I really dislike buying shoes over the internet, they never fit properly and this was no exception. I Googled how 510's are sized, before I ordered them and most post's I found said they are sized about right for your normal shoe size. I ware a size 9 in most everything and have a fairly wide foot. I decided to order a 9.5  it was still way to narrow and no longer than a normal size 9 shoe. Should have ordered a 10. Hopefully they will stretch out a bit with use....