First of all I did search google, but found mainly products not answers (crc sucks at spec details). I am pretty sure that euro is 68mm english threads, but I just wanted a second opinion before I had two frames made with the wrong type of bb. As for it being the size of bearing that is not quite true. There are many types of bmx bb (usa, spanish, mid, euro) and they all use the same two inner diameter of bearing i.e. either 19mm or 21mm (I think). The type of BB refers to not just the outer beaing diameter, but also bb width and installation style, e.g. press fit, standard thread or reverse thread. I know I pretty much answered my own question, I just wanted to check with other people before marino builds my frames.