Specialized Lightweight UDH Derailleur Hanger

The UDH standard was supposed to end the hunt for frame-specific hangers, and mostly it has — but Specialized builds a road-specific take on it. The Lightweight UDH Derailleur Hanger is a pared-down version of SRAM's bolt-on Universal Derailleur Hanger, reshaped for the cleaner lines of a road dropout and fitted from the factory on Tarmac SL9, Crux 5, and Aethos 2 frames. Same interface the rest of the UDH world uses, with less material wrapped around it.

That factory-fit detail matters more than it sounds. This is the replacement for bikes and framesets that left the factory with this exact hanger, not a drop-in swap for every UDH frame on the market. If your frame shipped with the standard full-size UDH, keep running that one. If your Tarmac SL9, Crux 5, or Aethos 2 came with the lightweight hanger, this is the matching part, and keeping the hanger consistent with what the frame was designed around keeps derailleur alignment and tire clearance where they started.

Two things catch people out during installation. The mounting bolt is left-hand (reverse) thread, so it loosens in the opposite direction from what your hands expect — forcing it the usual way is how hangers get rounded out in a driveway before a ride. The hanger also requires a thru-axle with a 1.0mm thread pitch, which is what the compatible frames use. The SRAM UDH bolt and washer are included, so you are not reusing hardware that took the same hit as the old hanger.... Read More