I've had my Big Mouths for about a year and I've come to pretty much love them. For starters, they are incredibly easy to install and even easier to put to use. I can get two bikes in their trays in under two minutes. I drive a Pontiac Vibe so it's a little taller than most cars but this rack is still a breeze. There are a couple of tricks that I've learned though. First, place the mouth in a vertical position that way you can plop your bike into the jaws right away. This will help hold your bike upright while you work your fat mtn. tires in the trays. Secondly, if you want to really secure your ride, before you close the jaws, reach up and squeeze the jaws around your frame and simultaneously close the lever. This will increase the pressure on the frame and to this day, I've never had any problems with the arm slipping on either my mountain bike or my roadie. Another little thing I've learned is that you can use the tire straps like a winch to really wedge your tires into the tray. There is a bit of sway when cornering or going over bumps but I've never been worried about the bikes coming off. Other than the increased wind noise, gas mileage takes a slight hit, even with two bikes up there. All in all, I'd be likely to buy this rack system again and I'd definitely recommend them to a friend but if you're looking for a rack that holds your bike completely secure, take a look at fork mount racks.