Replaceable derailleur hangers have outstayed their welcome and I don’t want to see one on a new bike ever again.
Having just tested SRAM’s new Red XPLR AXS groupset – which has adopted the American brand’s Universal Derailleur Hanger standard – the shortcomings of traditional, replaceable derailleur hangers have never felt clearer.
While cyclists often groan at the introduction of new ‘standards’, UDH delivers on its promises – chiefly improved robustness, simpler replacements and, above all, more accurate and reliable shifting.
What’s more, it does all this with no discernable downsides (save from the fact it's not possible to retro-fit UDH onto most existing bikes).
So, what are we waiting for? It’s time to consign replaceable derailleur hangers to Room 101 and make UDH the future of cycling.
Replaceable hangers were a good fix at the time, but we need to move on
Back in the heady days of the 1980s and early 90s when I first started to own ‘proper’ performance road bikes, the king of the hill was still steel.
As many will know, steel is a great material for bike frames and derailleur hangers. It’s ‘real’, which always helps, but it’s also tough, and it can take a knock or two.
Should the hanger portion of your steel frame ever get bumped off line, some gentle persuasion can often put things right.
Should the worst happen and things go catastrophically wrong, steel can also be repaired, and bent or broken dropouts replaced.
When aluminium came along, and then shortly after carbon fibre, things got complicated. Both aluminium and carbon are tricky to fix – and they’re expensive. Thus, the sacrificial replaceable derailleur hanger was born.
If you stacked your bike, these fragile little parts were designed to fail, (hopefully) leaving your expensive frame and derailleur intact.
That’s all well and good, but it was another bolt-on part that introduced a level of inconsistency that doesn’t gel with the fine margins of setup demanded by modern drivetrains.
Back in the early days of replaceable hangers, we were dealing with 8- and 9-speed drivetrains, with far greater margin for setup error or hanger alignment issues than modern 11-, 12- or 13-speed systems.
As freehub widths have largely remained constant, this ever-increasing number of gears has meant sprockets and chains have got progressively narrower, meaning the tolerance for poor setup or an even slightly bent hanger is tiny.
No matter how expensive your frame or groupset, no bike is safe from the woes of a bent derailleur hanger.
Even something as simple as a touch too much paint on the interface can throw a replaceable hanger out of alignment.
What’s worse, practically every frame has its own unique derailleur hanger design. As with bottom brackets, there’s no one-size-fits-all hanger that you can find in every bike shop.
If your hanger gets bent during transport on your way to that cycling holiday of a lifetime, the chances of being able to get a replacement at your destination are slim.
Ask yourself this: if you needed a new hanger, would you know what to look for and how to get hold of it?
UDH is a new standard, but it should be the only standard
I know many cyclists have had their fingers burned by magical new bike ‘standards’ that have promised to solve all problems and offer nothing but good times, but UDH isn’t one of those.
In essence, UDH is simple – it isn’t a new derailleur hanger at all, it’s a round hole in the driveside dropout.
Even the laziest frame manufacturers should be able to make a horizontal axle across the rear end of a frame, plus there are no unique parts and nothing to bolt onto the frame that could introduce variances in dimensions.
Likewise, if you want to run existing rear derailleurs (which don’t all feature direct-mount designs), a threaded insert with a traditional-style hanger is already available – as seen on the Santa Cruz Stigmata and eighth-generation Trek Madone SLR.
Best of all, UDH isn’t frame-specific. As long as the dropouts are right, the same UDH hanger that fits a burly electric mountain bike can fit a featherweight road bike.
For shops, this means carrying a single type of hanger to serve all customers with UDH-compatible bikes. For riders of such bikes, it means a vastly increased chance of being able to source a replacement in an emergency.
Why has uptake of UDH been so slow on road and gravel bikes?
Unsurprisingly, given the chances of crashing (and damaging your bike’s derailleur hanger) are so much higher, UDH has been rapidly adopted by manufacturers of mountain bikes.
Uptake on road and gravel bikes has been notably slower, though.
While that’s set to change with the introduction of SRAM Red XPLR AXS – which uses a direct-mount rear derailleur – I can hear many itching to ask “If UDH is so great, why hasn’t every bike brand adopted it?”
As with anything, though, trying to get bike brands to agree on a universal standard is like trying to herd cats.
Pretty much the only thing bike brands can agree on at this point is pedal threads – every now and again, some genius will even try to reinvent bottle cages.
It’s also true that roadies – for the most part – crash less frequently than mountain bikers, and while replaceable derailleur hangers have their faults, many road bike owners have had bigger issues to worry about until recently (such as press-fit bottom brackets and integrated cable routing).
With the explosion of interest in all-road and gravel bikes, though, that’s all changing.
With a number of major brands committed to making UDH-compatible frames – including Trek, ENVE, Ridley, Cervélo, Scott, Wilier, Specialized, BMC, Bianchi, Lauf, Colnago and many more – we could be on the cusp of a great change.
It’s also fair to say Shimano holds much greater sway over brands than a relatively small company such as SRAM.
You have to wonder whether, had the Japanese brand invented UDH, we’d even be having this conversation.
In its classic style, though, Shimano looks to be in the process of creating its own direct-mount derailleur standard – if its patents are to be believed.
If such a standard ever makes it to market, we can only hope it will be cross-compatible with UDH frames. Otherwise, I might lose all faith in the bike industry forever.
UDH is better, full-stop
In conclusion, while some may decry UDH as 'just another standard', the reality is it's simply better than the compromised replaceable hangers we have now.
SRAM may have thrust its flag in the sand (gravel) when it comes to UDH and XPLR, but with a bit of expansion and a few more options we could have this for the road too – and we’d be all the better for it.
All we need now is a willingness to cooperate from the bike industry.
