Derailleur Hanger Sram UDHDerailleur Hanger Sram UDH The hardest working derailleur hanger The UDH is designed to optimize shift performance across all bikes as well as create a sensible solution for replacing damaged hangers. The UDH has been widely adopted throughout the cycling industry with hundreds of models already featuring it. Making your shifting simple By standardizing the fixed position of the derailleur, the UDH creates a better and more consistent shift experience