SRAM EX1 e-bike component group first look

Is an e-bike mountain bike group really warranted?

Components E-bike
The cassette is milled from a solid steel block and forged into shape.

The cassette is milled from a solid steel block and forged into shape (click to enlarge).

Why an e-bike-specific group?

We’ll just get to the heart of the matter and ask/answer that question. No, it is not required, as e-bikes can manage out there with any old drivetrain, brakes, and suspension. But spend some significant time on an e-bike and one will realize that there are quite a few compromises with current systems. The experience can get a whole lot better and SRAM is well ahead of the curve in addressing the issues.

Those issues can be boiled down to the following:

  • Shifting under power is rough and clunky
  • The shift steps don’t make enough of a difference
  • The durability of the drivetrain
  • Brakes don’t have enough power to stop bike precisely

These are all due to two things: The e-assist can double the power of the rider and riders are trained to ‘soft-pedal’ while shifting but the assist motor can be kicking in while the rider is shifting. Also, e-bikes are heavier by about 20-25 pounds of un-sprung weight and it can affect the ride, as the brakes are stressed and the bike pushes into corners or fades in long descents.

The forged block is then milled and treated.

The forged block is then milled and treated (click to enlarge).

The heart of the system

The heart and soul of the SRAM 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 11-48, 8-speed design allows a 436-percent gear range. Based on its testing, SRAM believes this is the ideal e-mountain bike 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 tooth jumps are in 30% increments instead of the usual 16% on normal bikes.

The tooth jumps are in 30% increments instead of the usual 16% on normal bikes (click to enlarge).

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.

The EX1 is seen here on the Moustache e-mtb.

The EX1 is seen here on the Moustache e-MTB (click to enlarge).

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.

The brakes are the most burly available in the SRAM arsenal.

The brakes are the most burly available in the SRAM arsenal (click to enlarge).

Brakes

Guide RE combines SRAM’s Guide R lever assembly with a powerful 4-piston caliper derived from the gravity-focused Code brakes. Highlights include:

  • Guide R lever assembly with Guide technologies
  • 4 piston caliper derived from the Code gravity specific brakes
  • Sintered pads for better pad life in intensive use
  • Weight: 415g (based on direct mount, 800 hose, 160mm CL Rotor)
The EX1 is shown here with a Bosch drivetrain and small front ring.

The EX1 is shown here with a Bosch drivetrain and small front ring (click to enlarge).

The rest of the goods
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.

EX1 X-Horizon Features:

  • 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

EX1 X-Horizon Specifications:

  • Speeds: 8
  • Cable pull ratio: 1:1
  • Max tooth: 48
  • Color: black
  • Pulley bearings material: Steel
  • Cage material: Aluminum
  • Weight: 289g
EX1 X-Actuation Trigger Shifter

Eight speeds are key for optimizing for the e-assist with 30% gearing changes on each shift, alleviating double shifting and over shifting. Single precise gear changes increase battery life and help to decrease component wear.

EX1 X-Actuation Specifications:

  • Speeds: 8
  • Max upshifts/downshifts: 1
  • Multi-position: Yes
  • Part weight: 122g
Going up the 25% grades on the Lake Garda, Italy roads.

Going up the 25% grades on the Lake Garda, Italy roads (click to enlarge).

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.

EX1 Chain Features and Benefits:

  • EX1 chain is wider and designed for the high-torque, heavy-duty use of E-MTB
  • Compatibility: 8-speed
Pricing
  • E-Block cassette: $390
  • Rear derailleur: $142
  • Shifter: $48
  • Chain: $25
  • Brakes: $133 each
  • Crank: $50
  • Sprocket: $20
Summary

We’ve been riding e-bikes on the roads and OHV trails for a couple years now and we have noticed several weaknesses of commuter systems adapted for dirt trails. Most notably, the systems simply cannot handle the dirt, torque, shifting requirements needed for steep, dirt trails. SRAM is ahead of the issue here and is solving several problems that we have noticed. The shifting performance of the EX1 is simply incredible as the rider can shift under power at 20%+ grades. Precise, consistent braking is now available in spades too. Next stop, optimized suspension.

For more information visit www.sram.com.

Photo Thumbnails (click to enlarge)
About the author: Francis Cebedo

The founder of mtbr and roadbikereview, Francis Cebedo believes that every cyclist has a lot to teach and a lot to learn. "Our websites are communal hubs for sharing cycling experiences, trading adventure stories, and passing along product information and opinions." Francis' favorite bike is the last bike he rode, whether it's a dirt jumper, singlespeed, trail bike, lugged commuter or ultralight carbon road steed. Indeed, Francis loves cycling in all its forms and is happiest when infecting others with that same passion. Francis also believes that IPA will save America.


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  • Gerald Capodieci says:

    I really like the large range and agree with less cogs/stronger chain allowed by the 8 speed. I find that I frequently shift 2 cogs at a time just to make a noticeable difference.Today I’m not interested in ebikes but perhaps some day. But, if I could get the wide-range 8 48×11 speed system for my Shimano 1 by bike, I’d do it today.

    • Francis Cebedo says:

      >>Gerald

      Yup, really want to this on a normal bike. Stay on each gear a little longer and avoid the constant double-shift. Advantage is less shifting, much stronger drivetrain and straighter chainline.

  • ian says:

    I’d love a lighter 8 speed wide range cassette for my non-E-bike.

  • Joe Dirt says:

    We’re still pretending e-bikes are real bicycles?

  • GuyOnMTB says:

    E-bikes are not Bi-cycles, in US law they are classified as “motorized vehicles”. They should have their own website. “E-bike” is just a marketing word that is actually confusing to people that may not understand our laws.

  • eric says:

    My response isn’t about fearing change. Motorcycling is a different sport which has been around much longer than mtbing. Stop pretending that these things are anything else. Motorbikes also happen to be awesome too, just different. They also tend to make very poor trailmates with bikes and hikers (oh yeah, and horses…)

    I’m afraid the only distinction between ebike and motorbike is that ebike riders can more easily poach trails. I fear this will end badly with mtb access getting hurt by it.

    Can someone explain again why these are being covered here?

  • DE says:

    Great to see you guys reporting on ebikes now. I rode traditional mountain bikes my whole life like most people, but after getting an ebike, my old Carbon XC bike just never gets used anymore, for the simple reason that I have just as good a work out on the ebike since I cover so much more ground in the same time and have way more fun doing it!

    I travel 2 or 3 times faster uphill and go back down on a long travel bike which is much more fun and safer than the shorter travel XC bike which I previously needed for climbing the big mountains where I live. I can ride up the mountain and down 3x in the same time as I used to do it once on the old bike! Since the pedal assistance cuts out anyway at 25 km/h Going down is the same speed as on a long travel non ebike but going up is just so much faster and more fun now.

  • dirt person says:

    lol these clowns who hate on ebiikes saying they will close trails, have no fookin ikdea that these places were opened by dirtbikes, which have…….motors………wake up you werent the first to ride off road

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