Tack: Auxiliary Equipment
Side Reins

By Karen Nelson
January 2009
Back to Tack Index
Side Reins
Used For:
This is considered a lunging and ground driving equipment only. The only
time it should be used with a rider is for ridden lunge line work. Side reins
are used to teach the horse to give to rein pressure in a very simple way.
How they are put on:
Side reins are two reins, usually with some give, that attach from the rings of the bit to the girth or  to the rings on a
surcingle. Side reins should only be attached to a snaffle bit, preferably a smooth snaffle with rings that are unlikely to
be pulled through the mouth. Side reins can be used with some bitless options such as a side pull, but should not be
used with any sort of hackmore or other leverage device.

Side reins should be adjusted so that both reins are of equal length. They should be adjusted loosely, or left undone,
until the horse has warmed up, and then adjusted accordingly for the training/experience of the horse, as well as the
gait they are being worked at. Ideally the side reins should be attached to the girth or surcingle at a point equal to, or
higher than the point of shoulder.

Draw reins are best used at trot only, as they do not allow for the natural head bob of the walk and canter. They are
suitable for lunge work over low caveletti, but not for jumping.
How They Work:
Side reins are quite simple; if the horse tries to put its nose beyond the length allowed by the side reins, then the horse
will feel pressure on the bit until they put their head back within the allowed range. The angle of the pressure depends
on the position of the horse's head, as well as how they have been attached to the girth/surcingle.

As most side reins are elastic, they allow some give with increasing resistance. Elastic side reins offer the most
"warning", with "donut" types being less forgiving. Solid leather side reins do not offer any give.

Side reins are useful to teach a horse to give to pressure. It is best to already have instilled the idea of giving to
pressure prior to using the side reins with groundwork, otherwise the horse may not know how to get away from the
pressure and may end up damaging their mouth and trust in the bit.
CONS/Risks of using Side Reins

1) As the side reins don't allow for the natural bob of the horse's head, nor do they allow for the horse to stretch for
lengthened gaits, the side reins may cause the horse to stiffen its neck, which will in turn disrupt the flow of the horse's
gaits. For this reason side reins should only be used for a steady trot, and not for walk and canter work.

2) Side Reins are often used to force the horse into a frame, however the result is usually that the head is pulled into
position rather than the horse being encourage to use its back. Side Reins used in this manner (over tightened) usually
end up pulling the horse onto its forehand, teach it to break at the 3rd vertebra, or teach to travel behind the bit.

3) Some horses will learn to pull into the side reins in order to keep them and the bit steady. Horses typically prefer a
consistent contact over an intermittent contact, which effectively jabs them in the mouth.

4) If the Side Reins are adjusted incorrectly, and the inside one is adjusted shorter than the outside, the horse will have
its front end pulled into the inside of the circle resulting in an over bent or crooked horse.

5) Donut type Side Reins add considerable weight to the reins, and if the horse allows one to go slack, will experience
considerable bouncing and annoyance by the donut, and be in effect "punished" by giving.

6) Side reins done up to the side of the girth/surcingle, will punish a horse for wanting to stretch. When the horse goes
to stretch, his head will be pulled down and IN towards his chest. Anyone who has ridden a horse who has learned how
to get behind the bridle will know that this is a difficult habit to unbreak!

7) The horse receives as much (or more) release for getting over bent and sucking up and back, as it does for carrying
itself on the vertical.

8) Users tend to leave side reins on for too long, leading to the horse's neck cramping and the horse getting
uncomfortable. 5 minutes in side reins may be more than enough for a green horse. A horse should NEVER be let
loose, or left in a stall with side reins.

9) Side reins done up between the legs are extremely dangerous as it is easy for a horse to get a leg over the side reins
if it stretches down. The pressure on the bit is downward, forcing the bit to break up and back into the horse's palate,
while the bit is brought down and forward onto the bars...not how a bit is meant to work. Side Reins should NEVER be
used in this manner.
Shown here are examples
of different types of Side
Reins: From left to right:
Elastic Insert, Rubber
Donut, Solid Leather.
The side reins are put on at equal length, with the purpose being to teach the horse to stretch into the outside rein into
the arc of the lunging circle. This helps set the horse up for future work "inside leg to outside rein". The side reins
should not be used to create the bend, rather the lunger uses their body and lunge circle to create the bend in the
horse. It is important to remember that the horse should carry a consistent arc throughout their body, from poll to tail,
so the side reins can also be considered useful in limiting the amount of "bend" the horse is able to achieve with their

Side Reins should not be adjusted so tight that they restrict the horse's
neck from stretching out, they should only
restrict the horse's nose from being overly poked out, or from being over bent side to side. They also should not be
used on an overly fresh horse, as serious damage could be done to the horse's mouth if they decide to "play". A trainer
should always strive to keep a horse's confidence in the contact.

Side reins adjusted this way are also useful to help keep a horse reasonably straight for ground driving, and to
decrease their ability to evade contact, as well as to keep a trained horse in a "frame" for lunge line lessons.
This drawing illustrates three different head and neck positions "Allowed" by the
side reins:

The black position shows the ideal; neck stretched but with some arch, and nose
slightly ahead of the vertical. This is the tightest side reins should be adjusted.

The Red position shows the horse coming above the bit, likely with a hollow back.
The pressure on the bit will be down on the bars, and up into the palate (if a jointed
snaffle is used. If however the horse keeps its head within the range of the draw
reins, no correction will be felt by the hose.

The Yellow position shows the horse attempting to stretch down with its topline,
however the draw reins react by pulling the horse's head towards its chest. The
horse would be rewarded if it tucked its head even more towards its chest, thereby
risking teaching it to get behind the bit.

The trainer must watch for these mistakes, and encourage the horse forward to
correct them, and must keep sessions short.