Are you sure you are a 52 frame? You want to be very careful to get the right size and a good fit. For your first bike, it might be wise to buy from a store, whether it's used or not. Hopefully a store you have been referred to and feel you can trust. Not all bike shops are the same in this regard. If you are 100% sure what your frame size is and, especially if you have someone helping you who knows a thing or two about bikes, then you might be fine buying online. But either way, get a bike fit at a shop.