JMS, I have a sneaking suspicion from your description that you might not have been attaching the holdback straps to the right thing. Did you run them up to the tug loops themselves initially? If so, no wonder they didn't work well and he was having trouble!
If you're using a standard show cart there may not even be any footman's loops, which are the metal brackets on the underside of the shafts the breeching is meant to be run through. They give the holdback straps a solid purchase on the cart so the shafts can't slip forward through the leather wraps; if you don't have them, you'll need to install them. You can temporarily use the leather trace carrier loops that are riveted onto the shafts to anchor your breeching but they aren't meant to take much stress and should only be used as "slightly better than nothing."
Here's a picture of my breeching on the Hyperbike. You've got the two hipstraps coming down, the breeching itself going around the rear, a trace carrier (something you don't need) hanging down from the breeching ring, then the holdback strap going forward and wrapping around the shaft. On a normal cart where the trace is running horizontally I take the holdback forward under the trace, run it through the footman's loop on the underside of the shaft, wrap it two or three times (whichever is appropriate) from outside to inside around the shaft, then pass it back OVER the shaft and trace and buckle it in. Before buckling it, pass the end of the strap through the last of the loops (the one closest to the buckle) to help snug it down. This way if the leather should give at the buckle the holdback will have a sort of knot around the shaft that may hopefully hold until you can get the horse stopped.
The breeching itself should sit about midway up the curve of the rump- low enough that it won't ride up but high enough that it won't take the horse's legs out from under him. Usually with full-sized horses we say about the height of the stifle joint but I find with minis and our relatively taller carts it's usually above that point.
New mini said:
Since you say that the closed fist is going to be to loose on a mini can you give me an idea of what might be the correct distance?
I use about three fingers, give or take. You need it to be tight enough that the shaft tip doesn't swing forward past the point of the shoulder but not so tight that it restricts the horse when he moves out and every horse is going to be a little different as to what that measurement is.
susanne said:
Be certain that you hitch on as level of ground as possible. Otherwise, the cart will roll forward or backward; either way and your breeching will end up too loose or too tight when in draft. You want the cart to be in "neutral," not "drive" or "reverse!"
Everyone does things differently- I like to hitch on a slight upslope so the traces are tight and I can adjust the breeching correctly right from the start. If the horse is on a completely level surface there's often more "slop" and it's hard to tell at first if you've got both ends right on a first hitch. Both methods work and have their advantages.
Leia