Roof mount cycle carriers

SteppenHerring Posts: 720
edited August 2009 in Road buying advice
Hi, has anyone got any opinions on roof mount cycle racks? Can I safely get all 4 of the family's bikes on there? (Including my new carbon pride and joy that I don't want to smash on the M4). I'm talking a range of tyre widths from mountain bike to 23mm and 24" diameter is the smallest wheel.

Obviously the thing being safe is important, but ease of use is a factor - although not much of one because my wife will claim she's not tall enough to put bikes up there.

Car is an Audi A4 saloon if that has an effect.