When you view anything within the technological realm, it quickly becomes clear that a system is only as good as components that comprise it. And with the new SRAM XX1 group, this ideology becomes transparent, with each piece engineered to perform flawlessly both individually or as a collective. Leaving no room for debate, the X-Horizon Rear Derailleur embodies this design principle. Reinventing clutch technology and parallelogram design, the XX1 X-Horizon Rear Derailleur is creating a new path in mountain bike component technology.XX1's parallelogram design isn't new to derailleur technology, but a horizontal parallelogram design is, and this feature plays a major role in what sets the XX1 X-Horizon Rear Derailleur apart from its competitors. Unlike a typical derailleur, the X-Horizon derailleur knuckle only moves side-to-side -- not up-and-down. This limits the movement to the horizontal axis, making ghost shifting nonexistent. Looking at the derailleur pulley wheels, you'll notice the offset of the upper-pulley. Unusual in design, the upper-pulley provides a constant chain gap through all of the gear ratios.With the combination of the X-sync chainring, pulley wheels, and a Roller Bearing Clutch, a chain guide isn't needed with XX1. Your chain is tensioned with the derailleur and locked in place with the pulleys and chainring. This system prevents chain drop in all-mountain scenarios. Also, combining the Roller Bearing Clutch and parallelogram design means that you'll never get chain slap -- saving your chain stay from looking like the marmots got to it. Taking a step even further, SRAM even made the derailleur to withstand repeated hits while you're navigating through a rock garden in order to eliminate the chance of throwing the chain. SRAM has gone as far to say that you have a better chance of dropping your chain with a front derailleur than you do with an X-Horizon rear derailleur and X-sync chainring.The Cage Lock technology on the X-Horizon derailleur adds convenience to your bike maintenance. While installing a new chain, swapping tires, or changing a flat on the trail, you can lock your derailleur in place for easy adjustments. Just push the cage forward to create some slack, and lock it into place while you work on your bike. No extra tools are required to make this happen, making trail emergencies where you need to remove your wheel a simple fix.The SRAM XX1 X-Horizon Rear Derailleur is available in the color Grey/black and has an approximate weight of 220g. Please note that it's not compatible with a double or triple crank. In fact, it is only compatible with the XX1 shifter and cassette.
Weaknesses: expensive, very sensitive to adjustments
I purchased the whole group, shifter, cassette, chain, derailleur and crankset. I do not understand the need for 11 gears I use 5 of the gears on the cassette. The derailleur took a crap after about 50 miles of riding. The clutch needle bearings gave out and it strained to shift from 2nd to first. I am getting new one from SRAM they need to make the whole package under $900.