Disc Brake Retrofits
From Pvdwiki
Slotted Dropouts
Kirk Pacenti sells some nice tabs that can be welded to old single speed frames to get them up to speed with disc brakes. I wish that the lower tab was longer. It was very difficult to preserve the usefulness of the slots in this application. I lost 1/3 of the slot range.
Don't forget to add a little support to the seatstay when mounting the tab directly to it.