Everything you need to know about light E-MTBs

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Everyone is talking about light E-MTBs. These lighter e-mountain bikes open up new possibilities for ambitious mountain bikers. In this article we will explain what this new category is all about and what advantages and disadvantages light E-MTBs have to offer.

History of development

In recent years, most manufacturers in the bike industry have focused on the development of E-MTBs with the highest possible battery capacity and particularly powerful motors. These bikes were mainly used for long bike tours or to give maximum support on technical climbs. Mountain bikers who mainly ride extensive tours with many meters of altitude appreciate these features.

The downside: Large batteries and powerful motors increase the overall weight of the bike. This means that the bike’s agility, when compared to conventional mountain bikes, suffers as a result. And this is exactly where the concept of the light E-MTB comes in. Through the use of smaller batteries and lighter motors, the handling characteristics of modern light E-MTBs are increasingly approaching those of conventional trail- and downhill bikes.

In general, the following applies to the light E-MTB segment: Efficiency, riding dynamics and performance are more important than battery capacity and range. At ROTWILD, all e-mountain bikes from the R.375 series, such as the R.X375 All Mountain Bike, are part of this development. With these models, the focus is not just on lowering the overall weight by using lighter and smaller batteries, a full carbon frame and lighter components like conventional MTB wheels. Importantly, the kinematics of ROTWILD’s light E-MTBs are also more playful and tighter, closer to those of aconventional mountain bike, thus inviting more dynamic riding. This is supported by a geometry that features a relatively steep seat angle and a low standover height. The former makes pedalling easier while the latter allows the use of seatposts with a lot of extension. A low saddle ensures plenty of freedom of movement on the descent. This allows you to use the low weight playfully on the trail, much as you would on a mountain bike without a motor. In combination with the powerful Shimano EP8 motor, these bikes are ideal for thoroughbred mountain bikers.

The new ROTWILD light E-MTB concept therefore clearly stands out from other e-mountainbikes of this genre. The main differences have been aptly described by Mountainbike Magazine in its test:

"The newly-introduced R.E375 by Rotwild, like their also-new R.X375, is difficult to press into a category. With a total weight of only 19.5 kilos it nevertheless offers the new 85 Nm strong Shimano EP8 engine. This sets it far apart from other lightweight E-MTBs in terms of power, which currently tend to offer torques of 60 Nm (Fazua motor) or only 35 Nm on the Specialized Turbo Levo SL."

ROTWILD rider and community member AndyRW is the proud owner of both an R.X750 and an R.X375. He has experienced the differences between an endurance-oriented big mountain bike and an agile, light E-MTB for himself and explained it very precisely in our forum: "The difference between the models is quite big. The 750, with the Brose motor,ploughs the trail flat, the motto being 'just hold on to it’, and that’s good. With the 375 you’re riding the ‘surgeon’s knife':it's playful and light on its feet and always encourages you to pull off on every little hill." ( full thread )

The most important differences between the three ROTWILD light E-MTBs.

ROTWILD offers three different models with a small, 375Wh strong battery for trail, enduro and downhill use. The Shimano EP8 drive serves as a motor in all the bikes, which has been configured with two different light E-MTB riding profiles. The High Power profile for maximum power, and the Minimal Assist profile with throttled power and lower energy consumption.

These are the main differences and areas of use at a glance:

The R.X375

  • A bike for: Experienced mountain bikers who appreciate a bike with a wide range of uses and prefer to ride trail tours with uphill and downhill sections.
  • Range of use: All mountain, trails with technical and fast segments, flow trails
  • Three special characteristics: playful handling, very agile, feels equally comfortable uphill and downhill.
  • Key technical data (size L): suspension travel: 150 mm (fork), 140 mm (shock) / steering angle: 66.5 ° / Reach: 475 mm / Stack: 636 / seat angle: 75.5 ° / wheel diameter: 29 inches / battery capacity: 375 Wh
  • More info on the R.X375

"This is how an E-MTB must be: agile, with full power when needed. Outstanding."
MountainBIKE Test, February 2021 

The R.E375

  • A bike for: Solidly trained enduro bikers with good riding technique who want to ride relaxed uphill and at full throttle downhill.
  • Area of use: demanding trails, step-downs and root fields, jumps and downhills
  • Three special characteristics: Flat steering angle for maximum smoothness, even when it gets rough. Confident handling even at the limit, steep seat angle for relaxed uphills.
  • Technical data (size L): Suspension travel: 170 mm (fork), 160 mm (shock) / Steering angle: 63.5 ° / Reach: 485 mm / Stack: 636 / Seat angle: 77 ° / Wheel diameter: 29 inches / Battery capacity: 375 Wh
  • More info on the R.E375 www.rotwild.de/bikes/bikes/enduro/re375/pro/ 

"In the Enduro segment, the light concept makes sense because bikes in this category are optimized for fast and aggressive downhill. Climbs are more a means to an end." EMTB Test (June 2021)

The R.G375

  • Target group: Gravity bikers with very good riding skills who need a lot of reserves for the really rough trails and jumps and therefore need to rely on smooth running and safety at high speeds.
  • Area of use: downhill and bike park
  • Three special characteristics: exceptional smoothness, enormous suspension travel, first-class downhill performance.
  • More info on the R.G375 www.rotwild.de/bikes/bikes/gravity/rg375/pro/

"The R.G375 is a specialist among specialists. The light approach means it’s perfect for those who value agile handling over range and comfort. The extreme geometry further narrows down the range of use. If you're not looking for high-speed downhills and big jumps, you're in the wrong place. Those who intend to do just that will find this bike spot on." EMTB Test (December 2021)

Range of Light E-MTBs

The different battery capacities of big mountain E-MTBs and light E-MTBs automatically result in different ranges or altitudes that are achievable (for example, how many meters of altitude can a rider manage with one battery charge?). Various parameters such as level of support, gear-shifting behavior, motor type, rider weight, personal fitness, steepnessof terrain and much more influence the energy consumption of the battery. Additionally, body weight is a determining factor: whether it’s a 60kg featherweight or a 90kg heavyweight in the saddle can make an enormous difference. Therefore, it is impossible to quantify the exact range of a light E-MTB based on its battery capacity.

The ROTWILD bikes from their R.375 series were deliberately developed for mountain bikers for whom range is not a deal-breaking issue. A light E-MTB rider is well aware that the bike’s range is not only determined by the battery, but also by their own legs. Anyone who buys an R.375 bike, for example, should have no problem coming home with an empty battery or riding the battery till empty on the last climb. Downhill and home is then done on pure leg power.

Experiences from the ROTWILD Community

In our community there is also a lively exchange of experience about the range of the 375 Wh battery. These practical experiences provide a good overview of what you can expect from a modern, light E-MTB from our Aggressive Series in terms of range. As an example, we’ve re-published two posts from two users, "EsZet" and “zeitvier", below. They added their personal parameters from various tours in a thread on battery consumption. This info provides a useful orientation to answer the question: "How far/how high can I get with a 375 Wh light E-MTB battery?".

EsZet: "I deliberately chose a 375 Wh battery because I simply wanted to have a light e-bike and still be active myself. I usually ride in a mixed bike group (bio/e-bikers), so the Eco mode in profile 2 is sufficient as a support level. However, I also often ride without a motor. How much battery I need depends, of course, on the route profile, but I have a rule of thumb: about 20% battery is used for every 400 meters of altitude. My last tour here in the Odenwald: 77.12 km, 1,428 vertical meters, 16.4 Km/h average speed, consumption approx. 75% battery."

zeitvier: "Another tour with my R.X375: Waldecker Upland, route: 40 km, 95% field and forest paths, 928 vertical meters, average speed 16.5 km/h. Support: Profile 2 (factory), mainly ECO mode, only a few hundred meters with TRAIL mode. Features: quite a few paths blocked by trees fallen in the storm. I could lift the bike over a few, but we also had to turn back a few times. Battery: arrival with 2 bars. Intermediate conclusion: consumption with my riding style and condition around 1- to maximum 1.5% battery charge used per kilometer. With that one can calculate in any case. The buddies riding with me all have larger batteries (up to 650 Wh) and achieve around 1% consumption per km fairly constantly." 

These are just two examples. Many more field reports on the range of different light E-MTB tours can be found in the Tech & Talk forum under the thread "Range R.X375 - Experiences".

Conclusion

Light E-MTBs are aimed specifically at mountain bikers for whom agile, playful bike handling (like they are used to getting from their conventional mountain bike) is very important. Those who ride a light E-MTB want to power out and cover many trail meters in a short time. Light E-MTB users consciously accept a lower battery capacity in favor of a reduced overall weight, and the resulting handling advantages. In addition, light E-MTBs are much better suited for riding in mixed groups (organic and e-bikers), which increases the shared fun.

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