120 Nm update for the Bosch CX and CX Race Announced

[Suns_PSD]

It's activated by pedalling backwards. It only needs a very short impulse (less than a quarter turn) to activate.

Is there an on/ off setting in the app that I missed?

I tried the kick back method and could not get it to work. But it's a useful feature to be able to control without having to hardwire a derailleur.

 

[killerade]

Is there an on/ off setting in the app that I missed?

I tried the kick back method and could not get it to work. But it's a useful feature to be able to control without having to hardwire a derailleur.

 

[Brawwp]

So it picks up any hub slack? I can see this being super useful for climbing, but hasn’t the new trend been to eliminate pedal kickback? Seems this would increase kickback. Would be cool to have one of the accessory buttons be able to activate/deactivate it for climb and descents.

 

[RustyIron]

Had anyone gotten to the bottom of this feature and what activates it?

It's not "activated," and there's nothing to get to the bottom of. The pre-tensioning is happening all the time when you're riding. The motor gives a little torque to take up slack in the drivetrain. Pedaling backwards is just changing the conditions, and the torque on the motor runs everything forward to eliminate slack. Nor is pedaling backwards while shifting some kind of hidden feature. There is no reason to even do that. You can understand the frustration of the manufacturers when users do goofy things with their products that make no sense, and then go around spreading misinformation on the interwebs.

 

[Shark58]

So it picks up any hub slack?

Not only for the hub but also for the two freewheel clutches inside the motor. And if you don't pedal backwards it won't activate which should take care of pedal kickback.

The idea from Bosch is, that after some decent standing on your pedals and then moving into a steep/technical climb you can now get rid of any slack in the drive train or when accelerating out of a corner. The function is clearly targeted towards racing and therefore only available in Race, eMTB and eMTB+ modes.

 

[Brawwp]

Not only for the hub but also for the two freewheel clutches inside the motor. And if you don't pedal backwards it won't activate which should take care of pedal kickback.

The idea from Bosch is, that after some decent standing on your pedals and then moving into a steep/technical climb you can now get rid of any slack in the drive train or when accelerating out of a corner. The function is clearly targeted towards racing and therefore only available in Race, eMTB and eMTB+ modes.

How is pedaling backwards any better than pedaling forward to take the slack up though? Or how long would it tension I guess? If you are descending and coming up on a climb it seems easier to just pedal forward than getting a backward pedal in. You sure it’s not just always tensioning when on?

 

[Shark58]

It's not "activated," and there's nothing to get to the bottom of. The pre-tensioning is happening all the time when you're riding.

Bosch does not agree with you:

Why has the chainring been turning forward when I pedal backward since the latest update?​

This is the visible result of the Drivetrain Tensioner. This offers added value, especially to performance eBike riders who expect direct, instantaneous traction. The Drivetrain Tensioner ensures direct response behavior, especially with a dynamic riding style, frequent load changes, and on technical terrain.

In eMTB, eMTB+, and Race riding modes, the chainring moves slightly forward when you pedal backward. This process pretensions the drivetrain and closes the freewheel. The benefit for you: As soon as you start pedaling again, you'll have immediate traction.

This behavior might feel a little strange to you at first.

Source: Help Center - Bosch eBike Systems | Help Center

 

[Shark58]

You sure it’s not just always tensioning when on?

It is not.
There is a video from mister uphill flow Stefan Schlie who helped develop this. He demonstrated the feature and said, that after a decent most riders automatically do a short backwards pedalling before pedalling forward. He showed less than a quarter turn to activate the chainring.

 

[Brawwp]

It is not.
There is a video from mister uphill flow Stefan Schlie who helped develop this. He demonstrated the feature and said, that after a decent most riders automatically do a short backwards pedalling before pedalling forward. He showed less than a quarter turn to activate the chainring.

But where are you seeing you have to backpedal? I can’t find that and it seems Bosch would put that out on how to activate it. I’m thinking you guys backpedaling is just making it try to pick up more slack and you’re seeing it tensioning, but it was already tensioned before you backpedaled.

 

[crisillo]

But where are you seeing you have to backpedal? I can’t find that and it seems Bosch would put that out on how to activate it. I’m thinking you guys backpedaling is just making it try to pick up more slack and you’re seeing it tensioning, but it was already tensioned before you backpedaled.

In the link he posted above.

 

[Brawwp]

In the link he posted above.

View attachment 188344

Oh duh. Interesting. Pedaling forward seems like it’d do the same, but I guess I’ll be interested to see how you guys like it.

I was thinking it was just always tensioned when on which could be cool if you could click a button to deactivate it. Then you could run kickback hubs for free feeling dh then activate it coming up to uphill techy sections. Having to think about backpedaling seems odd to make this work.

 

[crisillo]

Oh duh. Interesting. Pedaling forward seems like it’d do the same, but I guess I’ll be interested to see how you guys like it.

I was thinking it was just always tensioned when on which could be cool if you could click a button to deactivate it. Then you could run kickback hubs for free feeling dh then activate it coming up to uphill techy sections. Having to think about backpedaling seems odd to make this work.

the idea is that most people do it unconsciously when moving from the 3/9 o’clock pedal position used while descending to move to a oedal position

 

[Suns_PSD]

Bosch does not agree with you:

Why has the chainring been turning forward when I pedal backward since the latest update?​

This is the visible result of the Drivetrain Tensioner. This offers added value, especially to performance eBike riders who expect direct, instantaneous traction. The Drivetrain Tensioner ensures direct response behavior, especially with a dynamic riding style, frequent load changes, and on technical terrain.

In eMTB, eMTB+, and Race riding modes, the chainring moves slightly forward when you pedal backward. This process pretensions the drivetrain and closes the freewheel. The benefit for you: As soon as you start pedaling again, you'll have immediate traction.

This behavior might feel a little strange to you at first.

Source: Help Center - Bosch eBike Systems | Help Center

So this makes sense. I was riding with a good friend that was on an SL e-bike and as such I kept my Bosch in Tour+ mode for yesterday's ride. Sounds like the DT feature isn't available in the mode I was using most of the time.

I figured it was either the mode I was using, or possibly Bosch only activates it above a certain speed, now I have my answer.

I cheated a handful of times using my 4 week old knee surgery as my built in excuse, and I guess that's when I saw it working.

It wasn't just 'taking up a little slack', that front chain ring spun around 2 full rotations with my own eyes.

 

[Shark58]

Check the video with Stefan Schlie and Danny MacAskill testing all the new Bosch features. There is a very short chapter on drivetrain tensioner.