This seems like such a great idea. Maybe too good to be true.
Well, I purchased the ass saver and gave it a shot. But during my first ride with the ass saver I lost the fender.
I suspect that the fender secures more strongly to certain bikes over others.
I would suggest looking to a slightly more expensive fender which securely attaches to the seat post.
Just to describe the ride I was on. I was on a training ride on a bike path on a fairly windy day. So I suspect my speed and crosswinds were too much for the ass saver.
Unlike some other riders, I love the Ass Saver! It's lightweight, easy to put on, easy to carry. And cheap. It does a decent job of keeping your rear dry, and saves you the hassle of putting on full fenders. Your riding mates might get sprayed if they ride too close, but they'll figure it out.
This product won't keep you 100% dry, as full fenders would, but that's not the purpose of it. It's an ass-saver for a reason. Construction seems sturdy. It doesn't take up much room as it can fold under your seat when not in use.
This thing works great!!! It keeps the spray and mud from your rear tire off of your butt and back. It's super light and is easy to install. I put it on when the streets are wet or I know it's going to rain.