From Extreme Freeriding to the rigors of World Cup XC, the X.0 system performs with distinction. The superior 1:1 actuation ratio paired with a NEW super-tough carbon and aluminum cage design results in durability and performance.  1:1 Actuation ratio gives lighter shifting effort and is less susceptable to a drop in performance due to dirty cables - go longer without having to replace your cables.  Di.R.T: Direct Route Technology™ means less cable friction for crisper shifts. 
The X0 is best used in conjunction with other SRAM products like the X.9 or X0 shifters, Powerglide cassettes and SRAM Powerlink chains to create a race-ready 9-speed package.

Please note: The following advice is a reccomendation only, your rear suspension design must be taken into account if chain growth occurs when your suspension is compressed.  If in doubt consult your frame manufacturer or base your decision on the cage length of your current derailleur.

To work out if you need Medium or Long cage:

1. Subtract the number of teeth on your smallest front chainring from the number of teeth on your largest front chainring.
2. Now subtract your smallest rear cog from your largest rear cog in the same way.
3. Now add the two subtotals together.

If your total is less than 37T you should select the Medium Cage
If your total is between 38T - 45T, you should select Long Cage

For example:
A 22/42/44T crankset has a front difference of 22T
Paired with a rear cassette of 11-32T with a rear difference of 21T
Adding the two subtotals together gives a total of 43, therefore a Long Cage derailleur would be reccomended.

Cage length (From centre of lower pulley to centre of upper pulley):

• Medium 75mm
• Long 93mm

Features:

• Stylish and Strong! A forged 6061 aluminum B-Knuckle improves stiffness.
• New CNC’d 100% Carbon Outer Cage
• New 6061 Forged Aluminum Inner Cage
• Titanium Main Spring
• Di.R.T: Direct Route Technology™
• 1:1 Actuation Ratio™ Superior Shift Quality
• Outside Facing Limit Screws - Intuitive Adjustment
• Sealed Bearing  Pulleys

Specifications:

• Compatible with all ESP Grip Shift shifters & 1:1 ratio trigger shifters - Not compatible with Shimano Shifters
• 11-34T capacity
• 11 tooth pulleys
• Compatible with 8/9 speed
• Weight:  Medium 197g / Long 203g