What do Quarter Horse, Semi-Quarter Horse and Full Quarter Horse bars mean?
Actually, nothing really that specific... While there was a good reason they were initially used, things have changed over the years so now they are very general terms only. So unless you are comparing trees made from the same tree maker, not just the same saddle maker (and very often in production saddles you don't know who built the tree), they really can't even be used in a comparative way any more.
What are bars?
OK, while this is a basic question for a blog supposedly aimed at saddle makers, it is one I have seen not uncommonly on equine forums. I have also seen "interesting" answers to it. The bars are the two pieces of the tree that go on the horse's back. They are what need to fit the shape of the back - in length, spread, angle, twist, rock, crown, etc. - all the things discussed in our Factors that Affect Fit page.
The terms Quarter Horse bars, Semi-Quarter Horse bars and Full Quarter Horse bars aren't really talking about the bars - just to confuse you. They are terms that were originally meant to describe a fit - the way these bars were set and shaped to fit a certain style of horse.
Where they started
From what we understand from a saddle maker who knows the history, back somewhere around the middle of the last century a major saddle company wanted to help its customers get the right fit for their horses. Most of their saddles were built to fit the average, common horse that was around back then - and there was a lot less variation 50 - 60 years ago than there is now in the general population of horses. Those horses were much narrower and more A shaped than our average, common quarter horse in North America today. And these ended up being the "Regular bars" fit.
Quarter Horse Bars
But then the Quarter Horse influence started growing, and there were a lot more muscular, wider horses around. So they came up with what they called their "Quarter Horse bars" fit. In these trees, the bars were spread farther apart from each other, and they were set at a flatter angle compared to each other.
Semi-Quarter Horse Bars
This worked fine, except there were horses that fell between these two fits, so the Quarter Horse bars fit was too wide and flat and the Regular bars fit was too narrow and steep angled. So, the company came out with Semi-Quarter Horse bars. The bars themselves were set at a middle of the road width and the angle of the bars was set between the Regular and Quarter Horse bars angles.
Full Quarter Horse Bars
Then, as time went on and horses got bigger and the real bulldog type Quarter Horses had more influence, there were getting to be a larger number of horses that were too wide even for the Quarter Horse bars fit. So they came out with the Full Quarter Horse bars fit - with the bar spread even wider and the bar angle even flatter.
It's a progression
So the different fits went in a sequence from Regular, to Semi-Quarter Horse to Quarter Horse to Full Quarter Horse with the bars progressively getting farther apart and angles progressively getting wider. So far so good. At least you would have an idea of where in the range of "typical horse sizes" your horse was and you could, from this company, order something that you would hope would fit that section of the range.
What about the other factors that affect fit?
I expect that the original company who used these terms didn't just change the width and angle, but they also would have incorporated different twists, crown patterns, etc. into their "bars sizes", but I don't know that for sure. And there were never any measurements or terms given to these different factors, at least not that anyone outside the company would have known.
But - every tree maker does things differently...
So what happened was that other companies thought this was a good idea, and since the terms were catching on, they used the same terms. Problem was, they used different trees from different tree makers, and those trees would have fit horses differently. People really in the know would have understood that Company A's original bars would have fit a horse like this and Company B's original bars would have fit a horse like that. And when Company B decided to make Quarter Horse bars, they would have fit a horse differently than Company A's Quarter Horse bars. But pretty soon people who didn't understand that every tree maker (and every saddle maker) does things differently were figuring that since the terms were the same, the fit was the same.
Well, it wasn't true then and it isn't true now. There are no standards for what a Semi-Quarter Horse bars saddle fits like. And while within one tree maker, the progression from Regular to Semi-Quarter Horse to Quarter Horse to Full Quarter Horse still goes from narrowest to widest, it doesn't necessarily mean it is the same between makers. One maker's Semi-Quarter Horse bars could be wider in spread and/or angle than another maker's Quarter Horse bars. And how either maker's bars actually fit the horse - well there is no way of knowing that other than putting it on the horse and, very often, going for a ride.
While the Semi-Quarter Horse, Quarter Horse and Full Quarter Horse designations may give you a bit of an idea of the section of the bell curve of horse's back shapes that the saddle is supposed to fit, in reality fitting a saddle to a horse is like buying women's clothing. It doesn't matter what the label says - you gotta try it on!
So unless you have enough money for a custom saddle (and a lovely custom tree like you guys build!) buying saddles is really trial and error. Expensive trial and error at that.
The only good thing about it is if you find a brand of tree that fits your horse(s) best, then you know you can search for that same brand of saddle tree next time you buy a saddle and have an idea of how their bars fit. I have done that. There is a particular brand of factory saddle tree that I have had good luck with and now I search for saddles with that particular brand of tree. Other trees (like Ralide in particular) never seem to fit my horses well.
If I ever come into fortune I would love to have a custom saddle with a tree made by you guys.
Until then, I love reading and learning from your blog. :)