Rear derailleur, still only going to 10
The real question is, how many more times can I get away with that Spinal Tap reference? Until we get to 12 speed, I think.
The rear derailleur has been completely redesigned as well: lighter, with improved clearance for 28-tooth cassettes, a better barrel adjuster, super quiet aeroglide
pulleys, and a better cable path.
The b-knuckle (the top bit of the parallelogram) has been elongated, resulting in better shifting with big cogs. The barrel adjuster, that seemingly innocuous item, gets a sleek wing shape to make it easier to turn with slimy or cold fingers.
The pulleys are still using ceramics, and now include a new tooth profile and material for quieter running and less power loss. A titanium cable clamp bolt is a nice touch, as is the fact that one no longer has to move the derailleur body down manually in order to access to the mounting bolt.
Available for the first time this May will be a WiFLi version of the Red derailleur, meaning you can run an 11-32 cassette and 53/39 cassette without issue. The WiFLi version gets all the same updates as the regular derailleur