Understanding UDH and Full Mount

The Universal Derailleur Hanger and Full Mount technology both help deliver simpler, higher-performing drivetrains. We’re here to explain how these derailleur mounting styles work so you can confidently navigate identifying what’s on your bike, which parts are compatible, and why these technologies make your ride better. Let’s set the hanger record straight and answer some common questions about UDH and Full Mount.

What’s the difference between UDH and Full Mount?

What’s the history behind Universal Derailleur Hangers?

The beginning

You’ve probably broken a derailleur hanger or two in your day since it’s essentially been the sacrificial bodyguard of your drivetrain. The bike shop visit of the past would typically include a hanger special order, leaving your poor bike behind, and waiting for your frame manufacturer to send the specific hanger for your specific frame. We at SRAM decided to work towards a more sensible solution for replacing damaged hangers and introduced the Universal Derailleur Hanger, or UDH, in 2019.

The why

The UDH consolidates endless hanger options and has been widely adopted throughout the cycling industry with thousands of frames featuring it on both flat bar and drop bar models. Frame manufacturers that design their bikes around this standard ensure a better and more consistent shift experience for all drivetrains because the fixed position of the derailleur is standardized with a UDH. Plus, it protects your derailleur with slight rotation during impact.

The future

Improved drivetrain performance, guaranteed better alignment, and compatibility with all drivetrains? UDH can do it all...and more. UDH also laid the foundation for Full Mount by creating a standardized mounting interface on frames. Utilizing the larger diameter of the UDH interface, Eagle Transmission and RED XPLR AXS derailleurs mount to frames with a super strong, super simple Full Mount design. These derailleurs clamp around both sides of the frame itself and eliminate the need for a hanger. This sturdy connection removes variance and improper adjustment across frame designs, while also allowing the derailleur to rotate backward during impact without the risk of a hanger failure. All this Full Mount goodness became available to riders in 2023 thanks to the UDH interface paving the way for the future.

Does my bike have Universal Derailleur Hanger?

Whether you ride MTB, gravel, or road, you can determine if you have a UDH on your bike in three simple steps.

Where can I get a spare UDH?

Anywhere! Universal Derailleur Hangers are available at SRAM dealers globally, so your search for a spare is likely to be as smooth as your shifting with a fresh hanger.

Find a SRAM dealer

Will a Full Mount derailleur work on my bike?

Full Mount derailleurs mount to frames that use the UDH interface. If you have Universal Derailleur Hanger, your bike is ready for any of SRAM’s Full Mount derailleurs, including Eagle Transmission and RED XPLR AXS. Full Mount derailleurs work around the center of the rear axle, which is a universal constant for all drivetrains. This opens the possibility for perfect shifting, eliminates unnecessary adjustment screws, and allows for the most robust and precise drivetrain possible for MTB or road and gravel applications.

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UNDERSTANDING UDH AND FULL MOUNT

What’s the difference between UDH and Full Mount?