Let's do the twist!
We are no longer building saddle trees. We have two saddle fit videos available on our westernsaddlefit.com website. Western Saddle Fit - The Basics, aimed at riders, is available either on DVD or streaming on Vimeo while the six hour series Well Beyond the Basics, aimed more for professionals but understandable by anyone, is available by streaming on Vimeo. (We left this website up because we have had many requests to keep the information available.)
One of the Factors that Affect Fit that we haven't discussed yet on our blog is the amount of twist in the bar. Because horse's backs are not even from front to back, but steeper at the withers and flatter over the loin, the bar must change "angle" along its length to match the shape of the horse. This is called "twist". No, the wood isn't twisted to make this shape - the shape is carved from a flat piece of wood. But as you look down the bar, you can see the "twist" in the angle from front to back.
Just to clarify off the top, the definition above is for Western saddles. English saddles have an entirely different definition of "twist" and there can be a lot of confusion if people don't know this. The twist in an English saddle is the narrowest section of the seat, where the angle of the seat is more upright compared to the flatter seat farther back. We had a phone call last week from a woman who has ridden English most of her life but is now trying out western saddles. She had contacted a couple of saddle makers asking about getting a saddle with a "narrow twist". Both had told her she needed to talk to a tree maker to get that. Since I know both definitions, I was initially confused as it is the saddle maker who builds in the seat shape - until I figured out that neither she, nor probably the saddle makers, recognised that the definition is different between English and western saddles. Communication isn't always easy...
Does twist vary?
When we first started building trees (and writing information articles) we said that twist rarely needed to be changed in a tree as horses were pretty similar in this way. And for the horses we were building for and the market we were serving at that time, this was true. A lot of our trees were going to working cowboys in the Canadian west and the northwest US, and these horses tended to have very similar conformation and back shapes. Even with the slight variation in size, the twist was pretty consistent.
However, now that our market and our experience with other types of horses has expanded, we have learned that there is more of a variation in twist than we originally had seen. One of the things that really showed us this was the Dennis Lane Equine Back Profiling System. (I know I keep mentioning this, but we really have learned a lot by using it and have found it very useful in communicating back shapes between our clients and us.) Having an objective standard to compare to horses to also makes it very easy to compare between horses.
How the Dennis Lane system shows twist
When Dennis first made up his system, he numbered the cards based on the common correlations he saw. So if the card at the A position (right behind the shoulder blade) was, for example, the D4 size, then the cards at B (lowest point of the back behind the withers) and C (eight inches back of B) were most commonly D4 as well. When he came over to North America, he found that with a D4 at A, the B and C cards were often much wider - even wider than his system originally allowed for. (He has since added wider cards.) What was the difference?
The difference was that North American quarter horses are much broader at the loin, even with the same shape or "angle" of the withers, compared to the much more Thoroughbred influenced horses in Australia. In other words, the amount of twist is different, and the different combination of cards that fit the horses showed the difference. Here's some pictures of what we mean.
Although not the best example due to winter hair and uneven posture, this picture shows a typical back for a western Canadian ranch horse - moderate steepness to the withers and widening out over the loin. For this shape we use a 4" hand hole width, 90 degree bar angle, our normal rock (R6 on the DL numbers) and our normal amount of twist. This is the body type our original patterns were designed to fit and it is still a very common body type we build for.
This is a different body type. The shape at the withers is the same (both horses were S7 at A on the DL system), but you can see the difference in the "angle" of the loin. The ranch horse is flatter compared to how steep this horse is. This horse also got a tree with a 4" hand hole and 90 degree bar angle. However, if we had used our normal amount of twist, the inner part of the bars over the loin would be carrying more of the weight while the bottom edge would be lifted off the horse. So this is a body type where we need to decrease the twist from our "normal".
Twist and breeds?
Looking at what we know now, we have come to a few willing-to-have-our-minds-changed assumptions, or maybe I should just call them "leanings" at this point in time. I wonder if what we see as "normal" here in North America may actually be outside the norm if you look at the whole population of horses in the world and over time. North American quarter horses in general seem to have a lot more twist in their backs than a lot of other types of horses - thoroughbreds, some gaited horses, mules, etc. (But we always caution that you shouldn't fit a horse based on his breed as there is often more variation within a breed than between breeds.) Or maybe it isn't so much breed as areas of the world. In Australia, since the average horses Dennis sees have much less twist in their back than North American horses do, he has to change his "normal" twist when he builds a tree for over here.
Here is another example of where we need to adjust the twist. This horse has very wide withers, so the bar angle needs to be much flatter than for our "typical ranch horse". However, the measurement at the loin is still the same as the "typical ranch horse". When we tilt the bars out more to flatten the angle to match the wither shape, the same thing happens at the back of the bars as to the front - the angle is flattened. This makes it too flat at the back so, as in the example above, the inside takes more weight while the outside lifts off the horse. Therefore, for this body type we again need to decrease the twist from our "normal" to make the "angle" at the back of the bars fit the loin. (This is a good demonstration of how fit is all about shape, not just a measurement or two...)
So do all our bars have different twist?
No. We have our "normal" twist which is what we use on most of the orders for the common types of horses we build for. But now we also have a few variations based on what we have been learning about twist over the past few years. This is still a work in progress, because there is always more to learn!!
How important is twist?
While getting the shapes to match as much as possible is always the goal, if you were going to rank the factors that affect fit according to importance, we think twist would be lower on the list. Getting the hand hole width and angle correct to match the wither area is really important as there is more constant pressure there. You have a bit more leeway as far as getting the angle correct along the rest of the bar (unless, of course, you have a lot less twist than needed so that the bottom of the bars end up Poking the horse). This is for a couple of reasons. One is that there is more movement and therefore much more variation in pressure under the back of the bars. The other is that because the horse's back is flatter at the back of the bar, a difference in "angle" towards the loin doesn't change the weight bearing areas as much as where the "angle" is steeper up front.
So when you are evaluating a tree or a saddle for fit, you need to remember to check not only the front of the bars
but the back and the middle as well to see how ideal the twist is for the horse.
Now, as to the middle and where the "twist" happens, that will have to be another post - sometime...