SRAM has unveiled its latest e-MTB specific product, the EX1 drivetrain.
The central feature 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 an optimum 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 optimised, 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 brand said. 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.