thats excellent advise for a beginner, but a bit over the top as general advise without a qualification... I've bought plenty of used bikes, even built up used bikes bought just as frames that I've turned into custom things to suit my own tastes... but I've been riding bikes since the late 1960s. Even if I buy a new bike, I'm out there playing with the stem lengths, swapping bars, oedals, etc etc til I get it right where I want it.