Just a warning about the one rein stop or pulley rein on a bolting horse, it is very easy to make a running horse fall by taking his head away at the gallop, especially if the terrain is varied (ie if there is a footing change). On horses that are known to bolt why not teach them to stop properly before getting on? If it is just a regular spook, ride it out without pulling, a horse will only go a few strides before his curiosity slows him back down.

Bolters get worse when fearful people ride them, say the horse initially spooks and then the rider grabs its face, clamps down, stops breathing and totally confirms that whatever the horse spooked at was a serious threat and he should keep running. Or there is a pain issue involved, a horse trying to get away from back pain or mouth pain that is just made worse by the rider. I've seen horses take off unload the rider and keep going until they could be relieved of the painful pressure of an ill fitting saddle.

There are also so many horses these days that are taught that "pull means go" when riders are taught that pull means stop. No wonder there are problems. I teach all of my horses to stop if a rider becomes unbalanced or comes off (whether that is a fall or a dismount at a walk, trot, gallop) so that there is less of a risk that a horse would drag someone to death if they got hung up. I would encourage people who feel athletic enough and are wearing proper safety equipment to test out their horses in an enclosed area, step off the horse at a walk and see what happens. Then at least you will know whether your horse would be inclined to drag you to death or not. And teach that horse to stand solid for mounting and dismounting and to stop when a rider starts to get off before putting a child or your grandma up in the saddle.