In the past, replacing the derailleur hanger on your bike was driven by an accident or incident. Until you broke one, you never thought about it. But in 2024, there are now high-end upgrade options for derailleur hangers, designed to replace the hanger on your bike, even when it isn't bent or broken. Some of these upgrades claim improved performance, while others can even extend the functionalilty of your bike. Are they worth considering, and how did we get here?
Old bicycle frames don't have replacement derailleur hangers
Back in the day, just about every bike frame was made from steel. Steel frames don't have replaceable derailleur hangers, and didn't need them - in the event they get bent or damaged, you can just re-align them - literally bending them back into position with a special tool.
Aluminum, in contrast, can't simply be bent back into position when damaged. Similarly, carbon frames also gained in popularity, and this created the need for replaceable derailleur hangers. Replaceable derailleur hangers are designed to fail - taking the hit in a crash, and sparing the more expensive, and more difficult/impossible to repair frame from damage.
Where derailleur hangers come from
10 years ago, 20 years ago, you likely got the replacement hanger directly from your bike manufacturer, or from a bike shop who carried that brand. There are hundreds of variations of sizes and shapes, with different styles used even within the same brand.
Due to the huge variety, they could be hard to find and were often a special order item. Worse, they could disappear from the market entirely as styles aged, making replacement on older frames impossible, leaving owners high and dry. They also weren't very high-tech, typically being made of cast aluminum, but they did the job.
HIgher quality aluminum options arrive
To address this need, brands like Wheels Manufacturing began offering higher quality replacements aftermarket. Instead of buying a hanger from Specialized or Trek, you could now buy one from Wheels Manufacturing or one of their competitors. They provide visual tools, allowing non-technical people to visually match the hanger to your frame and get the right model, and had a huge selection, even styles to fit bikes that hadn't been on the market for a while.
These are typically machined from 6061-T6 aluminum with tight tolerances and work great, and since Wheels Manufacturing makes them for a huge variety of makes/models... the availability problem is solved. Even today, if you have a bike with a replaceable hanger I'd recommend Wheels Manufacturing when you need a hanger.*
3D printed titanium derailleur hangers?
Several other companies have attempted to enhance and improve the basic humble aluminum hanger.
Notably, Silca has introduced a 3d-printed titanium hanger for a few makes and models. There are some other brands as well. Originally designed for World Tour teams, these promised increased stiffness - which makes sense, since it could lead to improved shifting performance, and some weight savings (that said, even basic aluminum hangers are very light.)
Similarly, Framesandgear from Denmark will sell you an aftermarket hanger in pink, gold, or oil slick - colors that major players like Cannondale or Giant would never dream of offering. 3rd-party brands fill a void in the market.
How does this relate to SRAM's "T-Type" Transmission and UDH?
The bicycle market moves quickly, and in some cases, 3rd parties have stepped in to provide updates that bike brands don't or can't offer. SRAM's Transmission system is designed for UDH (universal derailleur hanger) bike models, which is relatively new to the market, and found mostly on mountain bikes at this time.
If you wanted to use the T-Type Transmission components on your cyclocross or gravel bike which came with a non-UDH hanger, it was impossible. 5DEV then produced a proof of concept kit for Specialized Crux 'cross / gravel bikes that aren't UDH compatible, allowing them to use SRAM's Transmission. Note that these aren't universal - it only works on select Specialized models - but still illustrates what a more adventurous 3rd party can do.
Homebrew derailleur hangers
Replacement derailleur hangers aren't limited to bigger brands. With the rise of more economical CNC machines and 3d printing options, smaller players and even individual home users are getting in on the act.
For example, I own a Time ADHX allroad bike, and Time offers a typical aluminum hanger on this model. It's what I would call the "classic" style hanger, not using Shimano's "direct mount" fitting, nor the SRAM UDH fitting. Time themselves don't offer either of those.
An enterprising member of the Time Bicycle Fan Page group on Facebook is now offering hangers made to suit select Time models, in a direct mount style hanger. For users running Shimano drivetrains, with direct mount rear derailleurs, users can remove the B link from their Shimano rear derailleur, and instead mount the rear deraiileur to the updated direct mount hanger (you can think of the B-link as sort of a "direct mount rear derailleur to non-direct mount hanger adapter.") This, in turn, could lead to better shifting and easier rear wheel removal.
Always keep a spare derailleur hanger in your toolbox
* Cyclocross racers should order and have on hand a replacement derailleur hanger for your bike, and keep it in your race toolbox so it goes with you to every event. This isn't an item you're going to pop into a bike shop on a Saturday afternoon and find in stock. Without the hanger, your bike is unrideable, and they are easily damaged in muddy cyclocross events. Don't wait until you damage yours to track one down.