old thread but worth contributing. like
#2 wrote, you can put 2 on the hitch & the other 2 on something else. my Subaru Forester had a Class I hitch. I tried 4 bikes but it was nutz. I did a test ride out of our condo complex & heard some really weird sounds that were just not right, as I went over the speed bumps. wound up using an SUV rack I had. the kind that rests on the rear bumper, in addition to the hitch rack
not acceptable
acceptable
I've since upgraded to a vehicle with a class II hitch (& a beefier rear suspension). I also use 3 stabilizer straps so there is ZERO bounce, rattle or sway
