Photo credit: Harry Furey.
This suggestion is for those riding and those who are not able to ride. I find it surprising how often I have to teach riders how to shorten their reins. Seems easy, right?
First of all, normally one should not shorten the reins by dropping and grabbing the rein with the hand on the same side as the rein – right hand jumps forward or even crawls forward on the right rein to make it shorter. This causes the contact to be dropped and then often grabbed back or at the very least to wobble. One should reach across with the thumb and top finger of one hand, pull the rein through the other hand – taking the rein on top of the thumb and first finger of the opposite hand. And when you shorten the rein your hand should slide forward on the rein. Usually we do not shorten the rein to make it tighter, but to have the hand further forward. The hands should normally be in front of the pommel. If you hold your hands too wide or too low, this will be impossible to do easily. Your hands should be held near each other.
So my challenge to you is to play with shortening your reins and think carefully about what he horse feels on his mouth; remember the bit at the end of your reins lies on his bare gums. He should not know you are shortening your reins. Those of you in the house, get some narrow belts or twine or reins if you have them, and have someone else hold one end, or tie them to the back of a chair. Now see if you can shorten the reins without the other person feeling it or having the reins get looser or tighter as you do it.
As I was looking for a video to share I was surprised to find people telling you to shorten the reins the way I tell you NOT to – and you can see in the videos how the contact gets tighter and looser as they do it.
This one explains it the way I think you should shorten your reins: https://www.youtube.com/watch?v=TUCvR0gIR5E.