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Bosch eMTB mode software update July 2017. Our inside view and pre release review

Words by bike zone oxford

on 22/06/2017 16:25:29

Automatic Support Level Adjustment is coming! Do we need it? Will it help?

bosch emtb crop1

Bosch E-bike systems have revealed they are getting ready to launch a big software update for the eMTB market this July, and manufacturers will have the option to pre-install the software on their own bikes from 2018 onwards.

So what will the new update do? and how will it work? The material from Bosch says ”The eMTB mode replaces the Sport mode of the Performance CX Line and varies between the Tour and Turbo riding modes. With a maximum torque of up to 75 Nm, the motor will dramatically boost pedal power of the rider between 120% and 300% depending on the pedal force and without changing the mode”.

So what will this give us in reality? In short, less clicking and better riding. With the use of all three on board sensors, speed, cadence and torque, all taking a thousand measurements a second combined, the on board electrical brain can think quicker, react faster and more than likely make a better decision for us while we are concentrating on the next obstacle or killer climb up ahead.

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Support Modes on an eMTB

One of the joys of riding any Pedelec bike is that motor assistance is relative to rider input. This makes the rider feel “bionic” and the feel of the whole thing remains remarkably natural as power remains proportional to effort.

Tour Mode

Tour is the mode which most people use a default mode on Bosch systems . The maximum assistance level in this mode is 120% so…

• If a rider is pedalling very casually at say 80W power then the motor will add 1.2*80=96W for a total of 176W, the power of a normal cyclist working rather hard

• If the rider is pedalling briskly at say 150W the motor will add 1.2*150=180W for a total of 330W which really is quite a lot.

In both cases though the support is progressive. Put in more power and the machine adds power in proportion to your input.

Turbo Mode

The highest power mode on the Bosch System offers up to 300% assistance so if we look at the same two light/brisk riding scenarios as with Tour we get:

• For the casual rider inputting at the crank 80W power the motor will add 3*80=240W for a total of 320W.

• For the brisk pedalling rider inputting 150W the motor should add 3*150=450W for a total of 600W which would be pretty superhuman but motor power is capped at 250W so the motor adds “only” 250W making a total of 400W.

So in Turbo mode the motor is much less sensitive to rider input. It pretty much always chips in 250W regardless of how much power the rider is putting in. This is one of the factors that can make riding in Turbo mode feel less natural. Rather than the rider feeling his power has been amplified it feels more like a constant strong push in the back, largely regardless of rider input.

One compromise which we have used up to now is the use of the in between Sport mode which splits the difference between Tour and Turbo. The new eMTB mode seeks to improve on this.

eMTB Mode

After the update eMTB mode replaces the Sport mode in the old line-up of modes which now becomes: Off-Eco-Tour-eMTB-Turbo. eMTB mode can vary the support level between the 120% a rider normally gets in Tour-mode and the 300% of Turbo-mode. It doesn’t switch between modes but it calculates and appropriate level of support between 120% and 300% on the fly depending on speed, rider behavior and pedal torque. The idea being to maintain the natural progressive Pedelec feeling whilst pitching in power when it is really needed. This without the rider needing to continually switch modes making the the whole thing maintain a natural feeling… while becoming just that little more magic.

Bosch also claim that with “Direct Flow” support when pushing off in mode difficult circumstances, for example up a slope, will be significantly improved as power will be instantly available at push-off without causing traction issues by feeding in too much power at that instant, waiting with the power until the rider has actually started up the slope. We can see this working as it sounds a lot like the Tour-Sport-Turbo mode dance we have done many times but now done automatically, efficiently and allowing us to concentrate on riding.

Bosch’s hash-tag for these systems is #uphillflow. It sounds like a fair description to us.

Coming July 2017

 The update will be available from July 2017 on all Performance CX motors from 2016, 2017 and beyond. All that will be required is a software up date at your local Bosch Service Center