Roof racks are bad in two situations:
1. You have a wife who wants to load/unload bikes without you
2. You forget you have it loaded when you drive in the garage. Friend of mine did this.
I have a hitch rack. I've had two types, and was told that
this type would not work for carbon fiber bikes. Maybe someone else could tell me if that is true or not?
Now I have
one of these - works great for any type of bike. The first one only worked for ones that have certain body types. Didn't work well for cruisers, mountain bikes with suspension, etc.