Drivetrains are often overshadowed, when upgrading your bike, by other components such as suspension and brake systems. Recently however, I’ve found that the changes I made to my drivetrain have made a drastic improvement, making the shifting fast and accurate as well as being far more silent whilst out riding and racing. When selecting drivetrains the choices in brands can be narrowed down to the two most reliable options, SRAM or Shimano. The changes I made to my bike's drivetrain may be seen as strange and out there but I use the same setup as professional EWS racer, Jared Graves. I upgraded my drivetrain with the addition of a new Shimano 11-speed XT derailleur and shifter, and to a SRAM X1 cassette to optimise efficiency and reliability.
Now this may sound strange, pairing Shimano and SRAM, who does that, right? But I have found it to be extremely effective. My reason for choosing the SRAM cassette over Shimano's alternative comes down to the weight factor. As an Enduro racer, I look to save every fraction of weight, which helps improve how the bike rides and makes it easier to survive a full day out there on the hills. The choice of Shimano for the derailleur and shifter was simple; at the time I was already running Shimano brakes and the I-Spec B technology allowed for a cleaner cockpit by attaching the shifter to the same mount as the brake lever. The other reason for choosing Shimano for the drivetrain is that the derailleur sits closer to the wheel and is less prone to rock strikes with the offer of great durability. 
After installation I have found that the shifting is extremely crisp and reliable, whether it be a quick afternoon spin or a long pedal out in the woods, without the need for any mechanical attention. The reasons for the SRAM cassette being lighter is their Dome technology with a semi-hollowed out internal area, reducing weight and making for a lighter design than its rivals.So if you are in the market to upgrade components on your bike, I would highly recommend this setup - for the reliability and crisp shifting for long rides, over weeks on end, try the pairing of Shimano derailleur/shifter and SRAM cassette. After all, if 2014 Enduro World Series champion Jared Graves runs it then it must be good! Take my word for it.
By Toby Greenwood - Pushys Sponsored Athlete