I carry my non suspension Gary Fisher mountain bike on an old Thule trunk mount that I reconditioned and haven't had any problems. It has a four bike capacity, but I'd never try that many more than a couple miles. The newer models are much more robust, but I still would be nervous with more than two on a trunk mount. And even with one bike I use two or three bungee cords and a styrofoam block on the inside pedal. My son owns a bike shop and he only uses a hitch mount. U-Haul is best for getting a hitch installed, but then we're over $200 all inclusive. Previously he used a roof mount and traveled the east coast with it. Back to trunk mounts there a lot of cheap junk out there, I'd stick with name brands like Thule.