SRAM launches world's first eMTB specific drivetrain and updated Guide brakes - Dirt

Mountain Biking Magazine



SRAM launches world’s first eMTB specific drivetrain and updated Guide brakes

Hot on the heels of SHIMANO LAUNCHING ITS FIRST EBIKE MOTOR, SRAM introduces its emtb specific drivetrain (which we’re pretty sure is a world first) and some updated GUIDE BRAKES.

Previously on an eMTB you would have to use a standard drivetrain and brake set and hope that it could handle extra demands of an electric mountain bike. Thanks to SRAM that will no longer be the case.

SRAM EX1 drivetrain

SRAM has traditionally designed drivetrains around high cadence-low torque usage. The introduction of eMTBs has turned this on its head as riders can now pound up hills putting down a high torque and turning their cadence right down to achieve the same power output.

Because of this, SRAM has put most of its focus into the cassette and chain on the EX1 drivetrain. The cassette is an eight speed with a whopping range of 11 – 48t (436 per cent) which is almost Eagle levels of spread.

The steps between the cogs are about 30 per cent, which is much bigger than any current drivetrain, SRAM claims this makes them more “purpose-driven” as you can be less subtle about things with the saving-grace of a motor to back up your legs.

It’s also worth noting the EX1 shifter only allows one shift at a time so you won’t suddenly find yourself under powered or spinning out thanks to a mis-shift – this will hopefully mean fewer snapped chains as well.

The cassette is complemented by the new EX1 chain that is wider than a standard chain and therefore claimed to be more robust. It also wraps around a bigger proportion of the climbing gears to reduce wear.

Finishing off the drivetrain is a new crank that is compatible with Bosch, Brose and Yamaha motors. There are also Bosch compatible sprockets available with 14, 16 or 18 teeth and 34-tooth chainrings for Brose and Yamaha motors.

Prices and quoted weights

SRAM EX1 E-crank – £45

SRAM EX1 sprocket – £15

SRAM EX1 X-horizon derailleur – £125 (289 grams)

SRAM EX1 X-Actuation trigger shifter – £40 (122 grams)

SRAM EX1 chain – £20

SRAM EX1XG-899 E-block cassette – £345

SRAM Guide RE brakes



SRAM believes that brakes, as well as drivetrains, take an increased pounding from the rigours of ebikes, so it has also revamped its Guide brakes.

The lever assembly is the same as the current Guide brake, however the four-caliper piston is derived from the Avid Code gravity brake. We’ve actually run this combination before on a Specialized Demo and it was enough to convince us to put the brakes in our Dirt 100, so we’re on board!

The organic pads have also been replaced with sintered ones. This should lead to greater durability in wet, British conditions but they do have a reputation for heating up faster so it will be interesting to see if they can offer sustained performance on an eMTB.

The brakes will be available in June costing £112 (roughly the same as the Guide R brake) with a claimed weight of 415 grams (direct mount, 800mm hose, 160mm CL rotor. Shown above in the photo mounted to Truvativ’s new Descendent handlebar.


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