Sram co-axial is coming to gravel. Sram development riders are currently seeking UDH gravel frames.
Yep. I am successfully using UDH with Ultegra and DA Di2. Sure we could have a dedicated hanger for just road but the mtb hanger does work.
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most beautiful UDH dropout I have seen!
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That’s a surprisingly compact UDH dropout!
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Thanks. I’m not happy with where the wire ended up. That kind of irks me to be honest. It should have been on the underside. 
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In talking with my rep, the application for the UDH standard is for the licensing of the UDH branding and not necessarily the use of the UDH standard itself. So you can make a hanger and a dropout that would fit it, but you couldn’t legally put the UDH branding on it or the hanger.
There has been some talk around the existance of some UDH-compatible Shimano DM hangers. But beyond that I’m not sure what the option would be at this time.
The UDH was originally developed to work with Trek Split-Pivot suspension designs. This was the critical limiting case of the UDH design. Also necessary if you want industry-wide adoption unfortunately.
These were the dropouts that I had designed to work with UDH. I’ve tweaked my workflow to work with squared off ends but I know that doesn’t work for everyone. I’ll be working on a second much lighter version later.
Interestingly when you approach it from the standpoint of system weight, they aren’t that far off of the Syntace Dropouts.
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@WHilgenberg Nice work!
With the big guns like Trek and Santa Cruz committed to UDH and probably many others to follow, to me it makes sense to figure out a solution that works with metal bikes.
I’m on board with the idea of an asymmetric design so the NDS dropout isn’t as bulky. But I’d much prefer to work with a round interface. It’s one less angle to worry about.
What would be neat is if Paragon made a DS UDH dropout that you could pair with a NDS snap ring dropout. That way they’d only have to design and produce one extra SKU.
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It could probably be prettier 
but it’s about 46g with a 22mm wide, 25.4mm diameter CS attachment point and a 17mm wide, 19.05mm diameter SS attachment point.
Never designed something for CNC machining. There’s probably a whole host of problems with the design or ways to simplify it to save costs.
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I have many thoughts about UDH but I will only add what my conversations with SRAM engineering have given me regarding road bikes. They said that technically the UDH can accommodate a cassette size down to 36t.(maybe 33t. I can’t remember and it’s in my work email which I won’t see til Monday) After that SRAM says the b tension screw is out of adjustment range.
For myself, I don’t see any reason why SRAM wouldn’t develop a direct mount derailleur for road bikes. It kinda sucks for metal bikes but the Mountain bike derailleur is all over every bike publication with spy shots and patent discussions and it hasn’t even officially launched yet.
At work we just launched a new road bike (Fezzari Veyo) that uses the same interface as UDH but utilises our own derailleur hanger that has the correct dimensions and b tension screw tab angle for road derailleurs. SRAM told us we couldn’t use the UDH logo or name but they allowed this use of the interface.
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That’s very interesting. I just finished a road/gravel UDH dropout design, put a derailleur mockup on it, and thought it really didn’t look quite right. Since making a completely different hanger a) isn’t really feasible at my scale and b) defeats the point of UDH for this application, I guess I’ll be going in a different direction.
Could you just change the stop location and allow the hanger additional clockwise rotation?
That’s possible, but has some drawbacks. By rotating the entire hanger you do change the angle of the derailleur but also its position, which can cause some real shift quality issues. That would also mean that it won’t behave properly when going back to a bigger cassette too.
The other issue for me is more a principle thing - if I’m designing something from scratch, I think it’s a waste of time and resources to intentionally make something out of spec. A better solution would be a different hanger to fit the same dropout, or to simply not use UDH for road applications right now. I’m taking the last option and starting over - I’ll probably make a dropout to fit Paragon snap ring hangers.
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You can do this now if you want, check out DR1103:
However, the asymmetry will give you fits. We’ll sell you either side of any of our dropouts separately.
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Do you have any plans to manufacture this? If not, do you mind if we draw some inspiration from it?
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By all means please. I’d rather buy it from you knowing it’s been vetted by professionals.
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After about 20 design revisions I ended up going with a two piece design for my first build. It has has been holding up really well so far. I incorporated a little hood to address the note on the UDH drawing about chains occasionally jamming in the top. Since these photos were taken I’ve cerakoted the parts black and it looks so much better. Gives the illusion of a slim flat plate design. Hopefully you can look past my atrocious welds.
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@DEVLINCC Off topic, but that’s a beautiful flat mount execution. I personally can’t stand the look of the “battery pack” on a chain stay. Dropouts look really good too.
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Thanks mate. It’s way easier to build too. Still refining a few things with it though. Looking at combining the drop out and first boss into one 3D print.
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Ignoring UDH will be comparable to ignoring disk brakes or suspension for mountain bikes.
I am really curious to see how Shimano handles this, if they do anything at all. They did something similar to the older Saint groups but got rid of it because people were wrecking frames instead of derailleurs or hangers! But UDH is backwards compatible and even if it’s only benefit was a well received standard hanger, it’s still a positive move.
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This seems a bit of an overreach. I don’t see how the UDH is a significant functional improvement like disc brakes or suspension.
It’s never going to be truly universal and be on frames that use adjustable dropouts or Shimano (TBD…). I’m all for simplification but this seems more like the difference in a bottom bracket standard that SRAM wants everyone to adopt so they will have to use their drivetrains.
What am I missing? Please explain how this is a revolutionary advancement.
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