Back cinch

ive recently started using a back cinch as the back of my saddle has been bouncing. It definitely helps but it seems to be sliding forward toward the front cinch. Not sure what to do. I have it fitted correctly, about 2 finger of room, it’s not super loose. Any ideas?

First, you do have it properly hobbled to the front cinch, I assume?

It is normal for a flank cinch to go wherever it fits best, within the distance that hobble permits, hopefully not too long one.

What kind of riding are you doing?

Here is a video that shows how a flank cinch just hangs there:

https://www.youtube.com/watch?v=ppH8dQsySnM

For regular riding you want it one hole up.
There, hanging a bit low, you can see easily that it does move around a bit, some times forward, some back as far as the hobble permits.
I expect he has it extra loose there because he doesn’t want it to grab the horse’s belly when she really squats down while backing.

How much is your flank cinch moving around that it bothers you?

Somewhat depends on the conformation of the horse. One of my current horses, Dexter, is built a little downhill and has a rather large ribcage, so the back cinch tends to sit a bit more forward on him. It’s going to hang where it’s going to hang.

Now if the back of your saddle is bouncing up that much, I question how well your saddle fits in the first place. But that’s a different “issue” alltogether.