Spot the difference? (SRAM Vs Shimano Direct Mount)

Have we done this yet?

So, shall we start debating whether they’ll be compatible or whether we’ve swapped the minor inconvenience of having to track down a CNC’d trinket occasionally, in return for having to replace the entire chain stay if we want to swap drive chains?

SRAM:
https://patents.google.com/patent/US20220063763A1/fr

Shimano:
https://patents.google.com/patent/US20220204135A1/en

having to replace the entire chain stay

All eyes on Trek… and anyone else with a pivot around the hub axle… but they’re the big one.

The rational half of me says of course they’ll be the same. The UDH design didn’t limit you or require anything from shimano which supported sram. A frame which can take a UDH but doesn’t include one even takes a few pence from sram’s bottom line so there’s zero reason for shimano not to use the same method of mounting.

The realistic half of me says they’ll use a 13.5mm radius contact patch with a rib at 13.8mm instead of the flat 14mm one for UDH

Shimano would need to get the, free, licence from Sram to use UDH specs – I can imagine that would stick in their craw a bit

Generally we see more stick for SRAM for this, yet IMO a lot of this is caused by Shimano, their patents and behaviour around enforcement.
Some examples are Microspline for Shimano 12 speed cassettes, rather than agreeing to the free XDR standard from SRAM.
The DI2 integration with Hammerhead computers is another crazy step by Shimano, and that is includes them refusing to use the open Ant+ standard, and insisting on continuing with the private version.

This and other issues (like their inability to make a usable crankset power meter) greatly reduces my opinion of Shimano. I see it as wasteful, petty and behind the curve.

rather than agreeing to the free XDR standard from SRAM

Free, but controlled. Why build a multi year plan of design, production and marketing around a licence that must be agreed by, and could be withdrawn by, a competitor? It makes no sense. If XD and XDR were truly licence free for Shimano to use, like HG was for SRAM to use, the outcome might have been different… but Shimano would have been crazy to risk being dependent on an XD licence (or a Transmission direct mount licence in this more recent example). Also, XD means super expensive, or super heavy cassettes… most people don’t want either.

Shimano would need to get the, free, licence from Sram to use UDH specs

around a licence that must be agreed by, and could be withdrawn by, a competitor?

As I understand it they won’t have to. The frame design is licenced but so long as shimano develop something with enough changes that fits the frame design they can avoid the need to licence entirely. They just have to not clone transmission or a UDH. Admittedly this is not even vaguely related to my area of expertise though.

Also, XD means super expensive, or super heavy cassettes… most people don’t want either.

Really? Sunshine £90 & <300g in 11 speed. Similar offerings available for 12s too.

GX eagle sells for about the same price as xt 12 speed and it’s a smidgen lighter. (rrp is 30% higher.)

looks like TRP are scoping out a direct mount mech too https://bikerumor.com/trp-direct-mount-derailleur-patent/

although it looks more like the old saint type ‘end of axle’ design than the wrap around your dropout of sram and shimano.

Looks like they’re gearing up to just make the UDH a universal* blank design to bolt up to directly on the axle.

TBH I doubt the improved stiffness of the SRAM setup will be a game changer except when comparing SRAM Vs SRAM, even some early reviews seem to conclude it only makes it as good as Shimano was anyway.

The interesting bit seems to be whether all three will end up with the same cassette spacing. I’ve got XD and microspline wheels, and I CBA with the potential faff of them not being compatible. So what I really want to see is either a patent for a longer microspline hub to match upto SRAMs lengthened XD cassette, or an overhanging microspline cassette with the bottom few sprockets machined as a block and an internal locking (making it look a bit more XD like). If it came to it I’d take a GX + Shimano compatible system over T-type just for compatibility, I’d not upgrade into a dead end.

*TRP only