Originally Posted by Trakhak

The common methods of spreading rear dropouts (or "fork ends," per Sheldon Brown's strongly expressed preference) were mentioned only once in this thread that I remember (those being the use of 2 x 4's, washers and nuts and a threaded rod. etc.).

Just dropping in to point out that, while the left and right dropouts often move equal distances from the frame's center line when a threaded rod is used, or when the mechanic just grabs and pulls the sides apart, equal movement is not guaranteed.

The advantage of the 2 x 4 method is that, if you begin with a frame whose alignment has been measured to be correct, you can bend one side at a time the correct distance. In the case of a 124-mm OLD being changed to 130 mm, that would be 3 mm per side, obviously.

Once you've moved each side 3 mm, all that's left to do is align the dropouts using the Campy H dropout tool or the Park equivalent and then reconfirm that the frame's alignment is still good.