Thule Sidearm Universal Mount
Get maximum frame protection and quick loading/unloading with this upright roof-mounted bike carrier that only makes contact with your bikes wheels, never touching the frame.
I purchased a Thule sidearm because it was the only thing strong enough to secure my 50 pound downhill MTB. I carried that bike on the roof to Vermont, New Hampshire and Mass all the way to New Jersey, Virginia and Florida. After 4 years of use in all kinds of weather carrying various BMX, CX and XC bikes it is still holding strong. The only downside is the initial cost. I can say that it is worth it.
I have been using the Sidearm for just over a year, and has worked great! Can throw my 29er up on top of the car after a ride and don't have to take a wheel off or anything like that. There is a little rust starting on the ratchet buckle that clips over my rear wheel, but it seems to be superficial. This thing does exactly what it is supposed to, and I would buy it again.