I bought one for my single bikes a while back and returned it a couple days later. Wasn't really impressed with the build quality. As for putting a tandem on the back ... only if it doesn't stick out past the sides of the vehicle, you lock the handlebars straight with a strap of some sort, and you don't plan to put another bike on at the same time. They are only designed to carry so much weight, but a single tandem weight should be fine. My 2-cents.