RS

Germany's home-grown heavyweight: the Sachs RS pairs ZF's headline 112 Nm with 898 W of measured peak power on Velomotion's dyno — second only to the TQ HPR120S — wrapped in an unapologetically aggressive delivery.

RS eMTB motor — The Sachs RS mid-drive, photographed for Velomotion's 2023 adaptive-update test.

A torquey low-cadence character that hits hardest just off the line and through the mid-range, then tapers as cadence climbs past 90 rpm.

The verdict

Sachs RS is the motor that arrived to out-muscle everyone. On Velomotion's 2022 test bench it punched out a measured 898 W of peak power, second only to the lightweight TQ HPR120S (1,034 W) and just ahead of the Panasonic GX Ultimate Pro (887 W) — leaving the Bosch Performance CX (745 W) and Shimano EP8 (666 W) well behind. ZF's own headline figures are 112 Nm of torque and 700 W of motor power (held for up to three minutes), atop the 250 W EU-continuous rating. However you read the numbers, this is one of the most physically forceful mid-drives ever fitted to an eMTB.

The character matches the numbers. Stamp on the pedals in a low gear and the RS hits so hard the front wheel can lift off the ground unprompted. The original software made that punch feel binary and slightly unruly; the 2023 adaptive update transformed it, replacing the fixed upper support levels with algorithm-driven modes that read speed, cadence and rider torque to dose the power far more intelligently. Post-update, the same raw shove arrives with proper modulation in technical terrain.

The compromises are weight and thirst. At 3.5 kg it is one of the heavier units here, and on the bench it posted the highest energy consumption in Velomotion's nine-motor field — thirstier than even the 1,034 W TQ — both on the flat and on a 10% climb. It is also one of the louder motors under load, with a clearly perceptible hum on long ascents that the testers called uncomfortably loud at high power. Paired with the 630 Wh BMZ pack that Nox fit, or the larger 725 Wh battery on the Storck e:drenalin SRS, that appetite is something to plan rides around. You buy the RS for the firepower, and you pay for it at the battery and on the scales.

“898 watts on the dyno — second only to TQ — and a punch that lifts the front wheel before you've asked it to.”

Character

Rider input

Velomotion drove it at a firm 250 W rider input for its 898 W peak; even a moderate 100 W push still returned around 735 W on the same bench, so it gives a lot back for relatively little. ZF and Sachs publish no support-ratio figure, so there is no official assist percentage — the RS is configured through four named support levels (plus the 2023 adaptive modes) rather than a fixed multiplier.

On the trail

Raw, muscular and eager to lift the front end; the 2023 adaptive software update tamed the worst of its on/off abruptness, turning brute force into something you can actually meter through tricky terrain.

Noise

No lab dBA figure has been published for the RS by ZF, Velomotion or ebike-lab, so we won't invent one. Qualitatively it is among the loudest mid-drives Velomotion tested: a clearly perceptible hum across all support levels that the testers called uncomfortably loud at high load — distinctly noisier than the near-silent Shimano EP8 and the quiet Bosch Performance CX, and noticeably louder than the Brose Drive S Mag's belt-driven hush. It does stay quiet and rattle-free on descents.

Efficiency

The thirstiest motor in Velomotion's nine-drive 2022 comparison, consuming the most energy both on the flat and on a 10% climb — more even than the higher-output TQ HPR120S. Velomotion published the ranking rather than exact Wh/km figures for the RS, but the practical message is clear: this is a motor you size the battery around. Nox pair it with a 630 Wh BMZ pack and Storck fit a 725 Wh battery on the e:drenalin SRS specifically to give the RS the range its output demands.

The case for and against

Strengths

898 W measured peak — second only to the TQ HPR120S in Velomotion's nine-motor test
Headline 112 Nm torque from ZF
Huge, front-lifting low-end punch
2023 adaptive update vastly improved modulation
Returns ~735 W for a modest 100 W rider input

Compromises

Heavier unit at 3.5 kg
Highest energy consumption in the test field — plan the battery around it
Clearly audible, sometimes uncomfortable hum under climbing load
Limited independent thermal/de-rate data; production wound down, parts harder to source

How it stacks up

On Velomotion's 2022 dyno the RS placed second on peak power at 898 W — below the TQ HPR120S (1,034 W) but narrowly ahead of the Panasonic GX Ultimate Pro (887 W), and comfortably above Bosch Performance CX (745 W), Shimano EP8 (666 W) and the Brose Drive S Mag (712 W). Its 112 Nm torque headline beats the 85 Nm class of Bosch and Shimano on paper, but it trades that for more weight and the highest energy consumption in the field.

OWNER INTELLIGENCE

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Sources: ZF Micro Mobility — Sachs RS drive unit datasheet (112 Nm / 700 W / 3.5 kg / 48 V) · Velomotion — E-MTB motors 2022, Sachs RS (898 W peak, 735 W at 100 W input) · Velomotion — E-MTB drives 2022, nine-motor comparison (peak-power ranking) · Velomotion — Sachs RS adaptive software update test (2023).

Bikes running this motor · 1

Nox

Hybrid All-Mountain 2025