• Warning!!

    Riding a tuned or deristricted EMTB is not a trivial offence and can have serious legal consequences. Also, many manufacturers can detect the use of a tuning device or deristricting method and may decline a repair under warranty if it was modified from the intended original specification. Deristricting EMTB's can also add increased loads for motors and batteries. Riding above the local law limit may reclassify the bike as a low-powered bike, requiring insurance, registration and a number plate.

    Be aware of your local country laws. Many laws prohibit use of modified EMTB's. It is your responsibility to check local laws. Ignoring it, has potential implications to trail access, and risk of prosecution in the event of an accident.

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Derestricting bosch smart system

E

Embt

New Member
Aug 1, 2024
59
15
Dundee
Onetime said:
You told the other guy to, “Press -+-+ and ride it will be set to 18mph”. That sounds like a start up procedure to me. The speedfun is literally plug it in and ride. You don’t have to press anything and you don’t need a display. But to each his own.
Click to expand...
Well thats to activate it and press again to deactivate it.
Only negative false mileage and reading.

The startup process u have to wait 10 seconds on other hacks like the speedbox and wait upto 10 mins to for the shutdown no1 got time for that.
I could change the buttons to 1 button activate and de activate and I can set the max speed on the volspeed.
the Speedfun I would not enjoy doing 28mph.

And the activation and deactivation is instant incase the %0.001 chance I need to deactivate it with police
 
T

Thuppu

New Member
Jul 9, 2024
5
3
Finland
megabobra said:
Apologies for the repost of some of this, but this single post can be a single point of reference for the rim magnet derestrict.

My build is based on an Ardunio microcontroller, reed switch and electromagnet. I removed the bike's rim magnet and instead placed a traditional magnet on the disc rotor. The Arduino then uses the reed switch to sense the true RPM of the wheel, delays the time between magnet passes by a fixed multiplier and then activates the electromagnet at the new interval accordingly. The electromagnet is positioned up against the motor case.

With ~100 lines of code, everything is working great. I've got the multiplier set to 1.4 (eg where true speed is 20kph, motor will be shown 20/1.4= 14.3kph), giving a new max assisted speed of 35kph. The multiplier could be set to anything, say 2 would give assist to 50kph.

The beauty of this setup is the simplicity: no interruption of sensors from the motor, reducing chance of detection. So long as you don't go crazy with the multiplier, it'd be very difficult for the motor to detect this manipulation, as there are so many real-world variables which will mask it; rider weight, gear ratio, terrain etc. Some things may give it away though. For example, if you use a large multiplier, you may reach a point where for a given cadence it's just not physically possible to be traveling so slowly. Also if you use location tracking through the Eplus app, it may compare wheel speed with GPS speed and flag a discrepancy.

Some FAQ:

  • YES it will disrupt your total trip distance and odometer, but it's a simple multiplication to get the true figures. ie reported trip distance * chosen multiplier = true trip distance.
  • YES it should work on setups without the rim sensor. Instead of positioning the elctromagnet against the motor case, position it against the speed sensor.
  • Total power usage when the magnet is firing is ~2.4watts, and negligable when it's not firing (ie when the bike is stationary). Magnet is firing only around 8% of the time.


Here's a quick tutorial so you can build your own derestrictor for the smart system with rim magnet.

Components:
Of course there's plenty of equivalent components you can substitute here, so go with what's cheap/easy to get locally.


Wiring Schematic:

Reed switch: D8 and Ground
Transistor: Base > D3, emitter > electromagnet, collector > Ground
Electromagnet: 5v and transistor's collector leg
Voltage regulator: 5v and Ground

View attachment 105957

The Arduino nano has a built in regulator, so you can also wire the ~13v from the Bosch low power port direct to the Vin and Ground pins in order to omit the voltage regulator above. I had a spare regulator so figured I'd use it to monitor temperatures.

Note that you'll need your Bosch dealer to enable to the low power port before it will be powered.

I was also able to build my own electromagnet with some enameled copper wire. You need a coil resistance of ~15ohms. I used 100 turns around some pvc pipe ~ 25mm in diameter and a 0.5watt 10ohm resistor.

View attachment 105975

These work just as well as the commercial electromagnet and offer better flexibility of placement. If i was starting from scratch, it'd use this rather than the off the shelf product.


Programming

Load the attached code to the Arduino Nano with Arduino IDE. You can download it here.

You can update the Multiplier variable in the code (line 26) to alter the maximum assistance speed. I've got mine set to 1.4. This slows the actual wheel rpm by a factor of 1.4, moving the maximum assistance speed from 25kph to 35kph.


Installation

Snap the magnet on to the rear disc rotor. Mount the magnetic switch on the swing arm so that it's close to the rotating magnet.
The placement of the electromagnet is a bit tricky as the motor measures the strength of the magnet field, not just if a field exists. I found it best to mount the magnet facing AWAY from the motor (ie magnetic face towards the rear of the bike). Refer to the pics attached for my placement location. I'm using some foam to wedge it in place.

Once wired, the Arduino Nano and all wiring gets pushed into the frame.



Good luck and let me know if there are any questions. View attachment 105963 View attachment 105964 View attachment 105965 View attachment 105976 View attachment 105977
Click to expand...
Hello. This seems like a very nice and simpple solution for the rim magnet setup? Have it been reliable without errors >1000km? Anyone tested it this much?

I was thinking that could it be adjusted in the settings that the derestricting multiplier kicks in at higher speed say like 23kmh(14mph)? That way most of the riding would act as normal and could lower the risk for errors.
 
M

megabobra

Active member
Jul 24, 2022
254
266
Australia
Thuppu said:
Hello. This seems like a very nice and simpple solution for the rim magnet setup? Have it been reliable without errors >1000km? Anyone tested it this much?

I was thinking that could it be adjusted in the settings that the derestricting multiplier kicks in at higher speed say like 23kmh(14mph)? That way most of the riding would act as normal and could lower the risk for errors.
Click to expand...
Hi Thuppu,

Check out my post here: MEGABOBRA: Bosch Smart System Derestriction for Rim Magnet - DIY Project with Support

I've got lots of Km's now, along with OLED display various options, but you your success will depend on your motor firmware version.

PS my code progressively introduces the multiplier from ~10kph onwards (and gradually decreases when slowing down) so that the reported speed isn't too low when traveling up a steep climb for example. Though once you get up above 15kph or so there's no need to restrict the multiplier.
 
SEBA

SEBA

Active member
Sep 11, 2019
346
129
French Provence High Alps
Egon said:
Found a solution for 25mph (in UK) without mod chips that will void warranty.

I had my bike shop set my wheel size to 26 in. (in the settings). That gave me an extra 1.5 mph. I then bought a used SPEEDi and installed it. Now I cruise at around 25mph with full assist.

Haven't gotten the firmware flashed to US spec...yet. That will bring me to 30 mph undetectable.
Click to expand...
lbs can do 26' it without asking bosch ?
 
T

Thuppu

New Member
Jul 9, 2024
5
3
Finland
megabobra said:
Hi Thuppu,

Check out my post here: MEGABOBRA: Bosch Smart System Derestriction for Rim Magnet - DIY Project with Support

I've got lots of Km's now, along with OLED display various options, but you your success will depend on your motor firmware version.

PS my code progressively introduces the multiplier from ~10kph onwards (and gradually decreases when slowing down) so that the reported speed isn't too low when traveling up a steep climb for example. Though once you get up above 15kph or so there's no need to restrict the multiplier.
Click to expand...
Ok, so this is the case atm. Should have done my homework better before purchasing a new bike.. fimware version seems to be 9.13. Thanks for the info. Have missed the other thread.
 
E

Embt

New Member
Aug 1, 2024
59
15
Dundee
I've done 150 miles no errors so far.
18.5, mph is the sweet spot for me for leisure. I constantly slowing down speeding up with pedestrians and cars so maybe not detect it.

Love the bike now.

Mybrainhurts take sleep its not a blog lol
 

robbydobs

robbydobs

Member
Jan 31, 2021
99
86
Sussex, UK
CATA20034 said:
Hello,

I'm a hardware developer, and also a new owner of this crappy smart system. I wanted to see exact what kind of sensor is using inside the motor, for the RIM magnet, took the motor out and opened it. Unfortunately I cannot find any datasheets of it. It seems a multi axis hall sensor with SPI, at least based on the pin count and signal routing. Now if we are dealing with a 3 axis hall sensor I don't think it will work the electromagnet. I attached a picture with it. Maybe next week i will pull out the signals trough a cable and check what signals are provided to the microcontroller. Is still hope there is a PWM line from the sensor that can be ower-written.

View attachment 143776
Click to expand...
I wonder if this is similar to

A1334 High Resolution Programmable Angle Sensor with SPI Interface

Allegro's A1334 is a 360° contactless, high resolution magnetic angle position sensor.
www.digikey.co.uk www.digikey.co.uk
It seems to have a very high sample rate. Could that be why the solution by @megabobra does not work? I have not checked the code, but how frequent is the shape of the magnet field altered? It could be that the sensor used for testing can't sample as quickly as this one so it's not possible to see the differences?
 
AlumiPro

AlumiPro

Active member
May 1, 2023
199
148
California
SEBA said:
there 's no solution to deristrict magnet rim

stop doing sh1t with all your f**king hw omg
Click to expand...
The only way to deal with the rim magnet is to convert the system to a spoke magnet setup, using Bosch hardware. Then throw the rim magnet in the trash and forget it ever existed!
IMG_8039.jpeg
 
Last edited:
S

Sir_Szendi

New Member
Apr 10, 2024
11
1
Poland
In my case, Bosch and the bicycle manufacturer (Focus) do not want to agree. I found another solution. Software change for the American market. Then the speed is up to 32 kilometers per hour. Unfortunately, I updated the softwere and I have to wait until the "magician" I found has the new software.
 

E

Embt

New Member
Aug 1, 2024
59
15
Dundee
There is a new update for the smart system the bike and flow app today.

I decided to update it with the chip installed but not activated and works so far.
 


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