What is UDH and is it the future of all bikes? SRAM's Universal Derailleur Hanger explained

If we were gambling types, we'd predict that UDH is an acronym cyclists will likely be hearing plenty more about in the next few years. It stands for Universal Derailleur Hanger, and promises a chance to "make shifting simple" with one rear mech hanger design that'll apparently make maintenance and shopping for replacements a breeze. Here's what we know so far... 

Invented by SRAM, the UDH is an admirable attempt to declutter the derailleur hanger market, an effort to standardise one single derailleur hanger design and thus eliminate the need for the hundreds of existing standards.

If you're not familiar with what your mech hanger does, it's a rather crucial piece of metal that attaches your rear derailleur to your bike frame's dropout, rather than the derailleur mounting directly to the frame like in days gone by. This means that if your derailleur does break off in a crash, you will most likely just write off the hanger rather than your entire frame. 

So financially, the pre-UDH mech hanger is an obvious winner... but if you've ever snapped or bent yours — only to begin the often frustrating and time-consuming mission of trying to work out exactly what replacement you'll need amid a sea of marginally different designs — you'll probably be quite relieved to hear all this about a universal solution.

> Is SRAM looking to kill the mech hanger?

The benefits are fairly obvious for us, the consumer. Mech hangers are very vulnerable to damage, it's a simple fact of crashes, spills and dropped bikes that a small replaceable hanger often won't survive bending or drive-side impacts.

That itself doesn't have to be a problem. We'd rather that than our frames taking more costly damage, but given the ease and frequency of such hanger-snapping mishaps, it makes sense to make the replacement process as easy, simple and cheap as possible, something that shopping a market filled with hundreds of existing standards can at times test the most patient pedaller. 

As the UDH product page states: "Today each bike brand designs their own hangers, and may have multiple incompatible hangers across their own models. Multiply this by hundreds of bike brands and you have a very big problem when a rider breaks their hanger and has to find a replacement. The UDH is meant to simplify this."

In theory, if all bike manufacturers ultimately moved to using UDH rather than their own designs, shopping for a replacement mech hanger would become a one-stop retail experience. Pay SRAM's recommended retail price of €18 (£15), or have a shop around to see if there are any cheaper, and fit your part.

Designed for use with thru-axles featuring a diameter of 12mm, it looks similar to other hangers, featuring the body of the hanger and a bolt that keeps it all tight in the dropout, a washer provided for use on some frames. The brand says it is designed to rotate rearwards in the event of impact, theoretically reducing the chances of bending or snapping.

SRAM also says its design means it has the ability to re-rail the chain back onto the small cog and prevents the chain coming off the cassette at the bottom end.

"It offers unparalleled derailleur protection. And perfect alignment. Guaranteed," SRAM claims.

However, the industry remains a decent way from the UDH utopia SRAM dreams of, and predictably there are still compatibility conundrums in the meantime, the hanger compatible with all Shimano's mountain bike groupsets, but being slightly more complicated when it comes to the components giant's road groupsets and those produced by Campagnolo.

Meeting the UDH with the 'Direct Mount' standard used by Shimano and Campagnolo requires use of a B-link, unless you want to purchase a UDH Direct Mount hanger, such as those from US-based Wheels Manufacturing, who have five more expensive hangers for offering "direct mount compatibility with Shimano rear derailleurs to any SRAM Universal Derailleur UDH compatible bike frame". Not exactly the universal single part to make derailleur hanger shopping child's play.

With all that said, the list of bikes using the UDH is ever-growing, SRAM's bike finder compatibility page currently suggesting that 65 models, including 17 road bikes now have it. Trek's latest editions of the Madone, as well as selected bikes from Cervélo, Ridley, Cipollini, Lauf and 3T.

On the gravel side of things, there are even more, with big-name brands such as Specialized, Canyon and BMC all using the tech. Earlier in the summer, we reported that Specialized's new S-Works Crux gravel bike had been updated with UDH compatibility.

Increased standardisation across bikes and brands has been wanted by many for a long time now, the wide range of types, sizes, standards, widths etc. across some parts seen as frustrating and puzzling, even for seasoned home mechanics, and outright baffling for newer riders. 

One such standardisation example is Shimano's move towards Cues, offering riders new cross-compatible groupsets for city, touring and mountain bikes, the aim to eventually consolidate its lower-end Claris, Sora and Tiagra groupsets under one roof

Last year we saw a new 9,10 and 11-speed, disc-brake-only drivetrain ecosystem announced, meaning everything below mechanical 105 will be slowly phased out on flat bar bikes, with the likelihood that these changes would be coming to drop bar bikes too in the not too distant future.

> Chapeau, Shimano: CUES looks like a genuine game changer for bike shops, brands and consumers

More recently a new drop-bar groupset was seen on the Cube Nuroad Pro gravel bike, likely slotting in between the more premium GRX offering and budget road bike groupsets, Shimano telling us "more information will be shared in early 2025".