When I started eventing, way back in 1983, one of the first things my trainer explained was how to bridge my reins. She had me use the bridge when galloping: it gave me more security, gave my horse a constant, steady contact, and kept the reins from slipping through my fingers (or being pulled through by a strong horse). Since then, I’ve found that I bridge my reins a lot. It’s very useful when you’re hacking and want to hold the reins in one hand, when you want to keep your hands quiet, when you’re riding a strong horse, or when you want to keep yourself from pulling back. I still do this sometimes when I’m approaching a fence because it keeps me from fussing with my horse’s mouth.
You bridge your reins by crossing or folding the slack in the reins, then placing that fold across the horse’s neck. You then press down on either side of the horse’s neck, removing any slack from the reins. The bridge is held approximately where the neck strap of a martingale or breastplate would be located.
While bridging your reins is a fairly simple maneuver, I’ve found one product that makes it even easier to switch back and forth between bridged and unbridged reins. Mailer Bridging Reins are probably something I should have bought years ago: it would have saved my trainers from yelling “shorten your reins” about a million times!

Two that I’ve come across that both get very good reviews from users are:
To bridge your reins, you hold them as you would normally but then turn your hands slightly to face thumbs briefly as you adjust your reins to the bridge. As the rein passes through your thumb and finger, it now goes across your horse’s neck to the other hand, where it also goes through your thumb and finger. Doing so on both reins now allows for a bridge. Then return your hands to the normal position while maintaining the bridge.
Bridging the reins gives the rider a bit more security with horses that try to pull the reins from their hands. A common technique used by those riding very forward cross country, bridging the reins also helps riders who have the bad habit of opening their fingers and allowing the reins to slip through their fingers or who are often losing contact for whatever reason. It helps the rider regain the contact without too much fuss and does not restrict the horse. It also helps riders consistently maintain contact when they are learning how to judge contact and when to fix it. Additionally, bridging the rein helps beginner riders maintain awareness of where one hand is in relation to the other; the technique assists in keeping the correct spacing between hands as well as keeping them from being held too high.
Riders who fuss too much with their reins can benefit from the technique as well as fussy horses who are affected by inconsistent contact.
Reins can also be bridged to just one hand so that you can ride single-handedly over jumps. Doing so helps the rider maintain her own balance and helps keep her from leaning on the horse’s neck. It also helps in exercises for building independent aids, such as jumping with one hand out to the side. To bridge the reins to the single hand, hold the outside rein normally as you would, then place your inside rein over the top of the outside.
I bridge my reins quite often. When I’m hacking out, I often use a single hand bridge and when I’m hunting, I use a bridge to keep my reins from slipping through my hands. Even better, I hook a finger through my neckstrap and then I feel quite solid in my contact but never like I’m pulling back on my horse’s mouth.
that’s a great reminder. i always forget about bridging the reins, and doubt i’d have the presence of mind to do it in front of a jump without a lot of practice and concentration 😐 but it’s probably worth the trouble to add that one to the tool box. thanks 🙂