After the Update

Review: Dyname S4 Lite Motor

Rocky Mountain has updated the Dyname 4SL with more power. Does the motor join the full-power league despite the SL model designation? We tested the motor with its unique concept to answer all these questions.

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While almost all manufacturers rely on Bosch, Shimano, or DJI for motor choices, Rocky Mountain has always taken its own path. With Dyname, the Canadians have focused on developing their own brand from the start. Dyname has now even opened up, offering its motor to brands other than Rocky Mountain.

The uniqueness of all Dyname motors: They do not transmit their power over the main chainring as usual, but via an idler directly to the chain. This concept is complemented by a separate torque sensor and cranks that run completely independently of the e-system. Dyname’s promise: an exceptionally direct riding experience without delays or a “moped-feel.”

If you’re interested in the test bike, the Rocky Mountain Instinct Powerplay SL, you’ll find a detailed test report here.

Dyname S4 Lite Motor Test — Rocky Mountain gives its Dyname S4 Lite motor a power update. The Instinct Powerplay SL now plays in the full power league.

Rocky Mountain Instinct Powerplay SL — We tested the updated motor in an Instinct Powerplay SL. Earlier this year, we had this bike on test. The report is linked.

Dyname S4 Lite motor update — Feature: Not only does the motor need an idler pulley to transfer its power to the chain, but the high-pivot suspension also requires this pulley. This way, Rocky kills two birds with one stone.

On the Trail: Direct and Powerful

On the trail uphill, it’s noticeable: The motor responds instantly without unnatural power surges. When you stop pedaling, the support also ends immediately—there’s no overrun like with other systems. This provides a very natural feeling, far from a moped-like experience.

If you’re interested in the test bike, the Rocky Mountain Instinct Powerplay SL, you’ll find a detailed review here.

Dyname S4 Lite Motor Pulley — The upper jockey wheel transfers the power to the chain. The front roller measures the torque applied and provides the motor with information.

Power: How much does the motor deliver after its update?

Despite the “SL” abbreviation, the motor surprises with decent power. Thanks to the update in September 2025, our test showed 490 watts with 150 watts input – significantly more than classic lightweight motors like the TQ HPR 60 or Bosch SX, which deliver only about 360 or 370 watts in the same test. Even at low cadences, the support remains strong, which pays off especially on steep sections. The Dyname 4 SL motor now plays in the full power league.

Dyname S4 Lite motor power — With almost 500 watts at 150 watts input, the Dyname S4 Lite now plays in the full-power league.

Generally, as with almost all motors: with a higher input power and/or higher cadence, the Dyname also delivers more output power. To test this, we have, as always in our motor tests, conducted series of measurements with various input scenarios.

Dyname S4 Lite Motor Cadence — We always conduct our tests with standardized SRM pedals in practice. Various measurements show that the maximum motor power is reached at 90 RPM at the crank.

Dyname S4 Lite Motor Power Delivery — If you increase the input power from 150 to an athletic 250 watts, the motor only delivers 10 more watts of output.

Dyname S4 Lite Motor Experience — With 500 watts, you can enjoy real riding fun even on the Uphillflow trail at Geißkopf.

Efficiency: How much energy does the motor draw from the battery?

Under standardized test conditions on asphalt with a system weight of 100 kg, we achieved 1,375 meters of elevation gain in Ludicrous mode (highest assistance) with the bike. Considering the nearly 500 watts it delivers, that’s impressive—and significantly more than a Bosch SX motor with less power can squeeze out of its 400 Wh battery. In the same test, it managed 130 meters less elevation gain.

And in most cases, SX bikes also come with built-in batteries. This is where the Instinct Powerplay SL (our test bike) truly shines: you can either swap the battery or, for about €500, get a PowerTube pack with an additional 314 Wh. This gives you maximum flexibility when it comes to range. We like that.

Dyname S4 Lite Motor Range — Epic days in the saddle. That's what you want to experience with a bike like the Instinct Powerplay SL. And thanks to many options with the battery, it's possible.

Dyname S4 Lite Motor Efficiency — The range is significantly better than that of Bosch SX bikes with a 400 battery. With 1375 meters of elevation gain in our standardized test at the highest support level with 150 watts input and a system weight of 100 kilos, Dyname doesn't need to hide.

When it comes to sound, the Dyname S4 Lite has two distinct profiles.

What’s awesome about the Dyname-4SL motor: It’s really quiet on the downhill. No gearbox noise like with other motors. However, it can’t be denied: Uphill, the motor makes a bit more noise than a Bosch CX.

You’re more likely on the level of Bosch’s SX motor – and therefore considerably audible. Whether it’s because the chain runs over three cogs instead of one, or if it’s from inside the motor, is hard to differentiate. But the test showed: A well-maintained chain at least minimally reduces the noise. However, you can’t make the motor completely quiet even with some chain oil. By the way, you also need to change the small drive sprocket regularly. Rocky recommends doing this approximately every 5,000 to 10,000 km. Cost: around 80 €.

Gear rattle — Going downhill, the motor is completely silent. Going uphill, it makes a distinctly grinding noise.

Weight Advantage Despite Full-Power Feeling

With 2.3 kilograms, the Dyname 4SL is lighter than the Bosch CX or DJI Avinox – depending on the comparison, by 400 to 600 grams. This is noticeable in the bike’s overall weight, even though the motor now really kicks in.

In practical testing, we conquered 1,000 meters of elevation in 29 minutes – with classic light eMTBs, this often takes 15 minutes longer.

Weight — The motor weighs 2.3 kilograms, forming the foundation for lightweight bikes.

Weight — A weight of just over 20 kilograms is achieved by only a few bikes with a powerful 500-watt motor.

Pros:

direct ride feel
Power update delivers performance at full-power level
Lightweight motor for reduced overall bike weight

Contra:

In-house development: Service & spare parts not as widespread as with Bosch & Co.
Sound: relatively loud uphill

Dyname S4 Lite Update Test — The Dyname S4 lite received a sensible update. We've linked the test for the Rocky Mountain Instinct Powerplay SL in a separate article for you.

For those interested in the test bike, the Rocky Mountain Instinct Powerplay SL, a detailed review can be found here.

Conclusion on the Dyname S4 Lite Motor

After its update, the Dyname 4SL motor is no longer a compromise, but a statement. It combines the weight of a light e-MTB motor with the power of a full-power system – delivering an extremely direct and natural ride. Those who crave an independent concept and can do without standard solutions will find a true highlight here. For mainstream buyers, the motor remains an exotic choice.

About the author

Ludwig Döhl

... has spent more than 100,000 kilometers in the saddle of over 1000 different mountain bikes. The bottom line from many hours on the trail: mountain bikes are awesome if they match your personal preferences! With this insight, he founded bike-test.com to help bikers find their very own dream bike.