Bosch Performance SX first ride review

My first factory built emtb was a 2013 Cannondale Tramount 1. That was a hardtail with a Bosch Performance 60 Nm motor and a 400 Wh external battery. And now, 10 years later, it seems we’ve come full circle. The new 55 Nm Bosch Performance SX has about the same torque and battery capacity. But the size and weight are completely different. The motor and battery weighs about 2 kg each. See the video below for all the details and an illustration of motor behavior. Or keep on reading.



The CompactTube 400 battery​

Years ago, I asked, when will we stop seeing bigger batteries? When will progress in battery tech result in more lightweight bikes, not constantly increased range? The lightweight emtbs are the answer to my questions. Bosch made a new and properly lightweight 400 Wh battery. It’s got the same number of cells that the usual 360 Wh batteries, but the battery cells are ever so slightly larger.

The result is just over 10% improved capacity and a minor weight increase. It weighs just 2 kg, the 360 Wh batteries usually are between 1.8 and 2 kg. And equally as important, the battery is more powerful, allowing it to deliver more current to the motor.

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Bosch Performance SX​

And the motor knows how to take advantage of the increased current capacity. 55 Nm motor torque isn’t extraordinary. But combine that with a high pedaling frequency and you still get lots of power. Bosch rate the Performance SX at 600 watts max, available when pedaling at above 100 rpm.

This 2 kg motor is more compact than the Performance CX, making it easier designing sleek looking frames. The motor isn’t as compact as some other mild emtb motors though. While some can be hidden completely inside the frame, the SX will likely be visible on the upcoming bikes.

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On the lightweight emtbs, we get the usual Turbo, EMTB, Tour+ and Eco modes. But this motor has been made for gravel bikes too. Those will have the EMTB mode replaced with a new Sprint mode. Sprint is programmed to inspire you to maintain a high cadence, potentially providing maximum motor power for much of the ride. There will also be a 28 mph version of the motor for the US and New Zealand. But I guess it could be available on the European Speed Pedelecs too?

Bosch Performance SX

The Bosch Performance SX was developed with gravel ebikes in mind too.

PowerMore 250 range extender​

A 600 W motor can of course be “thirsty”. Adding the new 1.6 kg range extender brings capacity up from 400 to 650 Wh, that should go a long way on a lightweight emtb. The motor will draw power from both batteries simultaneously, which is a good idea. That way, the batteries share the load, resulting in lower heat loss and improved efficiency.

The Paramore, I mean PowerMore 250

The Paramore, I mean PowerMore 250

Bosch Performance SX on the trails​

Several full power emtb motors are rated at 600 W or less. Does that mean the Performance SX is more powerful? When pedaling fast, it should be. But it’s noticeably weaker at lower cadences. It feels less like a free ride. Entering the foot of a climb in a slightly to high of a gear, it won’t power you up like the full fat motors do. But if you pick the correct gear ratio, the SX motor still offers a nice amount of help. For those that rarely ride maximum assistance, this doesn’t feel like much of a step down.

Bosch Performance SX going uphill


Using the Bosch Flow app, I set the Turbo mode power to +4. It’s set to 0 by default and can be adjusted between -5 and +5. The motor remained easy to control when starting and stopping in technical sections. It’s not the ultimate motor for riding challenging trails with max assistance, it can be a tad twitchy. But Turbo mode was fine in these dry conditions, I never felt the need to reduce the power.

Dropping to EMTB mode significantly improves motor control though. There is no trace of twitchiness, it’s such a well-behaved motor. There’s still a decent amount of power in Tour+ mode, but it didn’t feel easier to control compared to EMTB mode. Eco mode feels very stingy. See the video above for more details on motor behavior.

Bosch Performance SX on a somewhat technical climb


Compared to other mild emtb motors​

Speaking of stingy. I’ve been putting these mild emtb motors in two categories. One is motors such as the TQ HPR50 and Fazua Ride 60. These are “stingy” motors that requires you to put some force on the pedals to get the most out of the motor. You can’t spin the pedals lightly and expect a free ride on climbs and transport sections. This makes the motors natural feeling and they consume less energy from the battery.

Then there’s the “generous” mild emtb motors, like the Shimano EP8-RS and the Forestal EonDrive. These are very powerful at lower cadence, possibly matching the full power motors, but they drop off as cadence increases. Also, they are noisier motors that are more visible in the frame. They don’t offer the same stealthy experience as the stingy motors do.

Bosch Performance SX


Even though the Performance SX doesn’t offer the same low cadence power as the mentioned motors in the “generous” category, it still belongs there. For a mild motor, it does have a good amount of power down low. And the SX doesn’t offer that stealthy riding experience. Also, it is very powerful once you get going and the cadence picks up. I still haven’t ridden the Specialized 1.2 motor, so I don’t know how that compares.

Noise​

The “stingy” motors can be inaudible, the Bosch Performance SX is not. We couldn’t do a side-by-side comparison with other motors, but my initial impression is the SX is slightly less noisy than the CX. It could just be that the SX is a brand-new motor, noise levels could go up as the motor wears.

This unknown bike model has the chargeport up high.


Pedaling calmly at lower cadence, I didn’t notice much noise. As cadence increased, so did the noise. Still, noise levels are far from bad. Coasting on the descents, there is a bit of motor rattle, just like on the CX. I would say the SX rattles less, but who knows, that could change with time. Check out the video above to hear the motor noise.

Conclusion​

When you get 600 W from a mild and lightweight motor, who needs a full power motor? The higher torque of the full fat motors makes a difference. They can be ridden with less effort. But the Performance SX isn’t far behind, and with a more active riding style, it will keep up.

On this particular bike, the handlebar remote was a bit too close to the dropper, making me accidentally drop motor assistance.


For those who also use the lower assistance modes, there isn’t much of a sacrifice going with the SX. The upside is a compact motor that requires fewer compromises for frame design. And it’s about 30% lighter than the full power motors. I’m expecting lots of interesting bikes to be launched shortly, and Bosch says Performance SX powered bikes will be in stores this autumn.
About author
knut7
Started mountainbiking in the 90s. Moved to emtbs in 2014 and have been reviewing them since 2016. Contact me here https://emtb.no/contact/

Comments

How does the range extender plug in? Through the charging port? Just wondering how it would connect to existing Bosch Smart System full fat bikes.
 
How does the range extender plug in? Through the charging port? Just wondering how it would connect to existing Bosch Smart System full fat bikes.
Yeah, on this bike there's a port on the side of the seattube. They said these are new "building blocks" for the Smart System, so I'd assume it works with the Performance CX Smart System too. Haven't tested though.
 

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From what I know full fat bikes don't allow for a range extender, at least when it comes to Specialized and Bosch motor emtb's that I have.
 
On paper this motor is promising, though not as discrete as TQ, Fazua and SL.
The extender though... Too bulky, overall shape is poorly designed. Integration was not a priority it seems.
 
Have you ridden the Ride 60 with the latest firmware update? You will not recognize it if you haven’t.
 
Have you ridden the Ride 60 with the latest firmware update? You will not recognize it if you haven’t.
I did not, can you tell us how boost mode functions now. Can you use it continuously (while keep pushing on the button)?
 
No unfortunately boost still seems to work the same. But the overall response of the motor is way better. To be honest I have not fully explored this area. I have been riding my full power bike primarily . Stay tuned
 
What is a realistic weight for this setup in an aluminum bike. Is this possibly a 45lb solution?
 
On paper this motor is promising, though not as discrete as TQ, Fazua and SL.
The extender though... Too bulky, overall shape is poorly designed. Integration was not a priority it seems.
One would think that the lower top of the RE would be slanted to allow more room for a piggy back shock.
 
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