jimboss wrote:What concerns are there with hanging bikes from the top tube?
Some bikes have unusual tube shapes that won't fit well, plenty have cables along the top tube and these can rub on the frame. I am not really keen on clamping to a painted surface due to the inherent rub, but do it when convenient or necessary. I just make sure that the bikes are tied down to prevent swaying.
I'm keen to get hold of an ISI or Gripsport rack that support by the wheels, but they are a lot more pricey than my current rear rack that is doing the job.