What is UDH you may wonder? UDH is Universal Derailleur Hanger.
This standard was developed by SRAM and has been around for a few years, and was originally intended for mountain bikes. However, UDH has slowly been making its way to road and gravel bikes.
What’s it all about, is it just for SRAM? Answers in the video below!
UDH Gravel Bikes Video
Alternative Video Link for those reading via email subscription
In this video, JOM of the Gravel Cyclist crew breaks down some of the mystery of UDH, known compatibility issues, and solutions.
UDH on Gravel Bikes Explained (or see video)
If you look at just about 99.99% of bicycles out there with a replaceable derailleur hanger, you’ll know that each hanger is unique to just about every frame. Clearly that represents a problem if you drop the bike, crash the bike, have the derailleur torn off the bike by mud, sticks, anything really. By the way, a no cost plug to Wheels Manufacturing, they are likely to have the derailleur hanger you are looking for in their vast stock.
Continuing forward with UDH, the concept is SRAM’s idea of utilizing a single derailleur hanger, one to end them all, but it does require a physical change to the frame’s design to accommodate it. Thus, manufacturers need to be on board. It’s a big ask for certain.
Another advantage according to SRAM, is a measure of crash proofing, if that’s possible. The UDH hanger design allows the hanger to shift backwards slightly under impact. You can also see here the unique design of this SRAM Red 13 speed derailleur, which essentially adopts SRAM’s Transmission aka T-Type rear MTB derailleur design, to ditch the derailleur hanger altogether.
Pictured on these gravel bikes by No. 22 Bicycles (above) and Officina Battaglin (below), you can see this system at play, which also eliminates limit screws and the B-screw from this derailleur design.
The UDH design also improves alignment of the derailleur relative to the cassette, meaning no more bent or misaligned hangers, and no more fidgeting with bending your traditional derailleur hanger back into alignment. I have an entire video dedicated to hanger alignment.
Because UDH is designed for SRAM transmissions unless you use an adapter (more on that in a moment), the special frame dropout and derailleur, cause some compatibility issues.
Stating the obvious, UDH causes issues with derailleurs not designed for this system, such as SRAM’s own 11/12 speed mechanical and eTap rear derailleurs, most any other type of derailleur produced in the past 30 or so years, and in the case of Shimano’s latest derailleurs, the Shimano Direct Mount system. Campagnolo is another company utilizing the direct mount system.
But, it’s not all bad news! There are various adapters to bring compatibility between UDH derailleurs and most every other derailleur, once again thanks to Wheels Manufacturing. I swear, they are not paying me to write this article, or produce the video above. More than anything, this is a Public Service Announcement.
To date, the UDH standard has been slated exclusive for 1x drivetrains, but I expect we could see 2x offered, depending on manufacturer reception to the concept. It will be interesting to see how UDH plays out over next couple of years.
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Links of Interest:
- Wheels Manufacturing Website
- SRAM Red XPLR AXS 13 Speed Build Party with No. 22 Drifter Adventure
- Officina Battaglin Pave’ Review
- Framework Bicycles Review: Insane Precision
- Stinner Carrizo Select Bike Review
- Trek Checkpoint SL Generation 3 Review
- ENVE Fray Review on EVERY Road
- Brickyard Bike Co. Website
- North Florida Freeride Gravel Series
- How to Create Amazing & Fun Gravel Routes!
- Gravel Cyclist’s Route Library
- Gravel Bike Tire / Tyre Pressure Recommendations
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