If you are only going to be carrying 1 bike 99% of the time look at a 1upusa rack. Their racks are expensive but if you only need a single for now it isn't that expensive and the single takes up very little room when folded up. Plus it is all aluminum so you don't have to worry about it rusting after a few years if you leave it on all the time like I do. The swagarms and clones work fine but any rack that touches the frame will scratch up your bike's paint over time if you care, I don't.