This is the main reason why we use paragon round dropouts on our production bikes: hanger support down the line. These dropouts are both easy to design around and easy to fabricate with.
However, just because this is what we do now, does not mean this is what we want in the future. The paragon stuff is great, and the company is amazing to work with, but I think there is room for an engineered hanger that is opensource (well-documented and free to use and modify).
Because the paragon hanger bears the sheer load, it needs a very precise fit:
This makes it difficult to paint. We had to strip and respray several frames that the powder coaters messed up (not the Paragon’s fault, but it’s also not an uncommon mistake).
Their snapring dropout is similar. It requires a precise bore and is not field serviceable (my biggest complaint):
Both these hangers do not work well with plate style and 3D printed dropouts.
Back to UDH:
I really like the standardization that UDH brings. However, the UDH standard is free to use, but not open source. Those two phrases are used interchangeably but fundamentally different. SRAM owns the patent. They can use this to lock out competitors, go after dropout manufacturers, and monopolize drivetrains. I am pretty sure they would not do this, but if the standard were open source, those scenarios could not happen.
Open Source Solution:
This is why I am in favor of creating our own open-source hanger architecture for metal bikes:
- The hanger can be designed to look good and work well with all sorts of dropouts
- 1.125in round, 1.5in round, sliding, 3D printed, plate, etc…
- The hanger dimensions and dropout design will be well documented
- Open source allows people to freely use and remix the design
- Hangers will be standardized and readily available
- Hangers could be produced by anyone
- Paragon/BFS will still be able to make and sell their dropouts and hangers
I think it’s a win-win for everyone involved: dropout manufacturers, framebuilders, hobbiest, and custom metal bikes.