Leatt Brace fit

Can't really help you on the fit other than it may help to have someone there with you to help tweak it. Also, for dumbhilling I would slam the front/rear of the brace down as far as they'll go. Standing flat in the living room doesn't really recreate the extremes your head, neck and body will be while riding downhill. I found that if I didn't slam the forward (especially) and rear of the brace it severely limited how closely I could see the ground in front of me or the rear would cause the helmet to be pushed too far forward and I wasn't able to lift my head back enough to see out ahead of me.

Also, if you're not planning on cutting your jerseys to slip it under the chest/spine plates-use the straps! I went over the bars at Deer Valley and came straight down on my head-hard-and the straps kept the brace in place and I rode away without any injuries or soreness. Other than some pride left up in the dirt.

Remember: Don't be a fool. Straps are cool.

Adjust the rear plate, the thing that sticks down your spine, until the brace sits right on your shoulders such that there is equal pressure on the tops of your shoulders and onto your chest and back. You are going to have to push down on it just a bit to get the feel dialed. If when you push down the force is all on the tops of your shoulders and you can rock it back and forth, you need to shim the back plate tighter. This all depends on how thick your chest is. Then slam the platform all the way down in the back, otherwise you wont be able to look up high enough. I wouldn't worry about looking down low enough in the front, you should never be looking at the ground right in front of you anyway. I run mine sans straps, but they will keep it from jiggling around as much.