Donut side reins are stiffer than elastic but more forgiving than solid reins. Photo by Beth Benard.

Of course you know what side reins are, but maybe you’re a little fuzzy on what they’re supposed to accomplish. In fact, you might admit you don’t know how to use them and wonder if you should. Side reins are an essential part of the training routine and once you understand them, you’ll wonder how you made it without them. 

Side reins are adjustable lengths of material that connect the horse’s head to either a saddle or a surcingle. They can be cotton, leather or nylon.  Some are solid, others have elastic sections or rubber “donut” inserts.  No matter the style, they all have the same purpose: to teach the horse to accept light contact with the bit.

But can’t I do that while riding? Sure, if you can guarantee you’ll:
• Never be out of balance.
• Always have an unvarying amount of feel in both reins .
• Consistently tell from the saddle exactly what the horse is doing with his mouth and if he’s pushing through equally from behind. 

Longeing in side reins affords the horse a reassuringly consistent contact that the average rider only dreams of offering, and it allows you to evaluate and influence the acceptance of the bit, the horse’s frame, bending and gaits.

The Equipment
When selecting the style of side rein to use, consider the horse’s level of training.  If you’re starting a youngster who’s just been introduced to the bit, you want a forgiving, sympathetic side rein, and that means elastic.  On the other hand, if you’re re-educating a horse that’s spent 15 years falling on his forehand or has been ridden with strong aids, you want a sturdy side rein with little or no “give” that he’ll eventually learn to respect.

We’ll begin with the youngster and assume he’s wearing a well-fitted bit, surcingle and longeing cavesson, essential pieces of equipment that we’ll discuss in an upcoming issue.

Longeing with only a bridle is not a good idea, as it’s almost impossible for a horse to understand “go lightly on contact” in side reins when the bit is being sawed back and forth by the longe line attached to either the inside bit ring or over-the-poll, outside bit ring. 

Longeing with a halter is nearly as bad, as there’s no way to prevent the check pieces from sliding up and gouging the eye area. A longeing cavesson affords much more control than even a chain, which, besides being harsh for longeing, must be removed and rethreaded through the halter when the direction is changed.

Put It To Use • Longeing in side reins is hard work. Done correctly, it’s weight lifting for the horse’s back, abdomen and hindquarters. You’re asking him to use his muscles in a new, more- demanding way. • Allow lots of breaks and plenty of praise. No training session on the longe should exceed 30 minutes. • Your goal is to have the horse trotting freely forward with his head and neck stretching into contact with the bit, with a closed mouth and his head slightly in front of the vertical. • Allow plenty of time and enough longeing sessions so you arrive with a happy, willing horse.

Getting Started
Lead the horse to the longeing area with both ends of the side reins attached to the surcingle only and put him through his longeing routine, letting the side reins flap against his sides. After he’s gotten the kinks out, adjust the side reins so they’re long enough for the horse to stretch down as far as his knees with his nose poked well in front of the vertical. Next, attach the side reins to the cavesson (not the bit).

It’s not unusual for a youngster to panic when he first comes up against the feel of pressure on the bars of his mouth coupled with his head and neck being restricted, so introduce one sensation at a time. Even the most over-reactive types will usually accept the limitations without this type of crisis if you go slowly.

You’ll initially attach the surcingle end of the side reins horizontal to the ground.  This prevents the horse from inverting his frame, moving with his head up and back dropped. Over time you’ll slowly raise the side reins until they assume the position and angle that corresponds to where the riding or driving reins would be held. 

If the horse begins to invert, drop the side reins back down to the D ring where the horse could comfortably travel in the correct frame and try to raise them again later as he gets stronger.

Once the horse accepts the reduced range of motion in his head and neck—which may take minutes or several longeing sessions—you can safely attach the side reins to the bit. Leave them the same length as before, so the first contact the horse makes with the feel of side reins to his mouth is nearly incidental. 

While you’re longeing, verbally praise the youngster every time you see him come up against the bit and then flex his head away from the pressure.  If the horse remains relaxed, you can begin shortening the side reins, equally on both sides.

If you see the horse “root,” jamming his nose toward the ground after you’re several days into the shortening process, switch to a less-forgiving side rein, like a rubber donut.  The donut limits the stretch, but it still has an element of “nice” to it. Many horses, however, are respectful of the bit and can spend their longeing careers contentedly working in elastic side reins.

Start The Training
Ask yourself these questions:  Is my horse bent absolutely perfectly along the arc of the longeing circle?  Is he tracking up equally behind, with a nice over-stride?  Does he have a steady rhythm and is his tail carried away from his hindquarters and swinging at the trot?  No?  Adjust the side reins.

Ideally, horses will take equal contact with both side reins when longed in either direction, but that rarely happens, especially in the early stages.  If your horse is bent to the outside, you need to shorten the inside side rein enough holes or Ds—normally not more than 2 or 3—so he is now evenly bent from nose to tail on the circle.

If his hindquarters then fall out, you may have overcorrected for his current level of flexibility and will need to make the change of bend more gradual as he gains strength. If he overbends to the inside and tries to make the circle smaller, the outside side rein requires some shortening, and don’t hesitate to point that longe whip with some authority at his shoulder.  Remember to go back to the neutral—or an even-length of side reins—when you switch directions.

Sliding Side Reins Sliding side reins are relatively recent inventions that haven’t been accepted by many purists, although they’re popular among the driving aficionados.  Sliding side reins look like draw reins, as they’re attached to the surcingle, slide through a snap at the bit, and then back to the surcingle, but their mechanics are different.  Whereas draw reins use the bit to initiate a pulley action, sliding side reins allow the horse to assume a comfortable, and changeable, neck position without avoiding contact. We used Top Tack’s Rebalance sliding side reins on an older, wise FEI-level dressage horse that characteristically over-flexes and then leans on the bit, both on the longe and under saddle.  To our surprise, he assumed a nice frame, advanced his nose almost to the vertical, and demonstrated lovely suspension. Next, we fit them to a young horse with a high head carriage, a sensitive mouth and a habit of traveling quite inverted.  As expected, he had a panic attack when he discovered his usual evasions wouldn’t relieve the contact.  During the second longeing session with the sliding side reins, he eventually found a head and neck position that allowed him to travel comfortably and be only slightly worried.  In subsequent sessions, he seemed to relax a bit more as he investigated stretching his neck even further down, which conventional side reins prevent him from doing. Sliding side reins aren't the answer to every training problem. We recommend you only use them under professional supervision, as both placement and adjustment seem to be critical to their effectiveness.

What if he’s bent correctly through his body, but his nose is tucked towards his chest? Check to make sure your side reins are long enough to allow his nose to come in front of the vertical at the trot and then ask for more activity and push from behind.  Remember, the key is “go forward into contact.”  If this is a horse that habitually rolls up his neck, even under saddle, also consider changing to a mild bit and using side reins with the elastic inserts. Ideally, the reins should eventually be the same length on both sides.

Now, how about the older, on-the-forehand, feet-dragging-in-the-sand horse? Again, send him forward. Not necessarily faster, but definitely into an active, animated trot. Use side reins that provide some negative reinforcement if he leans on them.  This is one of the few times where solid leather, nylon or web side reins with no “give” are the tools of choice. 

Do tons of transitions, not only between gaits, but also within gaits:  trot, extended trot, walk, trot, canter, walk.  You’ll be surprised how interested he becomes in his training and how light he’ll eventually become in front.  Don’t forget to adjust for the correct bend, as a horse that demonstrates lack of flexibility front to back is probably also stiff side-to side.

Overcoming Obstacles
We can’t address every training obstacle you might encounter, but we’ve covered the most common ones. Don’t hesitate to experiment with different styles; compared to most tack, side reins are a bargain.  Just remember:
• The horse’s nose should never come behind the vertical.
• Don’t use side reins when you’re riding unless you’re longed.
• Leave the draw reins, chambons and other pulley-type devices to the true experts.
• Adjust, watch closely, readjust. Start out your session with side reins looser than normal and gradually shorten them as your horse’s muscles warm up. Don’t assume he’ll always go best with the side reins set at the same lengths and position as the day before.
• Never leave a horse in a stall wearing side reins or tied with one side rein forcing his head around. It makes no sense from a training standpoint, and it’s cruel.
• Never walk the horse for extended periods of time in side reins. Half a circle is about the maximum. He needs an unrestricted neck in order to swing his back at the walk.  Young horses, especially, can develop lateral walks if not allowed that freedom.  When you’re giving your horse a breather, unhook the side reins and allow him to relax (but keep him marching along; it’s not a lunch break).
• Always unhook the side reins from the bit when you’re making adjustments in length; you can give the horse a nasty jolt to the mouth if the buckles stick.  And never unhook the surcingle end with the side rein attached to the bit.

Tricks of the Trade To keep the surcingle from rolling en route to the ring or during your warm-up when the side reins aren’t yet attached to the bit, take an old leg wrap, tie it to a D ring on the near side, cross it over the withers, around the chest and then attach it to a D on the off side (see Photo 1).  This works especially well for chunky horses lacking prominent withers and also allows you to introduce the surcingle to young horses without having to tighten the girth to eye-popping tension, making their first experiences more pleasant.  Because many of our side reins were constructed of quality nylon or cotton web probably capable of towing a car, they lack the fail-safe component we prefer. You can add that element of safety by making a loop from a leather shoelace and attaching it to the surcingle D, and then threading your side reins through the leather loop, instead of the D. This works equally well on a saddle D or girth. Any horse, no matter how well balanced, will at some point trip, stumble, spook or have his legs shoot out from under him. On those rare occassions, the shoelace will break, hopefully preventing a serious neck wrench or fracture.

Bottom Line
None of the side reins in our trial were deficient in any aspect, and any one of them might be perfect in the right situation. Don’t hesitate to experiment to find exactly the right set. Listen to what your horse is telling you. When you find the right set, you’ll know it and so will your horse, which is really the bottom line. 

Prioritize your requirements. If easy adjustment is paramount for you, you can’t beat the models that offer sewn-in Ds and snaps, like Top Tack and Dover Easy Adjust.

If you need a pair that will work on lots of different horses, choose a style that allows for the maximum amount of size expansion, like Perri’s Leather Elastic, Dover’s Leather Elastic or  Fabri-Tech’s multi-holed options.

For fine-tuning the length, go with leather. Tory’s side reins are beautiful, and you can punch many additional holes without compromising its strength. If you simply can't make up your mind and your're reschooling your horse, deciding side reins may be just the ticket to help, the Fabri-Tech Rubber Donut side reins pleased most of our testers, offering a midrange level of stretch and fell for most horses.