I've never found it to be a big deal. The horses learn how to use them pretty quick.  I see my horses clamping their tails down on the crupper when the saddles start to move.  They've learned to use them when they need them.

As mentioned above a little work in a round pen and they quickly get used to them. It's not a long learning curve.

The biggest caution is to no over tighten them.  You don't want the horse being squeezed between a crupper and the breast collar during normal movement. Or having it so tight that it incourages an inverted or hollow back.  You want them somewhat loose on the flat and when they start down hill the horses will clamp down their tail and tighten them.

No rule of thumb.  Just look at it and make sure it has some slack when the horse is standing normal. 

When a horse starts downhill, They collect up and round out their backs,  This rounding out will take out most of the slack and as I mention your horse will quickly learn to clamp down their tail to really tight up the crupper.  You are not trying to pull the saddle backwards.  Just prevent it from sliding forward.

I tried to find some photos that show the cruppers.  But I couldn't find any that clearly show it.

This photo, has the horses head downhill, so he is already kinda rounded out and his tail is clamped down, You can see that most of the slack is gone.

Another lousy photo. The cantle bag is covering most of the crupper.

This is a really steep downhill. These horses all have cruppers on, But you can kinda see them on the palominos. But all the horses have their tails clamped down on the Cruppers, except for the lead horse that has turned across the face of the hill and lifted his tail.

The kid on the palomino here is using an australian saddle that doesn't have a D ring for the crupper, So this crupper splits and buckles to the two side rings.

If you've ponyed extra horses or lead pack horses much with your horses, They will get the lead rope under their tail. This is much the same sensation to the horse.   Once they've learned not to worry about a rope under their tail, a crupper is no big deal.

To start teaching them, I often just put the lead rope under their tail. You can pull it out quick or let the horse lift his tail to drop it. So no need for the rodeos with a crupper that you can't reach to unbuckle.

Cool pics, PH..........you folks probably wouldn't know what to do with flat land!!! Beautiful territory out there. Have been riding in Montana and hope to get out to your area some day.

Wish me luck.....hope this , with some patience and going easy, will not be too much of an event. I appreciate eveyone's advice and good stories. I know all about those things that weren't too great when they happened, but make great campfire chat now!! Of course, when everyone gets through embellishing the story....it's much, much better! Happy trails, everyone.

Glad it worked out for you.  I've never found it very difficult to teach horse to use a crupper.

I spent a year in SC and a year in GA, So I do understand your flat tree covered country. Seemed the only time I could see the sun set was if the road I was on headed due west. Other wize, the sun just went behind the tops of the trees.

These are actually sunrises, But you get the idea of seeing the sun move behind the actual land mass.

Established Trails?   Unlike the eastern part of the country, The mountain west is mostly public lands. Forest Service, BLM, State Trust Lands.  So we don't have established horse camps like the eastern part of the country has.  Virtually all of my camping is primative camping.

As far as trails.  We ride some marked Forest Service trails. usually during the summer months. Fall hunting season, we just wander the mountains as we hunt for elk or deer.  Most spring rides are on BLM land, and there are not many "Marked Trails" there. It's just wandering the desert.

Rides in Slot canyons are pretty defined by the canyon walls.  We just ride up the washed out stream beds.

Some rides we just follow the game trails or the cow trails or just wander our way to the ridge top

Some rides are trails that have been used since before white men came west. Indian traveled and traded over the Great Western Trail for example. The Forest Service and private groups like Back Country Horsemen maintain some of these trails.