• 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.

    UK Pedelec Law

    Worldwide Laws

    We advise members great caution. EMTB Forums accepts no liability for any content or advice given here. 


Derestricting bosch smart system

tatane

New Member
Jun 25, 2023
59
41
Southern France
I put together a H Bridge type circuit to reverse the current running through the coil, accounting for the positive to negative pole change of the magnet as it passes. Here's a quick demo of the coil output.

First attachment shows running in positive direction for one second, then off, then negative direction for one second, then off and repeat.

Second attachment shows this applied to the setup mode. Its interval and pulse width is for a 15kph constant speed. For half the pulse width the coil is positive, then for the second half the coil is negative, representing the passing magnet. The amplitude appears to be changing simply because phone sensor isn't fast enough to pick up the true readings at this rate.

Is this what you're thinking?

View attachment 120750 View attachment 120753
Comparing your curves to @Mervious ones you may want to reverse the polarities there as it seems curves start with negative before going positive when the magnet passes tho
 

megabobra

Active member
Jul 24, 2022
223
252
Australia
Comparing your curves to @Mervious ones you may want to reverse the polarities there as it seems curves start with negative before going positive when the magnet passes tho
That probably doesn't matter, as in practice that direction would change depending on the random orientation the rim magnet is installed in - spin it 180 and it'll reverse.
 

Patcho

New Member
Aug 28, 2023
7
2
Netherlands
I installed the volspeed today. After research, this or the speedfun seems to be the better option. I went for the volspeed because you can choose a speed of up to 45 km. I set this to 33 km but the motor does not stop above that, the support then becomes less. There is no on or off anymore. Feels so much better to ride it. I deleted the flow app. Idk if needed, i like to use the navigation on the screen. Prefer the speed more :)
 

GBikeBoy

New Member
Jul 4, 2023
8
4
New York
I installed the Speedbox on my 2023 Bosch smart system (on a Cube). I got four errors and four limp home modes (lots of slow cycling). So I then replaced it with the Volspeed - it's been terrific. No complaints thus far - very happy with it. Highly recommended. I also deleted the Flow App ..
 

Patcho

New Member
Aug 28, 2023
7
2
Netherlands
I installed the Speedbox on my 2023 Bosch smart system (on a Cube). I got four errors and four limp home modes (lots of slow cycling). So I then replaced it with the Volspeed - it's been terrific. No complaints thus far - very happy with it. Highly recommended. I also deleted the Flow App ..
Great, cube here 2
 

Patcho

New Member
Aug 28, 2023
7
2
Netherlands
I use the flow app. What do you mean with dynamic mode?
Setting of a “softer control behavior” possible (dynamic mode). This significantly reduces the otherwise very abrupt reduction in speed limits.

So i can set it to full speed 45 like yours. With volspeed i can set it to what ever i want. And when i turn on dynamic mode there is no off when i go to my max set speed.
So if u set it to 32 and when im going 33 there is still support but smooth getting less. Feels more like a normal bike behavior

Dynamikmode.jpg
 

Sander

Member
Dec 29, 2022
50
28
NL
Very interesting read on the patent. Sadly it'll be some time before I get to the 1000km mark, but yes I completely agree with as much testing as possible is needed . Frankly I'm not in an rush to build devices if there's a risk that they'll behave like this in the longer term. @Sander , I wonder if you might have the greatest number of km on the device now - please keep us informed?
Having said that, I'd say there's always going to be improvements made to the detection routines for these devices, to the point where someday it won't be possible outsmart it. Maybe it's just best to make the most of it while we still can!!



Yes agree. I wonder how sophisticated the measurement is though, because that patent refers to the profile or ramping up/down of the signal as well. With the electromagnet in place, even with exactly the right strength to mimic the magnetic field, the ramping up and down is going to look very different. Where the passing magnet on the wheel will create a nicely smooth sine wave, the coil will be very much a square-edged step wave.
1226 km so far with the bobra. I had in 2 runs that the motor turned off. That was in a big jump and heavy breaking so I guess maybe the battery contact? When I turned it on again it turned itself off. So I removed the battery and the problem was solved. Unfortunately I didn't had turned on the flow app, so I could not see the error code. But yeah it still runs smouth. Also the bobra which a made for a friend runs smoothly.
 

Sander

Member
Dec 29, 2022
50
28
NL
Hi Mervious,
First regarding the winding, 100 turns at 0.3mm giving 3.2ohm sounds exactly like mine. I've got a 6.6ohm resister in place to bring the total to ~11ohms. I think it's more the placement you need to perfect. Its not so much sensitive within 1mm, but looking at your photo, my coil is around 10mm higher than yours, see the snip attached.

I bend my coil so it straddles that circled lump in the motor case. Give that location a try?

Ps yes I noticed the same with the coil remaining powered on and put the same fix in, albeit for 2secs - but I never got around to uploading the updated code ;)

View attachment 119717
So I run your first original Megabobra code. But understand it's better to put in this code line "
const unsigned long MAX_MAGNET_DURATION = 2000; // Maximum allowed duration for the electromagnet in milliseconds" at the 3rd row? In between "#define ELECTROMAGNET_PIN 3" and "byte LastButtonState;" ?

Thanks Bobra!
 

megabobra

Active member
Jul 24, 2022
223
252
Australia
So I run your first original Megabobra code. But understand it's better to put in this code line "
const unsigned long MAX_MAGNET_DURATION = 2000; // Maximum allowed duration for the electromagnet in milliseconds" at the 3rd row? In between "#define ELECTROMAGNET_PIN 3" and "byte LastButtonState;" ?

Thanks Bobra!

There are a few other changes needed to implement the line above. Your best way would be to update to the latest version of the code from the tutorial, here. It uses the same pins as your original code, so you would just need to change the multiplier figure to suit your setup and then load it up on your Nano.

Let me know if you get stuck?
 

Sander

Member
Dec 29, 2022
50
28
NL
There are a few other changes needed to implement the line above. Your best way would be to update to the latest version of the code from the tutorial, here. It uses the same pins as your original code, so you would just need to change the multiplier figure to suit your setup and then load it up on your Nano.

Let me know if you get stuck?
I run multiplier 1.4, fast enough for me :cool:
 

Mervious

New Member
Jul 7, 2023
12
11
Finland
Have been some time since my last post, maybe I'll update now. Have been raining almost every day on July and August so haven't ridden too much. Now on September few better days so have been riding again.

There were still issues even with the new code, so most likely the issues are elsewhere else than code. Sometimes it worked perfectly and something it went full crazy, fluctuating the speed like 60 km/h then a second later 20 km/h and then second later again 45 km/h and so on. I still kept it as is and tried to use it since it sometimes worked. One time then when I was biking with my friends it went crazy again so I made it "stock" by removing the brake disc magnet and adding the rim magnet in place. At least then I could pedal 25 km/h again for the rest of the ride. And actually I kept it like that until this week because I was tired of these problems already.

When I updated the code back in July, it worked fine when testing without any kind of water tight cover, and then I was surpriced that when I sealed it waterproof in my 3D printed cover, display only showed 0 km/h. When I removed the cover, everything worked again without issues. Then I noticed that the cover is so tight that it pushes a resistor to the reset button when the arduino is in the cover 😅 Problem got solved. At least I though so.

Anyways at first ride, everything worked perfectly like mentioned before. But then the crazyness started to happen quite soon. When I made the bike "stock", I though that the issues might be still the 3D printed cover if it pushes the reset button every now and then from vibration or something like that. So this week I removed the printed cover totally and just used plastic bags to make it waterproof (didn't have big enough heat shrinks) to test it out. And again was a lot of fun to drive faster than 25 km/h but then the issues started to happen again. This time it can't be the reset button.

But it seems to work pretty much perfectly if it works fine at the start. Today when I started to ride the bike, it was crazy. Then I shut the bike (and arduino) down two times and started them again, and then it worked without issues. And for the rest of the day it worked without any issues, even when I did shut the bike down few times during the day.

Might be something to do with the arduino itself. Maybe a faulty unit, or I might have broken it somehow when soldering everything in place. Who knows. But if it works by just restarting the bike, I can live with that for now. I have used way too much time on this already, at least for this season which is about to end anyway. At least the summer season...
 

megabobra

Active member
Jul 24, 2022
223
252
Australia
Have been some time since my last post, maybe I'll update now. Have been raining almost every day on July and August so haven't ridden too much. Now on September few better days so have been riding again.

There were still issues even with the new code, so most likely the issues are elsewhere else than code. Sometimes it worked perfectly and something it went full crazy, fluctuating the speed like 60 km/h then a second later 20 km/h and then second later again 45 km/h and so on. I still kept it as is and tried to use it since it sometimes worked. One time then when I was biking with my friends it went crazy again so I made it "stock" by removing the brake disc magnet and adding the rim magnet in place. At least then I could pedal 25 km/h again for the rest of the ride. And actually I kept it like that until this week because I was tired of these problems already.

When I updated the code back in July, it worked fine when testing without any kind of water tight cover, and then I was surpriced that when I sealed it waterproof in my 3D printed cover, display only showed 0 km/h. When I removed the cover, everything worked again without issues. Then I noticed that the cover is so tight that it pushes a resistor to the reset button when the arduino is in the cover 😅 Problem got solved. At least I though so.

Anyways at first ride, everything worked perfectly like mentioned before. But then the crazyness started to happen quite soon. When I made the bike "stock", I though that the issues might be still the 3D printed cover if it pushes the reset button every now and then from vibration or something like that. So this week I removed the printed cover totally and just used plastic bags to make it waterproof (didn't have big enough heat shrinks) to test it out. And again was a lot of fun to drive faster than 25 km/h but then the issues started to happen again. This time it can't be the reset button.

But it seems to work pretty much perfectly if it works fine at the start. Today when I started to ride the bike, it was crazy. Then I shut the bike (and arduino) down two times and started them again, and then it worked without issues. And for the rest of the day it worked without any issues, even when I did shut the bike down few times during the day.

Might be something to do with the arduino itself. Maybe a faulty unit, or I might have broken it somehow when soldering everything in place. Who knows. But if it works by just restarting the bike, I can live with that for now. I have used way too much time on this already, at least for this season which is about to end anyway. At least the summer season...
Intermittent problems like that are certainly the worst to track down. Assuming it had been working OK and your electromagnet position hasn't changed, then it does sound like maybe it's an issue with the nano or a connection? I got access to my device a few days back when fiddling with the dropped post cable and was surprised at how much dust/sand it was covered in. I'm going to remove the shrink wrap and seal it up property with some paint on liquid electrical tape, then shrink it back up.

Of course though, if these issues were happening from day one, then instead I think try adjusting the electromagnet position slightly and see if it improves.
 

Mervious

New Member
Jul 7, 2023
12
11
Finland
Intermittent problems like that are certainly the worst to track down. Assuming it had been working OK and your electromagnet position hasn't changed, then it does sound like maybe it's an issue with the nano or a connection? I got access to my device a few days back when fiddling with the dropped post cable and was surprised at how much dust/sand it was covered in. I'm going to remove the shrink wrap and seal it up property with some paint on liquid electrical tape, then shrink it back up.

Of course though, if these issues were happening from day one, then instead I think try adjusting the electromagnet position slightly and see if it improves.
Yeah possible. Only removable connection I have is from the reed sensor. Everything else is soldered in place. Have to say that the reed sensor connection isn't the best, might have some issues there. But that wouldn't explain why it starts to work after a reboot or two (without moving).

If I would have had the heat shrinks, I probably would have sealed the ends with just hot glue. Easy to remove afterwards if needed, and easy to apply.
 

Dano78

Member
Dec 3, 2019
162
34
Uk
So I'm picking up a ibis oso gen 4 bosch smart system and would like to tune it what seems to be the best option , I have no idea about the app as I'm coming from a trek rail 2020 so an early version on the bosch system thanks
 

Egon

New Member
Aug 27, 2023
16
9
Cambridge
I found a UK bike mechanic willing to swap over to the US firmware, thus increasing the limit to 20mph. He asked not to share his info publicly. You may have luck with your LBS
 

Egon

New Member
Aug 27, 2023
16
9
Cambridge
I’m hoping to approach this problem incrementally.

First, 20mph firmware, then set rear tire to 27 in while keeping 29 in wheel for additional speed boost (maybe an Extra 2mph?)

Then, a Speedi. That way, I’m not messing with the motor computer in any way.
 

Fuzz

Member
Jun 2, 2020
56
34
Yarrahapinni, NSW, Australia
Hi All, I've got the rotor magnet version, and still frustratingly riding around at 25kmh max assist, who's had long term success with any of the plug and play chips? By the way, does Megabobra have anything available for sale? thanks crew
 

megabobra

Active member
Jul 24, 2022
223
252
Australia
Hi All, I've got the rotor magnet version, and still frustratingly riding around at 25kmh max assist, who's had long term success with any of the plug and play chips? By the way, does Megabobra have anything available for sale? thanks crew
Nothing at the moment Fuzz. You can pick up all the bits you need from Jaycar though!
 

EMTB Forums

Since 2018

The World's largest electric mountain bike community.

527K
Messages
26,111
Members
Join Our Community

Latest articles


Top