Originally Posted by crazybrit
Bentspoke. And this spec (for the 5205-2RS) is functionally the same as the Euro 3205.B.2RSR. I believe I'm correct on the 'B' designation being the standard/default and therefore not particularly important.
My book shows a A as a Conrad in the 500 series, so that would mean default.
The B is listed as 40deg contact angle. It looks like the A's have a 30 deg contact angle. They may only make most of them one way or the other so those internal dimensions probably do not matter on the user end.
Many comapanies drop or change the first digit, adopting the somewhat universal series number of the second, and bore code of the last 2.
Multiply the last 2 digits times 5, that gives you the bore. That X5 formula works for most bearings in the 5000 and 6000 series. 6003 and below it does not apply.