| ebay bikes are not that bad. if you know what you are doing, they are easy to setup, and last if you look after them. they are the exact same bikes you get from reputable dealers. the only difference is that the reputable dealers setup the bike, and adjust everything so they dont **** up. you can do this with a bike from ebay.
you can bring a bike back to a reputable dealer to fix under warranty though, which is a bonus if you dont know what you are doing | 
