throatlatch area, then snap it to his bit. When he's longed, have the "outside" rein a tiny bit longer so he can flex into the curve of the circle. When changing direction, change it. This also avoids the nutcracker effect of a jointed snaffle bit, by making the pressure slightly uneven. Initially, just a few laps, at gait of your choice. When he's softening up, stop and detach the reins, let him move out uninhibited, then re attatch. This reffrims in his mind he's doing right, and lets him stretch his muscles. Don't forget to change directions and repeat. He'll be softer on one side, and that's the side you should work more in general (I ususally start on their stiff side, then work on the "good" side,then end with the stiff again, to work it more for eveness). You can tell if he's really giving or is "held" back by the lack of tension in the reins. If the reins are taught, he's not really giving. And a frothy mouth does not necessarily indicate he's fighting it, just that his mouth is active and slobbery, but if that's not normal for your horse, then he's probably leaning on the bit and not really giving.
When you ride, work on asking for the give and keep him in it for extending numbers of strides. As his neck becomes conditioned for it, he will find it easier to hold longer before you ask again, and his neck will LOOK different (and prettier!)
Do not ride in sidereins. They could interfere with your abiltity to steer your horse in an emergency. If you need to do an emergency one-rein stop, he can't turn his head around and will fight you harder.
Last edited by barefoothooves; 02-25-2009 at 03:18 PM.