Originally Posted by medic75

I don't want to start a new thread on this, so I figured I would continue this one.

Why does the Tiagra level RD RX400 have more capacity (41T) and a better max low gear (36T) capability than the higher level RD RX810? I would love the capability of a 46/30 crankset paired to a 11-36 cassette, but I feel a little weird removing an Ultegra RD 6800 GS & replacing it with a Tiagra level RD. To add insult to injury, I don't believe the newer 11 speed Shimano stuff is compatible with the 10 speed and lower stuff, but I could be wrong. I like that Shimano finally released this stuff, but this seems a little backwards.