Shimano has filed a patent for a Direct-Mount Rear Derailleur with a rigid "bracket device" that occupies space on both faces of the drive-side dropout, similar to SRAM's T-Type Direct-Mount Derailleur. The patent shows a mechanical rear derailleur with a pulley wheel for guiding the cable to its clamp and the ability to accommodate different size cassettes. Shimano's design reduces the amount of the rear derailleur projecting from the bicycle's axial center plane and increases its rigidity, improving usability. It is unclear whether the design is compatible with SRAM's UDH style dropout or impinges upon SRAM's Transmission patents. Shimano may also be working on an electronic version.
Shimano has been granted a patent for a wireless electronic derailleur that will use a direct mount. The patent describes a derailleur that can use some form of direct mount, and is wireless and electronic. The drawings depict one version where the derailleur is mounted close to the chainstay, and the other where it uses a link that's similar to what Shimano used when they last tried to get a direct mount system off the ground back in 2012.
Shimano has filed a patent application for an integrated rear derailleur that fits directly onto the rear dropout, removing the need for a derailleur hanger and held in place by the thru-axle. The design is similar to SRAM's T-Type Eagle Transmission, which combines a direct-mount rear derailleur with the Universal Derailleur Hanger standard. Shimano's patent includes an "angular position structure" for initial setup and suggests compatibility with different cassette sizes. This patent application suggests Shimano may add a true direct-mount option to its mountain bike range.
