This article is part of our big 2026 motor group test. Click here to read about all 11 systems we tested, discover the latest trends and dive into detailed results from both the lab and real-world testing.
The Bosch Performance update released in July 2025 didn’t just boost the CX motor to 750 watts and 100 Nm – it also reignited the debate over potential power limits for e-bike motors. Now, with the latest Flow app update to version 1.30, the SX motor has received a power boost of its own. The smaller sibling now delivers 60 instead of 55 Nm of torque and, like its full-power counterpart, offers up to 400% pedal assistance. The already impressive peak power of 600 watts – which is unusually high for the light eMTB segment – remains unchanged. What also stays the same is Bosch’s promise for the SX: “Sporting lightness” is what it aims to deliver. We put that claim to the test and find out how the updated motor stacks up against the competition.
The Bosch Performance Line SX in detail – endless possibilities
The Bosch SX drive unit tips the scales at just 2.06 kg, which makes it a whopping 750 g lighter than the fifth-generation CX motor. According to Bosch, this weight saving opens the door not only for light eMTBs, but also for eGravel and eUrban bikes. Like its bigger sibling, the SX is part of the Bosch Smart System, which means it’s fully compatible with all Smart System components. Manufacturers can mix and match from a wide range of batteries, remotes and displays to create their ideal setup. No other brand currently offers this level of modular flexibility. Fancy pairing the lightweight SX motor with the big 800 Wh battery? That’s totally possible. That said, most bikes specced with the SX motor – including the Pivot Shuttle SL/AM we used for this test – rely on the CompactTube 400 battery to keep the overall system weight as low as possible. In the case of the Pivot, the total weight dips below the magic 20 kg barrier. Needless to say, the PowerMore 250 range extender can also be used with the SX motor system, allowing you to increase range on the fly for longer adventures.
When it comes to connectivity, SX users benefit from the well-established and feature-rich Bosch Smart System. The Bosch Flow app, which was continuously refined over the years, enables detailed customisation of the support modes, and includes a built-in navigation feature. It also supports over-the-air updates – a real benchmark for user-friendliness. With a Flow+ subscription, you can unlock additional features like eBike Alarm, Battery Lock and eBike Sharing. As for the display setup, many brands pair the SX with the minimalist System Controller. The simple yet functional interface integrates neatly into slim frame designs, helping keep things tidy and intuitive on the cockpit front.
| Parameter | Our measurement | Manufacturer’s spec |
|---|---|---|
| Motor weight (kg) | 2.058 kg | 2,0 kg |
| Battery capacity (nominal, Wh) | 396 Wh | 400 Wh |
| Charge time (0–100%) | 3 h 3 min | – |
| Support ratio (%) | – | 400 % |
| Max power output (W) | – | 600 W |
| Max torque (Nm) | – | 60 Nm |
| Range* (km) | 17.8 km | – |
| Vertical range* (metres climbed) | 1,413 hm | – |
*All values were measured on the same test track with an average incline of 8.5%, using the maximum support mode, a consistent rider output of 150 watts, rider weight of 72 kg, and standardised tyres: MAXXIS HighRoller (DD, MaxxGrip) up front and MAXXIS Minion DHR II (DD, MaxxTerra) on the rear.
Bosch Performance Line SX on test – High-cadence motor
The Bosch Performance Line SX on the trail
With 600 watts of peak power, the Bosch Performance Line SX offers a level of power rarely seen in the light eMTB segment, clearly surpassing rivals like TQ (350 W) and FAZUA (450 W in overboost mode) – at least on paper. This makes it all the more surprising that the SX struggles on steep, technical climbs.
Here, the SX shows two very different sides. When starting off from a standstill on steep inclines, it requires plenty of your own leg power before the motor kicks in – and that’s despite the increased torque of 60 Nm. And even then, the support comes on rather gently, which saps your energy and undermines confidence. Only once you’ve gained some momentum and increased your cadence does the motor deliver steady, punchy support that nearly reaches full-power territory. But that’s exactly where the challenge lies on technical climbs: modulating that power is no easy task. At higher cadences, the power is definitely there, but it’s hard to apply it with finesse. Precise manoeuvring over obstacles becomes difficult at those higher pedalling speeds, even though the motor’s overrun is well tuned. At lower cadences, you have better control of the bike, but the SX noticeably lacks the grunt needed to conquer steeper sections. Compared to its direct competitors – TQ, FAZUA and maxon – the Bosch SX is also noticeably louder on the trail.
In “normal” riding conditions – think forest tracks and mellow climbs – the SX is predictable and delivers a sporty ride feel , giving you noticeably more uphill speed than the TQ and FAZUA drives. When riding in a group alongside full-power eMTBs, a quick downshift into an easier gear lets you make up for the lower torque with higher cadence, allowing you to keep pace with the big motors.
The Bosch Performance Line SX on the test bench
Note: The lab tests were carried out before the Performance Update was released.
In our lab work, the Bosch SX landed bang in the middle of the test field in terms of efficiency – nothing spectacular, but nothing disastrous either. However, its derating behaviour raised eyebrows: after just six minutes, the motor began to noticeably reduce power output. From there, the power remained consistent for a while, before dropping again around the 27-minute mark. The only motor to dial back power even sooner in our test was the Bosch CX-R.
When it came to uphill speed on a simulated 15% gradient with a rider input of 250 watts, the Bosch SX barely edged ahead of the FAZUA Ride 60. That’s reflected in the motor output figures at various rider power levels. At a cadence of 75 rpm, the Bosch SX delivered support very similar to the FAZUA Ride 60.
This highlights one key point: you’ll only benefit from the SX’s higher peak power if you adopt a sporty, high-cadence riding style. Bosch themselves quote a maximum motor output of 400 W at 70 rpm. As for the claimed 55 Nm of torque, we were only able to measure 42 Nm. That shortfall might be explained by the high dynamic setting used in the motor configuration and the fluctuating rider power input in this test setup, which varied by as much as ±80%. In our noise analysis, the SX stood out as having a noticeable tonal quality, and was one of the loudest motors riding uphill, reaching a distinct noise peak around the 600 Hz frequency range.
Tuning tip for the manufacturer: Better responsiveness when setting off on steep climbs would be helpful.
Who should take a closer look at the Bosch Performance Line SX? – and who should look elsewhere?
The Bosch SX motor is the right choice for anyone who prefers lightweight bikes and wants to benefit from Bosch’s extensive, reliable ecosystem. It also suits sporty riders who still want to be physically challenged despite riding an eBike. If you’re willing to put in a bit more physical effort and can do without the shuttle feeling, the Bosch Performance Line SX is a good option – provided you pedal at reasonably high cadences to compensate for the lower torque compared to the CX.
For fans of technical climbs, its character is less suited to setting off from a standstill and lacks more precise modulation. If that’s your main focus, you’re unlikely to find the ideal partner in the SX. Outside of these extreme situations, however, it proves to be a predictable, powerful and fun motor – especially on forest tracks and for everyday trail scenarios. Combined with the rarely used but available 600 Wh battery options, it’s also a great choice for long tours.
Conclusions about the Bosch Performance Line SX
The Bosch Performance Line SX strikes a solid balance between a low system weight and strong support when ridden with a sporty style. It demands plenty of rider input, rewards high cadences with a powerful punch, and reflects Bosch’s vision of active rider engagement.It delivers solid support when pushed, integrates well into the Smart System, and benefits from Bosch’s global service network. However, on technical climbs, the SX clearly shows its limitations, lagging behind its direct competitors despite the higher peak output, and ultimately ranking in the lower half of our test field.
Tops
- Good power-to-weight ratio
- Rewards an active,powerful riding style
- Part of the Bosch ecosystem
Flops
- Behaviour when setting off from a standstill on on steep terrain
- Less seamless integration than the competition
- Louder than the competition
- Early derating
You’ll find all further information on the Bosch website.
The test field
For an overview of the test field head to Our big eMTB Motor Comparison – 15 eMTB Motors on Test
All motors in test:
Avinox M1, Bosch Performance Line CX Gen5, Bosch Performance Line CX-R, Bosch Performance Line SX, FAZUA Ride 60, Mahle M40, maxon Air S, Pinion MGU E1.12, Shimano EP801, S-Works 3.1, TQ HPR60
Words: Lars Engmann Photos: Peter Walker
