SRAM EX1 is poised to have the same impact on the E-MTB world. EX1 is the first and only drivetrain available today that was designed from the ground up specifically for E-MTBs.

Until the development of EX1, the E-MTB was seen simply as a mountain bike plus electric assistance. Though that definition is not strictly incorrect, the whole, in this case, is significantly greater than the sum of its parts. The experience an E-MTB provides its rider and the demands placed on each element of the entire system are incredibly different than with a traditional, non-electric-assisted mountain bike. Therefore, the thinking simply has to be different.

Building upon information from motor manufacturers, and its own interpretation of problems associated with using a conventional mountain bike drivetrain on an E-MTB, SRAM’s EX1 development team used advanced data acquisition methods for field testing, combined with traditional lab testing, to create a perfect E-MTB drivetrain solution.

The heart and soul of the EX1 system is its E-BLOCK cassette, which is designed to provide the optimum E-MTB gear range, as well as increased battery longevity and component wear life. Its 11- to 48-tooth, 8-speed design allows a 436-percent gear range. Based on its testing, SRAM believes this is the ideal E-MTB gear range.

The 8-speed design incorporates big (30-percent average) steps between gears. The big steps, in combination with the EX1 group’s single-action shift lever, reduces riders’ tendency to double shift. The single-shift design significantly helps chain and cassette wear.

The cassette, machined from case-hardened tool steel, is narrower than a 10- or 11-speed cassette, which helps maintain a straighter chain line throughout the gear range. Engineers were then able to pair the cassette with a slightly wider, tougher chain to increase durability—which is critical in the E-MTB environment, where shifting is typically done at very high torque and low pedaling cadence, versus the low-torque, high-cadence environment of traditional mountain biking.

The E-BLOCK cassette uses a non-XD driver body. The larger virtual front sprocket provided by a midship motor all but eliminates the need for a 10-tooth cassette cog, so the E-BLOCK design’s focus is the larger, “climbing” cogs. By combining the proper climbing gears with motor output, battery power is optimized, and lasts longer given the same conditions.


Shifting performance and feel is signature SRAM. As stated previously, the trigger shifter has been designed to shift once at a time—not multiples—but the action is positive and exact. The EX1 derailleur employs the rugged, X-HORIZON design seen in XX1 and X01 derailleurs, with a redesigned clutch, cage and pulley design specifically for the 48-tooth cog.

Purpose-built solutions mean greater opportunities.

Bold new world

Ever since the first beat-up old newsboy bikes were modified to ride in the dirt, mountain biking has been about defying convention and finding new ways to make the ride better. And each new style of riding requires a perfect solution. EX1 is the world’s first drivetrain system specifically developed for the unique demands of the E-MTB. With proven SRAM 1x technology as its DNA, this group’s heart is the EX1 cassette, which allows optimal steps between cogs for more purpose-driven shifts and providing the best gear range for midship-motor E-MTBs. Each EX1 component is engineered to perfectly complement the system, and the result is quiet operation, intuitive shifting, increased battery life and greater durability. EX1 opens the door to a brave new world of mountain biking.

EX1 E-Crank

Lightweight, durable, stiff and designed specifically to work with Bosch and Brose mid-ship motors, EX1 crankarms are purpose built for the high-torque E-MTB environment.


Features and Benefits

  • Proven SRAM technologies adapted for the demands of midship-motor E-MTBs
  • Compatible with Bosch, Brose and Yamaha bottom bracket interfaces


  • BB compatibility - ISIS
  • Crank arm length - 170mm, 175mm
  • Colour - black
  • Crank arm material – aluminium



SRAM X-Sync Sprockets

Built with the needs of E-MTB riders in mind, and incorporating the same X-SYNC chain management technology found in every SRAM 1x drivetrain, EX1 offers 14-, 16- and 18-tooth sprockets for Bosch motors.




  • Bolt circle diameter - Direct mount
  • Teeth - 14, 16, 18
  • Colour - Black
  • Material - Steel

XG-899 E-Block Cassette

E-BLOCK shifting technology is a fundamental redevelopment of external drivetrain shifting. On the E-BLOCK cassette, the chain has a defined link position on each cog. Cog architecture has been engineered to work with both inner and outer links of the chain, which allows extremely refined shifting for both inboard and outboard shifts. The result is precise and robust shifting performance in any situation, even with full motor support.


Features and benefits:

  • 11-48t, 8-speed cassette machined from case-hardened tool steel
  • Ideal mid-ship motor gear range
  • Increased chain wrap on climbing cogs
  • Symmetric shifting geometry allows fast, precise gear shifts
  • Optimal inboard and outboard shifting performance
  • The big steps between cassette cogs is a completely new cassette technology engineered specifically for the demands of E-MTB
  • Non XD driver body compatible


  • Speed - 8
  • Gearing - 11-48t
  • Cog finish - black
  • Technology - XG
  • Cog sizes - 11t, 13t, 15t, 18t, 24t, 32t, 40t, 48t
  • Cogs on cluster - 5

EX1 X-Horizon Rear derailleur

The EX1 derailleur capitalizes on the robust build and precise shifting attributes of the X-HORIZON design, to create the world’s first derailleur specifically made for E-MTBs. Engineered to handle high-torque, low-cadence shifting across the 11-48 tooth E-BLOCK cassette, the EX1 derailleur gives E-MTB riders clean, confident shifts, so they can spend more time enjoying the ride.

Features and benefits

  • Proven SRAM X-HORIZON design that reduces shift force, ghost shifting and chain slap
  • 12-tooth X-SYNC pulley wheels
  • The EX1 derailleur is purpose built for E-MTB


  • Speeds - 8
  • Cable pull ratio - 1:1
  • Max tooth - 48
  • Colour - black
  • Pulley bearings material - steel
  • Cage material - aluminium
  • Weight - 289g



EX1 X-Actuation Trigger Shifter

It has the proven SRAM shifter technology and authoritative lever feel, but the EX1 shifter has been engineered to deliver one perfectly accurate shift at a time, alleviating double shifting and over shifting. Single precise gear changes increase battery life and help to decrease component wear.

Features and benefits

  • X-Actuation for precise and dependable performance
  • Single shifts reduce over shifting and increase battery performance


  • Speeds - 8
  • Compatibility - 8-speed rear derailleur
  • Cable pull ratio - X-ACTUATION
  • Colour - black
  • Cable length - 2200mm
  • Shifter type - trigger
  • Matchmaker compatible - yes
  • Max upshifts/downshifts - 1
  • Multi-position - yes
  • Part weight - 122g

EX1 Chain

The high torque loads of E-MTBs require tough components. The straighter chain line EX1 offers allows the use of a chain that is wider and more robust than those found on drivetrains not specifically engineered for E-MTBs. The 8-speed EX1 chain has been engineered to run quiet across the gear range and transmit more power to the rear wheel.



  • Compatibility – 8-speed
  • Colour - Grey
  • Chain connector - PowerLock
  • Inner link finish - Polished
  • Outer link finish - Nickel
  • Pin variant - Solid Pin
  • Pin treatment - Chrome Hardened

Guide RE

Guide RE is SRAM's optimized braking solution for today's exciting category of E-MTBs, capable of handling the higher average speeds, more intense use and increased mass due to the presence of the motor and battery. It combines SRAM's proven Guide R lever assembly with a powerful 4-piston caliper derived from the gravity-focused Code brakes. Guide RE provides real, usable on-trail control—optimal power and modulation mean speed can be controlled in all terrain and in all situations, both uphill and downhill.



Features and Benefits

  • Guide R lever assembly with proven Guide technologies
  • Powerful 4 piston caliper derived from the Code gravity specific brakes
  • Sintered pads for better pad life in intensive use
  • MatchMaker X compatible
  • Ambidextrous lever mount
  • Tool-free reach adjust




Weight: 415g (based on direct mount, 800 hose, 160mm CL Rotor)
Blade material: aluminium – stamped
Lever body material: Forged aluminium
Caliper construction: 2-piece
Caliper material: Forged aluminium
Finish: Gloss black
Pad type: Steel-backed metal sintered
Hydraulic fluid: DOT 5.1
Reach adjust: Tool-free
Hose routing angle: Adjustable banjo
Brake type: Hydraulic
Lever pivot: Bushing
Caliper hardware: Steel
Pistons: 4
Piston material: Phenolic plastic