Sram rival 1 11sp rear derailleurthe sram rival 1 rear mech delivers incredibly smooth, quiet and reliable shifting even in the most demanding conditions'. '.strtoupper('i')t takes the proven technologies of sram's 1x mountain bike derailleur design and applies them to provide exceptional off road performance for cyclocross use.quiet and smooth shifting performancethe internal clutch design eliminates chain slack, making it almost impossible for the chain to fall of the chainring whilst cycling a real benefit when riding on rough terrain'. '.strtoupper('i')t also creates a noticeably smoother, quieter and higher performing drivetrain configuration for your bike.features cage material aluminium pulley bearings steel sealed cartridge bearings pulley wheel size 12t speed 11 speed cable pull ratio exact actuation maximum sprocket size medium cage 36t long cage 42t weight medium cage 432g long cage 438gtechnologies cage lock wheel removal and installation, as well as chain installation, becomes faster and simpler'. '.strtoupper('j')ust push the cage forward to create slack and lock it into place'. '.strtoupper('x') sync the x sync pulley features a 12 tooth design that helps control the chains lateral movement roller bearing clutch  maximum drivetrain stability even through the most punishing terrain'. '.strtoupper('w')ith roller bearing clutch technology, derailleur bounce and chain slap are eliminated without sacrificing precision'. '.strtoupper('e')xact actuation simplified and stabilised shifting over tight cog spacing found on modern cassettes'. '.strtoupper('b')y using exact cable tension, the end result is the easiest index shifting system to set up and it stays that way'. '.strtoupper('x') horizon the lsquostraight parallelogram design limits all movement to the horizontal axis, which makes ghost shifting impossible while also reducing shift force'. '.strtoupper('f')or quicker, more exact shifting, the large upper pulley offset design maintains a constant chain gap across all gears.buy sram components from chain reaction cycles, the world's largest online bike store.