Some might recall the ACROS Hydraulic shift system from 5 years ago aimed at the mountain bike market that never quite caught on despite its light weight and features. The Rotor Uno system has some similarities, but is introduced as a whole group for drop-bar bikes.
The biggest question of course is why hydraulic? Antoine Berte, OEM Global Director for Rotor Components explains that hydraulic offers improvement in shift precision, reliability and low weight. The whole system is 400 grams lighter than the Dura Ace 9000 mechanical system. Without a battery, there is arguably a reliability advantage, and with indexing at the derailleur, the hydraulic system, with minimal friction or slop, can deliver a very precise shift.
Another advantage is the lever body has only the fluid reservoir and master cylinder, no complicated shift mechanism. So the body is smaller and lighter than mechanical counterparts. While this rivals electronic systems with similar features, battery life and wire problems can possibly hinder reliability in those systems. Once the Uno system is set up, admittedly perhaps a bit more complicated, system maintenance is said by Rotor to be minimal to non-existent.
The Uno shifter uses a single lever for shifts much like SRAM DoubleTap, though Berte points out that unlike DoubleTap, if you pass the first shift point, and fail to reach the second, ROTOR Uno will not shift at all, whereas DoubleTap will give you that unwanted up shift. The Uno shift lever can be set to shift up one or up to four gears in a single a throw, and if for some unfortunate reason you slice the 3mm hydraulic shift line, you can manually push or pull the derailleur into gear as the indexing is within the derailleur itself.
Another interesting feature is the disengagement lever on the rear derailleur, making for easier wheel changes. A second lever puts the mechanism into the small cog for easier wheel installation.
The Rotor Uno components are entirely manufactured and assembled at the Rotor Component factory in Spain. Partnered with Magura hydraulic brakes, in either disc or rim configuration, the Uno grouppo, without a crankset, will retail for $2500 USD.
More info: rotorbikeusa.com