It won’t be news to anyone to hear that the Drive T motor from Brose has a lot of fans. The Drive T is loved for its natural power transfer and classic ride sensation. Yet its actual power output has long been a sticking point. That should change now with the launch of the Drive S, which is built around Brose’s revised system relying on 16 new electronic parts and optimized software. As it looks set to sweep its predecessor off the board, we thought it was time to pit these two siblings head to head.

Seen from the outside there’s little to differentiate the former Drive T and the new Drive S from each other, but the newest iteration has a wealth of changes inside.

So what’s new on the Brose DRIVE S?

The brand new Brose DRIVE S has seen the German brand focus on what’s inside, fitting 16 new electronic parts and really getting a handle on the rest of the complex internal parts. It might seem minor but even swapping a steel screw for a stainless steel one on the circuit board has led to efficiency gains of 1.25% on the DRIVE S. Yet way more than just screws, Brose have fine-tuned the inside of the motor meticulously, resulting in a motor with 15% more power and a more economic ride manner. But going beyond purely technical aspects, Brose also turned their hand to improve its heat dissipation by adopting new seals, and looked for ways to improve the motor’s sensory system too.

Old vs New
The series number is the only visual difference. The Drive T goes by C 911, while the Drive S is categorized as C 972.
Fine-tuned heat dissipation should mean higher efficiency and less risk of switching off.
Major advantages of a belt drive – no internal resistance when riding faster than 25 km/h, or when the motor is switched off.
Our test setup
We tested both motors back-to-back from the base in idyllic Aschau i. Chiemgau.

More power whatever the cadence

With 90 Nm torque, the former Brose Drive T always promised to soar ahead of the competition, although its high performance wasn’t hugely notable in our real-world testing as these peaks of output remained brief. The new motor promises a different scenario with more power delivered more consistently over a wider cadence spectrum without any impact on the same natural sensation that it has retained from the original Brose Drive T.

For direct comparisons we mounted the motors alternatively onto a Rotwild R.E+.
Both motors were tested with the standard motor covers.

The Brose Drive S on the ‘Test Bed’, aka the tarmac

While we won’t refute the stats given to us by manufacturers, we definitely recognize that reality has to take precedence in testing. Thanks to support from ROTWILD, we had the exclusive opportunity to pit the Drive T directly against the Drive S on one bike. The testing was pretty straightforward. The bikes had to take on a 650 m long test loop with 82 meters of climbing and a 12% gradient. Using a GARMIN and a power meter we tried our utmost to maintain a consistent 80 pedal strokes per minute and 140 watts from the rider. In terms of our conclusions, we took the mean values from the two most consistent laps, which saw the new Brose Drive S clock 3:06 minutes, a full 20 seconds quicker than the older Brose Drive T.

Motor Rider’s power output Cadence Speed Total time
Brose Drive S 139 Watt 79 rpm 12.65 km/h 3:06.5
Brose Drive T 142 Watt 81 rpm 11.31 km/h 3:27.9
Using a Garmin to measure power and cadence gave us quantifiable stats to compare.

Despite our staged test scenario, it’s clear than the new motor has significantly more power inside it. Pit these results directly against testing that was carried out earlier this spring with models from Bosch, Shimano, Yamaha and Panasonic, and once again the new Drive S appears to possess bags of potential to rival the rest of the market.

As it’s virtually impossible to pedal consistently on multiple loops our data certainly cannot be taken as gospel, and it really just confirms the general trend that the new Drive S is notably more powerful.
Riding the loop with the old Drive T motor took a full 20 seconds longer than with the newer motor.

Riding the new Brose Drive S

As it’s a belt drive, the Brose motors have always had one major trump card: its super natural ride sensation. One worry with the new, more powerful design is that this could get lost in a sea of mechanics, but fortunately, these fears were unfounded! The Drive S works with just as much human sensitivity as the former Brose models. The main performance gains come from its responsiveness and great power delivery even when your cadence slows – this is a major asset on steep, technical climbs. Much like the Drive T, the Drive S still distributes its power in a fairly progressive manner, so don’t expect the full monty as soon as you push down on the pedals.

More power = more battery drained?

Brose motors have always been known for their extensive range. And while the new Drive S is reputed to be even more economic than before, we weren’t able to test this intensively during testing. But if there’s one thing to note: if you’re using a lot of power, then expect to use a lot of energy, right. Riding with full pedal assist for long periods will mean you’ll need to recharge your battery fairly regularly. However, pick your moments and you’ll conquer long rides with the right attitude.

The test bike and the test track: 650 m in length, with a climb of 82 metres.

What’s your take on the reliability of the Brose Drive S motor?

We can’t comment on the durability of this German-made motor so far, but Brose recommend servicing the Drive T model every 15,000 km. They’re still recommending the same interval for the Drive S.

When’s the new motor available?

The new Brose Drive S motor will be fitted onto bikes by the end of this year for models being released in 2018.

The wiring loom and mount remain the same so you can easily upgrade the motors.

Can I upgrade my current E-MTB?

Yep, upgrades are possible. We can’t confirm any prices nor reveal when the upgrades will be possible, but as the mount and wiring loom will remain unchanged, the new Drive S motor may be upgraded onto most current bikes with Brose motors. It can be possible that the battery has to be updated too because the motor is using more energy at some points. Moreover, Brose are planning on developing further software updates for the current Drive T motor in order to render it more powerful and economic.

While unchanged on the exterior, the Drive S has some new, complex, ultra powerful internals.

Our thoughts on the new Brose Drive S motor

Respect, Brose! The new Drive S motor delivers significantly more max power while – more importantly! – still conveying that super natural ride sensation. Just as quiet and hush-hush as its predecessor, the Drive S is a real pleasure to ride! Plus, for those who like to go a little quicker from time to time, there’s no tangible resistance above 25 km/h! We can’t wait to test the new motor on some new 2018th bikes.

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