Adjustable dropouts, disc brakes and rear mount racks typically do not go together unless your bike is a Salsa, then your in luck because now Salsa has the Alternator Rack. The Alternator Rack is made specifically made for Salsa frames using the Alternator dropout system.
On bikes like the Salsa El Mariachi you will need to use a Salsa Rack-Lock seat collar which is not included with the rack. If your frame has upper seat stay mounts such as the Vaya Travel you will not need this collar. The Alternator Rack replaces the upper pivot bolt on the drop out system and does not work on other frames or dropout systems.
Tubular aluminum construction
27kg (59.5lbs) max load
Includes straight and bent extra long struts to make installation easier (for a rear rack anyways)
135 x 325mm deck that is cupped to better fit things like dry bags or sleeping gear.
I only purchased this rack because the alternator dropouts prevent the use of almost all other racks entirely. The rack is a sturdy setup for 30lb capacity given, more so than most other aluminum racks near $50. That said, this rack is still a little expensive for still being aluminum. Many Steel racks are actually lighter and more rigid, and I would gladly pay a little more for a stainless version. Some redesigned alternator dropouts with dedicated rack mounts should be introduced, that would increase capacity and give us the freedom to use Tubus (or equivalent) racks that are lighter and have a larger capacity.