Why I Ride With Very Loose Reins
Look at any photograph of me riding and you will notice the same thing: the reins are loose. Very loose. People either commend it or ask what on earth I am doing, and both reactions are why I am writing this down.
First: ride however you and your horse are comfortable. There is no single right way. I am explaining why I ride the way I ride. Do with it what you will.
Two kinds of pressure
When you work with a horse you apply two kinds of pressure.

The first is steady pressure, and most of it is unintentional. Eye contact. Facing the horse square with your body. Any movement of your hands on the reins. Taking the slack out, or keeping constant contact with the bit. Applied constantly over time, a horse becomes desensitised to it — he learns to ignore it. That is why your horse does not react when you look at him, and why a dude-ranch horse does not slam to a stop and back up when a tourist picks up the reins.
The second is a cue: pressure applied with the expectation of a response you have already taught. Squeeze with the legs and he speeds up. Pull a rein to your hip and he bends.
The two work together. Steady pressure sets a baseline, and anything outside it is what the horse reads as a cue. So you want the least steady pressure you can manage, because that is what lets the horse be soft when you ask.
The restaurant
If that was confusing, think of it this way. You are in a loud restaurant trying to hear the music. The crowd is steady pressure. For the music — the cue — to get through, it has to be louder than the crowd. In a quiet room it barely needs to be turned up at all.
How you hold the reins is the volume of the room. If you ride with a death grip, you have to pull even harder for the horse to hear you over it. If you ride with no contact at all, the room is quiet, and the softest cue is heard.
That is the whole secret to a light horse, and it is why I ride with loose reins. I want no background noise, so my horse hears me the moment I so much as pick up.
How loose
Neutral. Wherever you hold the reins, there should be no contact until you mean it: slobber straps not lifted, nothing on the bit.
For most horses I aim for a 10 foot rein and hold my non-dominant hand in the middle of it, resting on the withers. The other hand is free to pick up when I need to turn or bend. Working on collection or vertical flexion, I keep a small coil in the rein — watch Buck Brannaman and you will see it — still with no steady pressure.
A lot of reins on the market are 8 feet. Having ridden extensively with both, I will say plainly that you need 10 feet if you want a truly soft horse.
I have tried almost every rein out there — I am not exaggerating — and settled on our 10 foot loop reins: heavy, full of feel, the right thickness, with weighted ends that let you pick up softer still while the cue reaches the bit. My own favourite is the 22 foot mecate, which does everything the loop reins do and adds a lead end for ground work, a quirt under saddle, and tying on the trail when done properly. Most natural horsemanship trainers ride in a mecate. I set mine to a 10 foot rein, and they adjust for a draft or a pony.
Riding with loose reins changed how I ride and I am not going back. It is better for horse and rider both. Try it.
On pressure and release: I train every horse this way. I ask with a cue, apply escalating pressure, and stop the pressure the moment he searches for the answer and is on the right track. It is the most consistent method I know, and it keeps the horse in his natural, herd-oriented mindset.