It has become very common to see riders (especially those who ride Western) with long stirrups. While it may seem comfortable to ride straight legged, shortening your stirrups can really change your riding for the better. Here's how:
1. You will be able to keep your heels down better.
Every rider has heard: "Heels down!" at least two hundred thousand times. What you don't hear very often is why you need to do it. A rider who keeps their heels down looks great, but there is a lot more to it than that. Your heels are your anchor. They are what hold you down in the saddle. When you drop your heels down, you are flexing your calf muscles which helps you lock you leg in place beneath you. If your lower leg is freely swinging around, you lose your anchor.
If a rider's stirrups are too long, it makes keeping the heels down very difficult, and in some cases impossible. If the stirrups are not adjusted to the proper length, you will be straining to reach them by pointing your toe. That is the opposite of what you should be doing. By raising the stirrups, you will have greatly increased your ability to keep your heels down.
2. You will be able to maintain proper lower leg position.
It's important that riders have their legs underneath their hips for good balance. Think of proper riding position as standing up with your knees slightly bent; don't think of it as sitting in a chair. Has anyone ever played that cruel joke on you by pulling a chair out from under you as you are about to sit down? You end up sprawled out on the floor because your feet were not under you as you were preparing to rest your weight on the chair. It is much the same as riding.
When a rider keeps their stirrups too low, they will have to continuously reach for them which causes the lower leg to slide forward in their attempt at doing so. The lower leg is no longer in the proper position when it is out in front of your body. You are not effectively balanced in the saddle anymore. By raising the stirrups you will not have to stretch you legs out to reach them, which will permit you to maintain proper lower leg position for good balance.
3. You will be able to get up on your seat bones.
I have no problem explaining to children where their seat bones are because they immediately start laughing whenever I say the word: "butt". For adults, it can be a little awkward! Don't sit on your butt like you do when you are seated in a chair. Sitting on your butt cheeks collapses your pelvic bone and often causes you to hunch your back. Proper riding position calls for a straight line from the shoulder, to the hip, down to the heel. This position is correct because you are keeping your center of balance over your horses center of balance. If anything is out of line your balance is thrown out of whack. Instead of sitting on your butt, you need to sit up on your seat bones (aka butt bones). Your seat bones are up underneath you. Sit on your hands and you will see that they are really up underneath your seat.
When you can't properly reach the stirrups, you have problems keeping your heels down and your legs slide forward causing you to sit back on your butt. When you sit back on your butt you aren't doing much by way of riding; just sitting on top the horse like a bag of bricks. Shorten your stirrups, and you will find it is much easier to get up off your butt and sit on your seat bones instead.
4. You will improve the posture of your back and upper body.
It's sort of a domino effect when a rider keeps his stirrups too long. It is difficult for the rider to reach his stirrups so he has difficulty keeping his heels down, which causes his legs to slide out in front of his body as he stretches to reach them, this in turn causes the rider to sit back on his butt, which causes his back and upper body to become rounded instead of straight. It starts at the bottom and effects every body part all the way to the top.
The back should be straight with the shoulders back, opening the chest. The lower back should absorb shock, but cannot be efficient in this job when slouched and hunched. Mama always got after you to sit up at the dinner table. I am sure you reluctantly slid back and straightened out your spine at her command. The same can be done by raising the stirrups and getting out of that lazy, chair sitting position.
It may be somewhat uncomfortable moving your stirrups up a few notches in the beginning. If you are too uncomfortable, just move up one hole at a time as you condition yourself and get used to shorter stirrups. Keep moving up until you reach the proper length.
A good way to judge how long your stirrups should be is by placing your finger tips at the very top of the fender on a Western saddle (get up under the flap) or at the stirrup bar on an English saddle. Grab the stirrup with your other hand and pull it up to your armpit. Using your arm you can measure the proper length. The stirrup should hit you just under your armpit. If the stirrup can extend past your armpit they are too long. Another way to judge is by sitting up in the saddle and letting your legs dangle loose over the stirrups. The bottom of the stirrup should hit you directly on your ankle bone. If it hits you anywhere lower than that, they are too long.
Once you get used to the new length you will find how much this simple change can improve your riding!