Does your horse spend more time looking to the outside of a circle than he does the inside? If he does he’s not going forward correctly. He may feel as if he is and you may well be using as much leg as you possibly can but if he’s not in both hands this is a battle you’ll never win.
Your horse is going forward correctly if he moves forward willingly and he accepts the contact in his mouth. If he resists your contact or you don’t maintain it you might as well stop pushing because any energy you do create will be lost.
Many riders assume if their horse is bent correctly they should have very little weight on the inside rein. They’ll push with their inside leg checking and releasing their inside rein in order to get their horse ‘off it’. In truth they should do the opposite.
Your hands control everything in front of your saddle. Drop the contact on your inside rein and your horse will drop his inside shoulder. His head and mouth will copy his shoulders. If his mouth is lower on the inside, and therefore higher on the outside, his head will tip to the outside.
With little contact on the inside rein your horse may feel heavier in your outside rein. Understandably you then feel you should lighten the outside to match the inside. You drop him off it. Now you have no real contact on either side of his mouth.
Many riders misunderstand lightness. When a horse is light in your hand it doesn’t mean nonexistent. It means he’s waiting at the end of the rein - and willing - to react to your next aid. There should always be some weight in your hand otherwise how else can you control his shoulders or contain his energy?
If your horse is heavy in one rein it means he’s not in the other. The best thing you can do is take up the contact on the other rein to match it. Don’t worry if he feels strong. (This will take more than a couple of strides to correct so don’t grab the other rein and after two steps throw it away saying “I told you it wouldn’t work!”)
Your aim is to ride large round the school with an even amount of pressure in both hands. In an ideal world that would be a fairly elastic, relaxed pressure but if this is a regular habit your horse may put up a bit of a fight. Do whatever it takes to keep the pressure even on both sides of his mouth. Follow his mouth with your hands.
Be consistent. Even pressure and level hands will keep your horse straight in his head, neck and shoulders. Keep your fingers moving on the reins so you can’t lean on each other. Bend your elbows so you don’t set your arms against him and ride forward.
Ride circles, turns and serpentines. Use a strong inside leg but forget about bend. Keep the same weight in both hands and your horse’s head and neck straight in front of you.
When he realises you’re not going to change or give in your horse will do two things. First he’ll relax his mouth which will have an instant effect on his topline. If his back relaxes he’ll start to step further under his body with his hind feet.
As his topline relaxes he’ll feel the extra pressure from your inside leg. He’ll bend his body away from it leaving his shoulders and quarters where they were. In other words he’ll bend around your inside leg. Without you pulling his head round.
The next time you’re struggling to get an inside bend change tactics. Ride your horse straight for a few circuits, put him in your hand not off it. He’ll soon come round.
Good luck and enjoy your schooling.