Alright, I'm going to try to keep this fairly short and sweet and to the point. I'm still a fairly new horse owner. I got my gelding, Tigger, last March, so I've had him for a little over a year. I only do trail riding as of right now, and I'm having some difficulties with him.
At about 16.3 hands, he's not the biggest horse in the world, but Tigger is also very long, considering he is a Thoroughbred-Quarter Horse mix, which means he has a lot of muscle and sheer strength. Weighing about 1350 pounds, me, at 130 lbs, am at a disadvantage. See, the thing is, Tigger loves to run.
Whenever I go trail riding, I go with a group, and we will race each other down long stretches of the trail for half a mile or so at a straight gallop. The others will pull back and say 'woah', and their horses come to a stop in about 20 feet. I pull back and say 'woah'...and Tigger keeps galloping. I pull back even more, until the reins are against my hips, and Tigger keeps galloping. I pull back until I am standing up halfway and his chin is against his neck and I am certain I am hurting him, and he will only then slow to maybe a canter, and then a fast trot, and then kind of walking. Do you see the problem?
It takes me about 300-400 feet to get him to stop, every single time. It's dangerous for both me, him, and other riders, because sometimes we are coming towards a very rocky patch of the trail and I am afraid he will hurt himself, or stop all of a sudden and throw me off. One day he could run us into other riders and hurt himself, me, and them. It's also embarrassing because others says I can't control my horse.
On the ground, Tigger is a really great horse. He leads perfectly, lunges fairly well, stops when I stop, picks up his feet for picking, and is just plain respectful, usually. Whenever I tack him up he gets a little dancy, but more like he is excited than testing me.
I know this post is getting ridiculously long, so my main question is:
Should I change my bit? I use a 5 and a half inch tom thumb bit, and some of my friends say to get a curb bit for more control and assertion, but I feel as if that will make the problem worse rather than help. Guys, what should I do?