Bosch Smart System Mysteries Explained Once And For Good!

[Stefan Mikes]

I have just watched an extensive video from a Bosch E-Bike expert (in Polish) and he explained everything.

Assistance Modes
Overall, there are 13 Bosch Smart System assistance modes. Exceptions:

• SPRINT is only available for SX motors. This mode prefers a high cadence.
• CARGO is available for Cargo motors. This mode provides up to 400% Assistance and slow/smooth acceleration on each ride start.
• RACE is only available for Race motors. It is the mode for powerful Bosch Gen 5 motors to give the e-MTB rider a brutal assistance on racing
• LIMIT is available for S-Pedelecs (45 km/h or 28 mph e-bikes). It limits the speed of the e-bike to the EU 25 km/h.

Assistance modes can be:

• Standard
  • OFF
  • ECO
  • TOUR
  • SPORT
  • TURBO
• Dynamic
  • TOUR+
  • SPRINT
  • eMTB
• Adaptative (only SX/CX modes listed here)
  • AUTO
  • ECO+

Assistance
The rider's leg power input is multiplied by Assistance factor to produce the output motor power. It has nothing to do with the Maximum Motor Power.

Standard Modes (Linear Assistance)
The Assistance factor is fixed for each mode:

• ECO: 60%
• TOUR: 140%
• SPORT: 240%
• TURBO: 340%

The motor power increases linearly with the increased rider's leg power!

The expert explained the Standard modes were his favourites as those left no doubt what the assistance really was, so planning the battery range would be easy.

Expert: "The Standard modes increase the motor power based on the cyclist leg power increase in the linear manner. What to do if ECO is too weak but Tour is too strong? Get into the Flow App, click on the Assistance Mode name and go to Assistance. You can increase assistance: +1, +2, +3... or decrease it: -1, -2, -3... Each increment or decrement means 10%! Say you are in 140% TOUR. Set -4 and your assistance has been reduced to 100%".

Dynamic modes (Nonlinear Assistance)
The assistance in TOUR+, eMTB and SPRINT means a steep motor curve. Whenever the rider increases the leg input power, the motor increases its output very steeply! Meaning, Dynamic modes reward the rider's effort but are heavy on the battery use.

The SPRINT mode is unique to SX motor. It rewards a high cadence. Pedal slowly and you'll get a little assistance. Pedal as fast as Lance Armstrong and you will get the MAXIMUM motor power.
SPRINT is the only SX mode to get to the absolute max power of the motor.

Expert: "Hey, e-gravel cyclist! See a steep hill ahead? DOWNSHIFT then start pedalling fast like a madman! The e-bike will literally lift you onto the summit!"

Adaptative modes

• ECO+ is to conserve the battery charge. Ride on the flat in light terrain and the motor won't even engage! Enter a hill; the motor starts working! You do not need to switch between ECO and OFF on the ride!
• AUTO is the most advanced assistance mode. It is detecting a constant speed of the e-bike and adjusting the assistance to maintain that speed. Start the climb: the assistance will increase. Get a headwind: the assistance will increase, too. All to help the rider maintain a constant speed. Not the most economical of the modes.

Range Control
After 7 years (since Specialized had Smart Control), Bosch introduced Range Control
Go to Flow App. Go to Navigation. Define the route. Define the Battery % remaining post ride. The assistance will be automatically controlled, so you are guaranteed to reach your destination still on the battery.

Dynamics and Speed
The expert didn't discuss those matters at all as they were non-essential.

 

[stompandgo]

Thanks, Stefan. It's nice to have a bunch of info all in one place.

So according to this guy, can each mode be adjusted by cadence or torque throughout the mode range? I see that each mode's assistance can be changed in +/- percent increments, but what if you want to adjust only a section of the mode, i.e. the low end or the top end?

 

[fooferdoggie]

I have just watched an extensive video from a Bosch E-Bike expert (in Polish) and he explained everything.

• ECO+ is to conserve the battery charge. Ride on the flat in light terrain and the motor won't even engage! Enter a hill; the motor starts working! You do not need to switch between ECO and OFF on the ride!
• AUTO is the most advanced assistance mode. It is detecting a constant speed of the e-bike and adjusts the assistance to maintain that speed. Start the climb: the assistance will increase. Get a headwind: the assistance will increase, too. All to help the rider maintain a constant speed. Not the most economical of the modes.

Range Control
After 7 years (since Specialized had Smart Control), Bosch introduced Range Control
Go to Flow App. Go to Navigation. Define the route. Define the Battery % remaining post ride. The assistance will be automatically controlled, so you are guaranteed to reach your destination still on the battery.

myself I cant see a need for range control I want assist at a level that feels good for my energy that day. I want to use as little assist battery % has little to do with it. but that's just me.

 

[stompandgo]

Sounds like you should use ECO until you need a little more. That's what I do (BES2, no adjustment capability).

 

[Stefan Mikes]

So according to this guy, can each mode be adjusted by cadence or torque throughout the mode range? I see that each mode's assistance can be changed in +/- percent increments, but what if you want to adjust only a section of the mode, i.e. the low end or the top end?

According to that man (who also had spoken with a Bosch insider to fully explain Auto) all you do is manipulating Assistance. He showed how to increment/decrement Assistance and explained the numbers. There is nothing like Torque or Cadence in the Assistance section. Perhaps (and possibly!) advanced features can be found in the subscription version. Dynamics was not explained. The guys said there was an MTB setting that allowed the motor propel the e-bike for a distance without pedalling (Extended Boost): sometimes, you need to pass a very short gnarly segment without the danger of a pedal strike. I'm sure the setting belonged to Dynamics, as Specialized has something similar in Levo 4. Such features are usually reserved for e-MTBs and do not need to be available for most motors.
-----------------------------
Once, @Catalyzt showed a Bosch picture in which a rider pedalling at a cadence => 100 could achieve the full boost of an SX motor. That was related to the SPRINT mode of the SX motor.

The Polish YT channel is named dr-ebike. I will watch it more. The person is extremely competent: he could properly describe the properties of a Specialized e-MTB motor and compare it to the CX!

P.S. @stompandgo: the man said 9 Bosch modes were pertaining to any Bosch E-Bike motor and your Bosch dealer could install these modes for you.

 

[stompandgo]

The BES2 speed pedelec motors like mine (BDU490P) are not allowed to have dynamic modes like the "+" modes on the BES3. It's not an option that can be installed, according to Bosch. I believe that they did allow some kind of tuning for these motors via subscription, but that has been shut down by Bosch. The only dynamic mode for BES2 that I'm aware of is eMTB, but this is not supported by my motor. I think it has to do with EU regulations.

It's OK, I'm happy riding in mainly modes 1 (Eco) and 2 (Tour). I did plan a future ride that includes dirt roads, which is the only way to stay off of the state highway towards the tip of the Cape. I may need more assist for those, but who knows at this point. I have plenty of battery.

 

[Jeremy McCreary]

It's OK, I'm happy riding in mainly modes 1 (Eco) and 2 (Tour). I did plan a future ride that includes dirt roads, which is the only way to stay off of the state highway towards the tip of the Cape. I may need more assist for those, but who knows at this point. I have plenty of battery.

Depends on how much tire sinkage and vibration your dirt road produces. If little or none, you may well not need more assist.

In the 3rd or 4th edition of Bicycling Science, Wilson et al. presented some data showing that smooth hardpack adds little rolling resistance over smooth pavement for the same tires. Don't recall the tires tested but probably road tires of some kind.

This matches my own experience on my hybrid Pathfinder Pros with their center slicks. With no sinkage and no bumps, the small side lugs never engage.

Sinkage and vibration (e g., washboard in the extreme case) are the biggest sources of offroad rolling resistance. Eliminate those factors, and it's pretty easy going.

 

[Stefan Mikes]

The only dynamic mode for BES2 that I'm aware of is eMTB, but this is not supported by my motor. I think it has to do with EU regulations.

Nah. It is the policy of Bosch to provide different solutions to different purpose motors (such as e-MTB, a commuter or e-gravel). The only regulatory matter is the S-Pedelec (which has several restrictions as Bosch has never realised the U.S. were not Germany).

Specialized also makes some difference between e-MTBs and more regular e-bikes. Specialized e-MTBs are tuned to a quite different motor curve than regular e-bikes. Several options are only found in Spec e-MTBs, such as Acceleration, Shuttle Mode or Dynamics. Not that differently from Bosch!

 

[peterh_nz]

I believe that they did allow some kind of tuning for these motors via subscription, but that has been shut down by Bosch. The only dynamic mode for BES2 that I'm aware of is eMTB, but this is not supported by my motor.

Yes, on BES2, a small one off payment allowed the creation of four custom assist profiles inwhich one can change the level of assist at any point throughout the speed range. Bosch stopped the ability to purchase the customisation but, for those who had purchased, the customisation function still works.

As my "mode" of riding is for exercise, I set the four custom levels as: 60% Eco, Eco, mid Eco-Tour, and Tour. Have used these custom modes over most of 22,000km. Maybe once every couple of months I'll temporarily hot switch back to the standard levels of assist, mainly for the novelty!

I have the speed model and back in 2020 I elected not to have the eMTB mode implemented.

 

[peterh_nz]

Other very good summaries of Bosch modes and assist levels:

Bosch Assistance Modes Explained - Freeborn Bikes

Bosch Assitance Modes Explained

www.freeborn.co.uk

and

https://www.bosch-ebike.com/en/products/riding-modes

 

[Catalyzt]

This is super helpful... but has a few omissions, and a few things don't seem quite right. There are a few things I have to think about more, but...

Standard Modes (Linear Assistance)
The Assistance factor is fixed for each mode:

• ECO: 60%
• TOUR: 140%
• SPORT: 240%
• TURBO: 340%

To this, we can add:

* SPRINT: 280% (per Bosch documentation.)​

​

This is why, on the sx, Sprint is probably a great substitute for Sport for fitness riding: It provides a bit more assistance, but encourages you to be doing everything right (high cadence) before you use the battery-draining Turbo. I suspect that it may be more efficient when it's providing, say, 160% assistance because it won't give you more unless you need it, but there is no way to be sure.

However, this contradicts the statement:

SPRINT is the only SX mode to get to the absolute max power of the motor.

It seems like Turbo provides more power at 340% compared to 28% for Sprint. Also, Race (when available, it's not on my bike and I don't need it) provides 400% assistance.

I would LOVE to have ECO+ but I do not. Maybe the dealer can install it? I can't see why it would be forbidden on a gravel bike, or by Canyon, but who knows?

Dynamics and Speed
The expert didn't discuss those matters at all as they were non-essential.

Really?! Dynamics seems to address how much leg torque & cadence is needed for the mode to start providing assistance. I'd love to know more about that-- If there is a gap in power, do I want to add more assistance to Eco, or decrease the dynamic on Tour?

Speed is also very interesting. Theoretically, it seems like you can set it to 20 MPH, effectively converting your Class III to a Class I. Wouldn't it be amazing if the bike had a 'Class 1" mode, complete with a readout of how long, and where, it was turned on?

If you got pulled over by the trail warden, you could show him the readout. "Thank you, sir, I see you've been limited to 20 MPH since the trailhead. You are free to go, and so is your bike."

 

[stompandgo]

Nah. It is the policy of Bosch to provide different solutions to different purpose motors (such as e-MTB, a commuter or e-gravel). The only regulatory matter is the S-Pedelec (which has several restrictions as Bosch has never realised the U.S. were not Germany).

My drive unit is a speed pedelec motor. System 2 Performance Line Speed. It has nowhere near as many options as other drive units in the diagnostic.

 

[stompandgo]

Yes, on BES2, a small one off payment allowed the creation of four custom assist profiles inwhich one can change the level of assist at any point throughout the speed range. Bosch stopped the ability to purchase the customisation but, for those who had purchased, the customisation function still works.

As my "mode" of riding is for exercise, I set the four custom levels as: 60% Eco, Eco, mid Eco-Tour, and Tour. Have used these custom modes over most of 22,000km. Maybe once every couple of months I'll temporarily hot switch back to the standard levels of assist, mainly for the novelty!

I have the speed model and back in 2020 I elected not to have the eMTB mode implemented.

I missed the shutdown by two weeks. Really ticks me off.

Bosch said that eMTB cannot be installed on my drive unit. Other Class 3 ones can, though.

 

[peterh_nz]

I missed the shutdown by two weeks. Really ticks me off.

Yes, that would be annoying. I guess Bosch decided anyone with the "old" system, if they intended, would have purchased the custom option well before the cut-off date. But then, why cancel it anyway?

 

[Gionnirocket]

The guys said there was an MTB setting that allowed the motor propel the e-bike for a distance without pedalling: sometimes, you need to pass a very short gnarly segment without the danger of a pedal strike.

THROTTLE

 

[stompandgo]

Yes, that would be annoying. I guess Bosch decided anyone with the "old" system, if they intended, would have purchased the custom option well before the cut-off date. But then, why cancel it anyway?

Especially when there are still a ton of BES2 bikes for sale new on closeout. How much did that "server" actually cost them? My guess, peanuts. This is Bosch not just planning obsolescence, but actively forcing it.

 

[Catalyzt]

THROTTLE

When I saw that feature listed, I KNEW one of y'all was gonna give a Bronx cheer and start razzing us mid-drivers about throttles!

Shoulda figured it would be you!

 

[Stefan Mikes]

To this, we can add:

* SPRINT: 280% (per Bosch documentation.)

Yes. I omitted that mode as unique to the SX motor only. Same, I omitted RACE, CARGO and LIMIT as specific to some motors.

It seems like Turbo provides more power at 340% compared to 280% for Sprint.

Remember that picture you showed some time ago that showed you needed cadence 100 or greater to get the full boost of the SX? This requires further investigation!

Dynamics seems to address how much leg torque & cadence is needed for the mode to start providing assistance.

I simply wouldn't meddle with the Dynamics, as that is the easiest way to misconfigure already nicely set presets.

I'd love to know more about that-- If there is a gap in power, do I want to add more assistance to Eco, or decrease the dynamic on Tour?

Manipulating the Assistance is sufficient and straightforward imho. Why not to just decrease the Assistance on Tour?

If you got pulled over by the trail warden, you could show him the readout. "Thank you, sir, I see you've been limited to 20 MPH since the trailhead. You are free to go, and so is your bike."

You might disagree with me but a Class is a property of a vehicle not any artificial setting. Think of Type Approval for motorized vehicles.

Other very good summaries of Bosch modes and assist levels:

Bosch Assistance Modes Explained - Freeborn Bikes

Bosch Assitance Modes Explained

www.freeborn.co.uk

and

https://www.bosch-ebike.com/en/products/riding-modes

Thank you!

 

[Gionnirocket]

When I saw that feature listed, I KNEW one of y'all was gonna give a Bronx cheer and start razzing us mid-drivers about throttles!

Shoulda figured it would be you!

Don't kid yourself... I have a mid_drive.
But it's a 1000w / 160Nm with no speed restrictions. Aka: mid_drive for adults

 

[Stefan Mikes]

@Catalyzt: I have studied more material available online.

Dynamics (Acceleration)
This parameter controls how fast the e-bike accelerates at the ride start: More brutally or smoother. More Acceleration means more battery use, especially on frequent starts/stops.

Max. Torque
It manipulates the motor power curve at low cadence. It is a feature useful in e-MTB. In a scenario of restarting the pedalling against a rock on a gnarly trail, the rider needs a lot of oomph at very slow rotation of the cranks. This feature is purely Mountain Biking related and is of no use on a gravel e-bike.

Neither feature is related to power bands, which are to be controlled by Assistance.

Max. Speed
It is not meant for changing the e-bike Class but for the battery charge saving. Your Grizl is a 28 mph e-bike (isn't it?) If you are a good pedaller, you can easily ride your drop bar e-bike assisted at, say, 22 mph on asphalt on the flat. However, the idea of Bosch is you could use the assistance for low speed scenarios (climbing or countering a massive headwind) but ride on the leg power at a higher speed. If you set the Max. Speed at 16 mph, you will be assisted up that speed but are expected to ride on the leg power only above. No need to use the OFF mode! Ride slower assisted and faster unassisted. This results with huge battery savings!

Bosch would be the last company in the world to encourage e-bike Class manipulation.

Extended Boost (Overrun)
Only available for eMTB mode. The option works for just 1 metre after you have stopped pedalling, and is is definitely not a throttle. Only useful on e-MTBs. Not to be used in urban scenarios at all! Fancy a kid running into the front of your bike on a MUP. You violently brake but the motor still propels the e-bike!

A good video.