SRAM X0 DH Groupset 1x10 Speed
Brand new for 2012, the latest X0 10 speed drivetrain now comes in a DH specific package for downhillers after the slickest and lightest drivetrain available to humans. Presenting the Worlds first Carbon DH crankset, Truvativ have outdone themselves with the X0 unit that comes in at a paltry 750 grams including the beautiful CNC machined alloy chainring. While it may seem a little odd to outlay the cash to save some grams on a new crankset, downhillers are waking up to the importance of a lightweight race machine and by saving percentages of weight from various areas of your bike, you can save a substantial amount of overall weight that will help you eek out a few more seconds on your race run.

Bringing 10 speed to DH was a simple decision for SRAM, as the benefits of using a tighter ratio cassette means gears are able to be fired off faster, with more accuracy and less interruption to the riders pedal stroke. The stronger PC-1091 chain is also handy in the sports hardest form of riding where a broken chain can mean the difference between a podium spot and a DNF result. The X0 DH rear derailleur may share a similar aesthetic to the regular X0 unit, but a closer look reveals a bulkier construction with a longer P-Knuckle that makes it perfect for the smaller cassette blocks used on DH bikes. Chassis stiffness is particularly important for crisp shifting, and the X0 delivers here with its stout build and Exact Actuation technology allowing the pilot to bang out shifts with alarming speed and precision. The X0 trigger shifter is partly responsible too however, with its adjustable main lever and dual-position clamp allowing the rider to achieve that "just right" position that allows you to maintain a death grip on the grips while controlling the drivetrain. Of course the big news with the X0 DH groupset is the gorgeous Carbon crankset from Truvativ that uses a DH-specific axle for stiffness and strength, as well as shorter crank lengths that are suited to long-travel bikes. If you're keen to drop some weight off your race bike, though you'd also like to improve the shifting at the same time; SRAM X0 DH is the perfect choice with no compromise.

• Technology: X-Glide, Exact Actuation
• SRAM X0 DH Crankset
• SRAM X0 Right Hand Shifter
• Rear X0 DH Derailleur, Short Cage
• SRAM PC-1091 10 speed Chain
• SRAM X0 10 speed Cassette PG-1070
• Optional: GXP Team Bottom Bracket

Choosing your X0 Drivetrain
With a number of different available options to suit different frames and different riding conditions, you will need to select the necessary components for your bike and riding style.

• Crank Length: Coming in both 165mm and 170mm lengths for different length legs, riders under 6 foot will need the standard 165mm option. Riders over 6 foot should choose the longer 170mm length.
• Bottom Bracket: There are several different bottom bracket styles that the Truvativ X0 DH cranks will fit; 68/73mm threaded bottom bracket shells (frames with 135mm or 142mm rear hub spacing), 83mm threaded bottom bracket shells (bikes with 150mm rear hub spacing), PressFit bottom bracket shells with GXP bearings or Shimano bearings and a GXP adapter, and PressFit 30 bottom bracket shells that require the larger diameter 30mm spindle. Unless you have a PressFit 30 specific frame (less common) you just need to choose between the 68/73mm or 83mm option depending on the width of your BB shell.
• Chainring Size: Most riders will go for the middle-of-the-road 36t chainring option, though more powerful riders will want to opt for the bigger 38t. Smaller riders and those that like to spin rather than mash will appreciate the smaller 34t chainring, though if you find you need to lower or up the ratio down the line, the standard 104 BCD means chainring swapping is a simple and relatively cheap process.
• Cassette Ratio: Depending on what low-end gears you require, you can choose between a tight 11-23t cassette, an 11-25t option or the larger 11-28t ratio. The smaller the cassette, the tighter the ratios and the faster the shifting, however this comes at the expense of lower gearing.