Test / E-MTB: The new Specialized Levo Gen 4 also features the Specialized 3.1 drivetrain, succeeding the well-known Specialized 2.2. Although they once again collaborated with Brose on the motor, Specialized has modified the motor, software, sensors, and the entire ecosystem so extensively that it can rightly be described as a truly unique Specialized system—even more so than its predecessor. To what extent does it fill these big shoes? To answer this question, we visited the lab and the test bench to gather initial practical impressions with the S-Works version.
If you're interested in the drivetrain's performance and capabilities in combination with the new Levo Gen 4, we refer you to our corresponding review. This article focuses exclusively on the drive system itself.
Specialized Levo Gen 4 in the test: With more power and a bigger battery on the throne?
E-MTB / Test: With the fourth-generation Levo, Specialized is launching a thoroughly redesigned version of its successful e-mountain bike. While key specs like 160 mm of front travel, 150 mm of rear travel, and the mullet wheels (29"/27,5") seem familiar, a lot has changed beneath the sleek exterior, especially in the drivetrain and frame details. All models at launch will come […]
Hardware and technical specifications: Everything is new!
The heart of the system is the motor, which was developed from scratch in collaboration with Brose. This also means a farewell to the beloved and simultaneously hated drive belt inside. Instead, a classic transmission with steel gears is used. Plastic has been completely dispensed with in favor of durability. Unlike its predecessor, however, Specialized has not only adapted the software of the new drive, but has also made changes to the hardware. The aforementioned gears feature a so-called DLC coating ("diamond-like coating"). This is intended to ensure consistent operating noise regardless of the motor temperature and also to prevent wear.
The motor has gained weight: It weighs around 3,2 kilograms, about 300 grams more than its predecessor. This is likely the price for the internal changes. If the promises regarding durability prove true, most buyers will be happy to accept this compromise. The Specialized 3.1 drive is offered in two performance levels, with identical hardware and the differences realized via software:
S-Works engine: Up to 111 Nm torque and 720 watts maximum power (manufacturer information).
Standard 3.1 engine: Up to 101 Nm torque and 666 watts maximum power (manufacturer information).
Our review primarily focuses on the more powerful S-Works version, as we've only been able to ride and measure it so far. Will there be a software upgrade from the standard to the S-Works motor in the future? This is currently open, but seems rather unlikely. However, given the relatively modest differences in the nominal specifications (10 Nm, approx. 50 W), we don't expect a fundamentally different riding experience.
A true innovation: The operating voltage is over 50V, and the charging voltage is even higher at 59V. This is significantly higher than most common systems (Bosch/Shimano: 36V; new Brose, Pinion MGU, Sachs RS: 48V). Theoretically, a higher voltage could mean lower currents for the same power output, which could allow for less heat loss and thinner cables – potentially increasing the efficiency of the overall system.
The Specialized 3.1 drivetrain on the test bench
We once again tested the performance at PT Labs. You can find more detailed information in our comprehensive test video on YouTube.
Performance values and cadence behavior
The mechanical engine power was determined by measuring the power at the rear wheel and subtracting the power supplied by the rider (standardized to 250 watts at 75-80 rpm for the maximum power measurement).
Maximum power: Our measurements yielded around 650 watts for the S-Works version. This puts the drive unit in the upper mid-range, clearly above systems like the Shimano EP801 or Bosch Performance Line CX (Gen 5), and also significantly above its direct predecessor. However, it doesn't come close to the brute power of a DJI Avinox. The deviation from the manufacturer's specification of 720 watts could be due to measurement-related reasons or to the fact that Specialized specifies the electrical power, while system-related losses occur at the rear wheel – a well-known phenomenon with all drive units.
Power at 100 W input: Even when pedaling at just 100 watts (simulating normal touring), the motor delivers a decent amount of thrust at the highest setting without requiring excessive pedaling. Interestingly, the predecessor was a bit more generous in its power output.
Power development (progressivity): In Turbo mode, the motor exhibits a distinctly progressive characteristic curve. It requires some input to respond, but then picks up significantly. The maximum power we measured of approximately 650 watts is achieved with approximately 170 watts of rider input (at a cadence of around 77 rpm).
Cadence behavior: We also examined the behavior across a broad cadence range, using a more realistic input power of 130 watts. The characteristics revealed here are surprisingly stable and docile – reminiscent of Bosch and significantly more consistent than its predecessor. The "sweet spot," or optimal range, is almost reached at low cadences around 60 rpm. This means that you don't have to pedal furiously to access a lot of power. Up to around 100 rpm, the power increases slightly, after which it only drops slightly – no drastic drop or excessive increase in power at high cadences like with some other motors. The assistance is maintained up to around 135 rpm before dropping off significantly. This consistent behavior across different cadences makes the motor very intuitive to ride; you quickly get used to the predictable response, especially on technical climbs.
Thermal stability under continuous load (derating)
To test performance under sustained high load, we revised our methodology and optimized it for practical relevance. We used a 15-minute test window with a constant 250 watts of input power as a benchmark—a significant load that rarely occurs without a break in the field. We also observed the entire process for up to 20 minutes ("extended window").
In the 15-minute benchmark, the Specialized 3.1 S-Works motor performs flawlessly. It maintains a very consistent power output and remains at around 95% of its output at the end of the window. This outperforms its already excellent predecessor and is significantly ahead of Bosch drives. Unlike drives with highly fluctuating power output (e.g., the DJI Avinox), the Specialized 3.1 remains very consistent.
After approximately 15,5 to 16 minutes of continuous use under these harsh conditions, a noticeable derating begins, reducing the power to approximately 75% of its maximum. This behavior, however, appears controlled and stable. The motor maintains this reduced level, which suggests a preventative measure rather than critical overheating. Reaching this derating range in practice is likely to occur only under extreme conditions (heat, very long, steep climbs, high rider performance) and is therefore the exception. We do not see any danger of the motor shutting down completely in the case of the Specialized 3.1.
Energy consumption and behavior when battery level is low
We deliberately refrain from providing specific consumption figures (e.g., Wh/km). These depend too heavily on external factors such as tires, riding style, or terrain and offer little real comparison value. Generally speaking, drives that offer more assistance with less effort tend to require more energy. However, the basic efficiency of modern motors is very similar. Specialized emphasizes that this should be significantly improved with the new motor—to verify this, we should wait for the experiences of different riders over the next few months.
Interesting, however, were the observations during a complete discharge cycle of the 840 Wh battery on the test bench. Unlike many systems, where performance drops noticeably as the battery level drops (due to the falling cell voltage), the Specialized 3.1 maintains its performance astonishingly constant. Even with just 1% remaining charge, the power was only about 50 watts lower than with a full battery. This is likely an advantage of the comparatively high system voltage. The downside: There is no "limp mode" or gentle reduction shortly before the end of the charge. If the display jumps to 0%, the motor assistance disappears abruptly. You have to get used to this – there is no buffer for the motor (except for lights, gears, etc.).
Cut-off curve at the speed limit
At the legal assistance limit of 25 km/h, Specialized makes noticeable use of the available power. The motor delivers full power up to and beyond the 25 km/h mark and only then fades out, although the assistance feels noticeable for a comparatively long time. This can be an advantage for riders who often ride at this limit.
Support modes and innovative customization options
In addition to the familiar standard levels Eco, Trail and Turbo, there are new options:
Auto mode: A new, adaptive level that dynamically adjusts assistance based on factors such as incline, cadence, and rider input – similar to the DJI Avinox. Unfortunately, this assistance mode wasn't available on our test bike at the beginning of the year, so we don't yet have any relevant experience with it.
Dynamic Micro Tune: A further development of the well-known MicroTune. Using the handlebar remote, you can adjust the motor's progressivity, not the maximum power, on the fly, in 10 steps. Important: The full motor power can be achieved in each of the 10 steps; the step only determines how much effort is required. The scale ranges from "10/100" (very high effort required, high progressivity) to "100/100" (very little effort required, equivalent to Turbo). Our measurements show, for example, that the "30/100" step (similar to the standard Trail mode) requires around 400 watts of input to release maximum assistance. We really liked this direct adjustment option while riding.
Shuttle Mode: This familiar mode (adjustable to Off, Low, Medium, or High) is designed to facilitate the energy-saving "shuttle up" to the trailhead. Measurements in "High" mode showed, compared to the normal Turbo mode, that the motor releases more power earlier and across the entire cadence range. Furthermore, power remains more stable at high cadences (over 100 rpm) and drops less sharply. This is ideal for riders who want to exert even less effort in Turbo mode, although this naturally increases energy consumption.
The battery system: 840 or 600 Wh and range extender
With the new 3.1 system, Specialized consistently relies on a modular approach that is intended to offer the user flexibility.
Main battery 840 Wh: This powerhouse for maximum range is housed in a solid, IP67-certified aluminum housing. A clear practical advantage is the new, convenient side-loading system from the down tube. However, at approximately 4,4 kg, the battery weighs a considerable amount and is partly responsible for the Levo Gen 4's bulky down tube. In terms of energy density, the battery can't compete with Bosch, DJI, or FIT. So, maximum capacity is traded for greater weight and more space. The 840 Wh battery comes standard on all current Levo Gen 4 models.
Main battery 600 Wh: This lighter alternative (approx. 3,2 kg according to Specialized) uses the same mount as the 840. Thanks to an adapter piece, it can be easily swapped via "plug and play," underscoring the user-friendly modular concept.
The Range Extender: More than just an additional battery
The 280 Wh range extender (1,6 kg according to Specialized) is a core element of the modular design. It is mounted on the down tube and securely mounted via the special "ZeeCage" bottle cage and a third anchor bolt. It connects to the charging port via a custom cable with a secure click mechanism.
The option to ride the bike with just the range extender is particularly practical. While this only provides about half the engine power, it's an interesting way to reduce weight for short rides or when every gram counts.
Intelligent unloading management: automation with pitfalls
The interaction between the main battery and the range extender follows a fixed logic that the user cannot influence. The system attempts to discharge both batteries in parallel. If the charge levels are different, the battery with the higher charge level is discharged first until both are equal. Only then does parallel charging continue. When driving, this can mean that you initially experience noticeably reduced power if the range extender has a higher charge level than the main battery and cannot deliver the full system performance. This is an important point to keep in mind. If in doubt, it is best to start with the range extender directly; then you will avoid such problems.
Chargers: High voltage, short charging time
Two chargers are available for the new Specialized 3.1 drive system. In addition to the standard charger with a charging current of 5 amps, there is also a so-called Smart Charger. This can charge the batteries with up to 12 A charging current in record time. The Smart Charger is included exclusively with the Levo Gen 4 S-Works. It is available as an aftermarket accessory for a hefty €499. A button on the charger itself allows you to set the charging speed: Eco (3 A), Standard (5 A), and Fast (12 A). This also allows you to limit charging to a maximum of 80%.
Since both chargers charge at a high voltage of 59V, the charging power is (maximum) 295W for the standard charger and 708W (!) for the smart charger. The standard charger is therefore far more powerful than the Bosch charger with 4A and even outperforms 6A chargers for 48V systems. The smart charger sets new records and even puts the rightly praised fast charger for the DJI Avinox system in the shade. However, the extremely high performance of the smart charger does have one disadvantage: The massive aluminum charger is significantly larger than conventional chargers and, at around 2,5 kg, is also very heavy. In terms of weight and dimensions, the regular charger is in the range of what you would expect from Bosch, Shimano, and the like.
Charging times (manufacturer information)
| Rechargeable battery | Loading time (0-100%) | Maximum charging current | |
|---|---|---|---|
| Standard Charger | 840 Wh | 03:45 hours | 5A |
| Smart Charger - Standard | 840 Wh | 03:25 hours | 5A |
| Smart Charger - Eco | 840 Wh | 05:45 hours | 3A |
| Smart Charger - Fast | 840 Wh | 02:05 hours | 12A |
Included with our test bike was the Smart Charger, which we also used to perform our own measurements in the fastest mode for the 840 Wh battery:
0-50% in 00:39 minutes
0-80% in 01:05 hours
0-100% in 02:08 hours
This undoubtedly makes it the fastest charger for e-bikes currently available. Charging up to 80% is particularly impressive – after that, the charging current decreases to protect the cells. This is also reflected in our measurements.
Connectivity and app features: The smart brain
The latest Specialized app for iPhone and Android expands functionality and contributes to the overall package. It offers the usual range of features, from motor and display customization to dynamic assistance adjustment via the Smart Control feature to OTA software updates and a system lock as an immobilizer.
You can find out more about the functionality of the Specialized app in the corresponding segment of our test video.
A new feature on the Specialized Levo Gen 4 is the ability to customize all motor support settings directly on the bike. This allows you to leave your smartphone in your pocket, backpack, or even at home.
The Specialized 3.1 drive in practice
In addition to the theoretical measurements on the test bench, we were also able to gather detailed practical impressions of the new drive. For this purpose, we attended a press camp on Madeira at the beginning of the year at the invitation of Specialized.
Noise development: An audible companion
First, the bad news: The Specialized 3.1 motor is louder than its predecessor. Given the move away from the belt drive, this was to be expected, but it may still disappoint some. But there's also some good news: The new motor is far from loud. Depending on the scenario, it's roughly on par with the highly praised noise level of the Bosch CX Gen 5. However, the even more powerful DJI Avinox is even slightly quieter in most situations.
The engine's tonality is also different from its predecessor: The hum has given way to more of an electronic buzz, which is clearly audible, especially at high power and high speeds. However, when the engine isn't pushed to its limits, it's barely noticeable and fades behind the tire noise. As is often the case with noise, if in doubt, always try it before buying.
On the trail, the new Specialized 3.1 motor shines with absolute silence. Even during strong vibrations, there's no rattling to be heard – fantastic!
Basic character: The typical Specialized feeling is retained
The good news for fans of the previous Specialized/Brose drivetrains: The characteristic ride feel – natural, smooth, and harmonious – is retained with the new 3.1 drivetrain. The increase in power and torque is clearly noticeable, but not unpleasantly overpowering. However, this also means that you won't get the unbridled punch that, for example, the DJI Avinox or the Sachs RS offer.
When starting off, even at high support levels, the motor is rather gentle. This is also the only minor criticism in the test: a sometimes noticeable slight delay – a perceived "half a second too long" – before the motor responds when starting off. While this behavior can be influenced by the "Acceleration" setting in the motor settings, the motor quickly becomes very nervous. The new Bosch CX and the DJI Avinox manage the balance between powerful yet well-controlled acceleration right from a standstill somewhat better.
Power delivery: Buttery smooth and extremely controllable
Once you're moving, however, the motor really shines. The power delivery? "Smooth as butter" and extremely controllable. Although the drivetrain can deliver massive power when you demand it, it never feels boisterous or overwhelming. There's no feeling that the motor is going to "run away from you." Rather, it's a helpful, good-natured companion that never takes center stage, even in tricky situations. This excellent controllability makes the drivetrain ideal for technically demanding terrain. It allows you to master even the most difficult passages with great precision and control, allowing you to tackle challenges that might previously have seemed impossible.
Another major factor here is the system's excellent trailing ability: While this is present in almost all current drivetrains, Specialized could do even better. Even in the long setting, it never seems to take control away from the rider, but rather steps in in those situations when pedaling isn't possible. Great!
Dynamic MicroTune in practice: Game changer on the handlebars?
The Dynamic MicroTune function, already described in technical terms, proves to be a real highlight in practice. After a short period of familiarization, it quickly became standard in my test. The ability to continuously adjust the motor's character while riding – depending on the terrain, fatigue, or desired riding feel – allows you to switch instantly from a feeling of high assistance (similar to Turbo) to a mode that requires more effort (similar to Trail) without changing the main mode or stopping. This gives the bike enormous adaptability on the trail.
