On One Pompino owners...

They are not the same hub shell spaced differently and are therefore not interchangeable: 120mm Surly New hubs: 42.5mm chainline 130mm Surly New hubs: 47.5mm chainline 135mm Surly New hubs: 53.5mm chainline (designed to run the ring on the outside tab of a 50mm chainline system, 50mm being the MTB standard) Where you place the ring on the crank (middle or outer position) and bottom bracket spindle length will affect your chainline, so eye it up.

From http://surlybikes.com/info_hole/