SRAM

Rival 1 Type 3.0 Rear Derailleur

This is a gravel bike oriented derailleur, but I used it to convert an old 2x10 mountain bike to 1x with excellent results. Note this conversion also involved replacing the crankset with a 1x specific crankset; I wouldn't recommend cutting corners there. The chain stays quiet and in place on rough MTB descents, so this derailleur should do well in any kind of gravel riding situation. The shifting is generally very good -- you push the button and the chain shifts ... 99% of the time. If the drivetrain is filthy and you're hammering the pedals a shift may occasionally be slow, but that's rare enough not to be an annoyance. The compatibility situation is that this uses "Exact Actuation", the system used on SRAM's road shifters and *also* on their older 10 speed mountain shifters. SRAM's newer 11 and 12 speed *mountain* shifters use "X-Actuation", which is different and incompatible. If you've converting from an old SRAM 2x10 system re-using your old "Exact Actuation" shifter saves you a few bucks.