I think this is the first sighting of UDH on a road bike: Spotted: Ridley's new Noah Fast maximises everything - Escape Collective
Corrections: The Ridley falcn Ronan reviewed last year had udh, and he shared that udh is wider so 1) drag and 2) rub (heel rub).
Obviously, UDH is on Gravel bikes now, and manufacturers are making sure their UDH bikes will also work with the yet released Shimano UDH equivalent (Shimano has provided their UDH specs to manufacturers to work with).
Personally, I’ll be on Red XPLR 13s 10-46 cassette with a 1x 54t front chainring for 2025 road and gravel. But because UDH is currently unavailable on TT/Tri frames, I’m planning on XPLR XG-1271 12s 10-44 cassette with a 1x 58t front chainring. If UDH suddenly appears on something like the Factor Hanzo for 2025 (not holding my breath), I’ll be on 13s XPLR for the 2025 tri season, with a hope that a 13s 10-36 were to also be offered, but 13s 10-46t being awesome for training and most races, for me personally.
The primary issues is the chain staying on the front chainring when the rear cassette cog goes over 30t. When the narrow/wide front chainring is made of metal, such as Absolute Black, I’ve had no issue with a 36t rear cog. But with the all carbon Digirit front chainring, I saw in Kona on a pro’s bike that the chain was pulled off of the front ring when the rear cog was over 28t.
I’m curious to see if Gemini’s new carbon front chainring where the metal insert ensures the chain only touches metal could be a light weight and more secure alternative to Digirit. Gemini’s ring is currently offered up to 46t, but they have stated they are working on 52t. Don’t know if they’ll get to 62 and 64t rings for the likes of Foley, Magnus, KB and Laidlow, and Grand Tour riders.