Looks like it positions the usual two pulley wheels closer to where chain slap happens, while adding a pulley wheel that remains close to the cassette. In the

Looks like it positions the usual two pulley wheels closer to where chain slap happens, while adding a pulley wheel that remains close to the cassette. In the usual case, you have pulley wheels both shifting and tensioning the chain. Fine for most road bike use cases, but that leaves lots of room for chain slap in gravel and mtb use cases. The viability of this design depends, it seems, on whether it adds less drivetrain loss than a clutch, and if added weight can be kept low.