MEGABOBRA: Bosch Smart System Derestriction for Rim Magnet - DIY Project with Support

[AlumiPro]

Littleleye, sorry I somehow missed yours was also for sale. If Patcho hasnt already purchased, Id definitely consider. What would be total cost with shipping to US? I tried to send you a PM but am unable (account too new perhaps?). Try to send me one if you are able and we can move from there.

I may sell mine(never installed). I’m in California….if your other purchase doesn’t work out let me know.

 

[dlowe]

@megabobra where's the best place for an Aussie to buy the LPP cable? Here Bosch Power Supply Cable For 3rd Party Application ? I think I've found most other parts online, just need to get the bosch cable. Thanks!

 

[megabobra]

@megabobra where's the best place for an Aussie to buy the LPP cable? Here Bosch Power Supply Cable For 3rd Party Application ? I think I've found most other parts online, just need to get the bosch cable. Thanks!

Give these guys in melbourne a try.

Just note though that while their picture shows the 140cm cable, they actually sent the 20cm version - might be worth checking before hand depending on what you need.

Otherwise, I ordered my first cable through a local Trek retailer.


edit: oops, didn't realise that was the same place you already linked! Yep, that's the one - just note my comment on length above.

 

[tatane]

Give these guys in melbourne a try.

Just note though that while their picture shows the 140cm cable, they actually sent the 20cm version - might be worth checking before hand depending on what you need.

Otherwise, I ordered my first cable through a local Trek retailer.


edit: oops, didn't realise that was the same place you already linked! Yep, that's the one - just note my comment on length above.

Quite glad they didn't send you 140cm version, not sure where I would have put all that extra length when installing my megabobra

 

[dlowe]

Sweet, ordered. Step 1 complete. Now to source the other parts.

 

[megabobra]

Hi guys,

Just a quick mention on something that might hopefully assist some who had issues with weird speed jumps, particularly @littleleye.

Given my setup was used for development, I have a couple of LEDs mounted externally on the motor case, one shows when the reed switch is triggered and one shows when the electromagnet fires. These flash together for the first few revolutions of the wheel and then the electromagnet LED begins slowing down as the multiplier is introduced.

Anyway, I noticed that my rotor magnet had moved outward on the disc rotor after a wash. Spinning the wheel slowly, I was able to see the reed switch was sometimes being triggered twice as the magnet passed, a definite double flash. This then produced a double firing of the electromagnet, and naturally a displayed speed which went from ~10kph to 35kph instantly.

I'd never given much thought to the magnet position in the past, but after some experimentation there were definite locations where this occurred and where it didn't.

I actually ended up replacing the rotor magnet with much smaller one, from 8x4mm to 8x1mm circle. Much less magnetism (to the extent I had to stick it to the rotor with some doublesided tape) BUT I wasn't able to reproduce the double pickup, regardless of location.

So if anyone notices weird speed behaviour, particularly after a long run of no issues, definitely check the magnet location.
For those first fitting the devices, and for @littleleye if it's not too late, perhaps try a smaller magnet, or just to test out the theory, try mouning the provided magnet on the other side of the rotor (hub side) maybe with a few squares of foam tape to add some distance between it and the reed sensor.

 

[E Bob]

Hi all.. Has anyone fitted one of these to a canyon strive on ? Or used it in harsh riding and weather conditions "live in south wales, Ride fast gnarly trails and bike parks"

 

[tatane]

Hi all.. Has anyone fitted one of these to a canyon strive on ? Or used it in harsh riding and weather conditions "live in south wales, Ride fast gnarly trails and bike parks"

Hi, fitted one on my Strive on, works quite fine, and spot for the magnet is pretty easy to find/fix (as in, doesn't require taking out the whole motor to find/fit) ... Haven't had a chance to take it out to really harsh riding or weather conditions since fitting it but there's a way to fit the device quite snuggly in the downtube aside from the battery so that water wouldn't get to it even in the worst weather so it feels pretty safe there until proven otherwise

 

[E Bob]

Hi, fitted one on my Strive on, works quite fine, and spot for the magnet is pretty easy to find/fix (as in, doesn't require taking out the whole motor to find/fit) ... Haven't had a chance to take it out to really harsh riding or weather conditions since fitting it but there's a way to fit the device quite snuggly in the downtube aside from the battery so that water wouldn't get to it even in the worst weather so it feels pretty safe there until proven otherwise

Great thanks, ill have a look at the install video, see if im confident enough to fit myself

 

[tatane]

Great thanks, ill have a look at the install video, see if im confident enough to fit myself

Fitting is really easy, most "complicated" part being removing the Bosch Connect module (GPS tracker) ... only made difficult by the cable being pretty hard to remove from the tracker that scared the shit out of me the first time as I was scared to tear that tiny cable ...
Sweet spot for the coil on these is right at the bottom of the frame where you have just enough room to actually slip the magnet (it's almost like they had it planned lmao), as highlighted in my attached pic

 

[E Bob]

Fitting is really easy, most "complicated" part being removing the Bosch Connect module (GPS tracker) ... only made difficult by the cable being pretty hard to remove from the tracker that scared the shit out of me the first time as I was scared to tear that tiny cable ...
Sweet spot for the coil on these is right at the bottom of the frame where you have just enough room to actually slip the magnet (it's almost like they had it planned lmao), as highlighted in my attached pic

View attachment 125838

Thanks, I'v just looked right through this thread for install vid, or pictures. does megabobra include a diagram with it, also noticed he's stopped making, selling them. is this still the case ?

 

[tatane]

I don't think he's planning on doing any more of these but plans and software are available in this thread. I've made one myself and would consider my soldering skills as pretty basic (haven't soldered anything since college basically), hardest part being likely creating your coil and keeping it sturdy enough (tried one from amz as initially suggested in the thread, but that's too large to fit on the strive on unfortunately, so you'll really have to make your own there). There's also a couple people reselling theirs, maybe there's still some around ?

 

[E Bob]

I don't think he's planning on doing any more of these but plans and software are available in this thread. I've made one myself and would consider my soldering skills as pretty basic (haven't soldered anything since college basically), hardest part being likely creating your coil and keeping it sturdy enough (tried one from amz as initially suggested in the thread, but that's too large to fit on the strive on unfortunately, so you'll really have to make your own there). There's also a couple people reselling theirs, maybe there's still some around ?

Ahh, thanks Again.. I'm not savvy enough to make one of these, ill post see if anyone selling one.

 

[E Bob]

Anyone selling there megabobra ?

 

[manu.w]

Hello, here are my findings of my own build on my Bosch performance cx gen4, with rim magnet.
I use this self wounded electromagnet , that I power up with the 12V lpp port using a mosfet and a 50% pwm, consuming 0.12 amps .
My first test seemed to work but the readings on my phone were not stable…
After upgrading the flow app to the latest version 1.15.10, everything worked flawlessly
The arduino program is very basic , it only sends 1 magnet pulse 1 for 2 reed switch pulses.

 

[maxherbz]

Anyone still selling their device? I am interested in one too

 

[manu.w]

Hi guys,

Just a quick mention on something that might hopefully assist some who had issues with weird speed jumps, particularly @littleleye.

Given my setup was used for development, I have a couple of LEDs mounted externally on the motor case, one shows when the reed switch is triggered and one shows when the electromagnet fires. These flash together for the first few revolutions of the wheel and then the electromagnet LED begins slowing down as the multiplier is introduced.

Anyway, I noticed that my rotor magnet had moved outward on the disc rotor after a wash. Spinning the wheel slowly, I was able to see the reed switch was sometimes being triggered twice as the magnet passed, a definite double flash. This then produced a double firing of the electromagnet, and naturally a displayed speed which went from ~10kph to 35kph instantly.

I'd never given much thought to the magnet position in the past, but after some experimentation there were definite locations where this occurred and where it didn't.

I actually ended up replacing the rotor magnet with much smaller one, from 8x4mm to 8x1mm circle. Much less magnetism (to the extent I had to stick it to the rotor with some doublesided tape) BUT I wasn't able to reproduce the double pickup, regardless of location.

So if anyone notices weird speed behaviour, particularly after a long run of no issues, definitely check the magnet location.
For those first fitting the devices, and for @littleleye if it's not too late, perhaps try a smaller magnet, or just to test out the theory, try mouning the provided magnet on the other side of the rotor (hub side) maybe with a few squares of foam tape to add some distance between it and the reed sensor.

Best way to position the reedswitch and permanent magnet.
All what follows is that the permanent magnet is facing the reedswitch N or S! (The opposite as the attached picture shows)
The magnet should pass perpendicular to the reedswitch at either extremes !
If you pass a magnet along a reedswitch it will “fire” two times at the extremes.

 

[manu.w]

Just discovered that the powerful rim magnet it’s N-S is not perpendicular to the rim but parallel!!
So ideally we should place / orient the electromagnet the same way!?

 

[megabobra]

Do you mean like this?

Where the poles are at either side/end in this diagram when mounted on the rim?

 

[manu.w]

I will try to wind a new electromagnet because at high wheel revs, the Bosch sensor misses electromagnet pulses…

 

[manu.w]

Do you mean like this?

View attachment 126117


Where the poles are at either side/end in this diagram when mounted on the rim?

 

[manu.w]

Feedback:
By repositioning the electromagnet, and lengthen the magnetic pulse creation by the program (I was having irregular readings at high revs) i have really stable speeds in the flow riding app.
Ps: question, I still am hesitating to upgrade the bike Bosh firmware, is it ok to get the latest firmware?
Thanks

 

[megabobra]

Feedback:
By repositioning the electromagnet, and lengthen the magnetic pulse creation by the program (I was having irregular readings at high revs) i have really stable speeds in the flow riding app.
Ps: question, I still am hesitating to upgrade the bike Bosh firmware, is it ok to get the latest firmware?
Thanks

View attachment 126259

That looks excellent!
I'm running the latest motor firmware but haven't updated the app in a few weeks as I'm worried they'll correct the 'bug' that allows running the Ride screen without location on.

 

[AlumiPro]

Has anyone successfully put this on the new CX Race motor with no issues?
I got the LPP outlet turned on.
Found where the Bosch internal sensor is picking up the Megabobra magnet signal at a constant 14.2-14.3 MPH with the setup jumper wire connected. I get a nice smooth speed reading with the reed wire installed and spoke magnet for approx 5-10 seconds of pedaling the bike while being supported in a stand. Once I let up pushing the pedals by hand, I instantly get Code 523003 on the screen! I’ve moved the Megabobra magnet a little at a time and the code will still come up every time!
What is code 523003??….Fault with the internal magnet sensor reading??
I also got 523001 code at one point.

 

[manu.w]

Has anyone successfully put this on the new CX Race motor with no issues?
I got the LPP outlet turned on. Found where the Bosch internal sensor is picking up the Megabobra magnet signal at a constant 14.2-14.3 MPH with the setup jumper wire connected. I get a nice smooth speed reading with the reed wire installed and spoke magnet for approx 5seconds of pedaling the bike in a stand in tour mode, until I let off pushing the pedals. Instantly Code 523003 comes up on the screen! I’ve moved the Megabobra magnet a little at a time and the code will still come up every time!
What is code 523003?? Fault with the internal magnet sensor reading??
I also got 523001 code at one point.

Hagrrr, sad …

Error 523003
Speed sensor is not working correctly.
The speed may therefore not be correctly displayed to you. The output of the drive unit is likewise limited.

Error 523001
Speed sensor is not working correctly.
A reduced drive unit power may therefore be available to you. The speed is likewise incorrectly displayed.

 

[AlumiPro]

Hagrrr, sad …

Error 523003
Speed sensor is not working correctly.
The speed may therefore not be correctly displayed to you. The output of the drive unit is likewise limited.

Error 523001
Speed sensor is not working correctly.
A reduced drive unit power may therefore be available to you. The speed is likewise incorrectly displayed.

Thanks for the reply……and crap! So this will not work?
Or should I move the Megabobra made magnet around to see if it needs to be placed better.
Or could it be that the Megabobra made magnet isn’t strong enough or it’s too strong of a pulse?

 

[megabobra]

Thanks for the reply……and crap! So this will not work?
Or should I move the Megabobra made magnet around to see if it needs to be placed better.
Or could it be that the Megabobra made magnet isn’t strong enough or it’s too strong of a pulse?

Since you're getting a smooth speed with the setup mode plug connected, the coil positioning should be fine. Just confirming you've removed the original magnet from the valve stem right?
Try this:
Plug in your setup mode jump and let it sit for a min to ensure there's no speed fluctuation, watching the speed on Kiox or in the eplus app. Then with the system still powered, remove the setup jumper - speed will immediately drop to zero. Then Give the wheel a hard spin by hand (without using the pedals) and monitor the speed. It should drop quickly as the multiplier kicks in. You should be able to maintain a nice smooth speed after 10 revolutions (5 rev of 1:1 magnet firing, 5rev of incremental multplier addition) if you keep spinning it.

Keep spinning by hand for a minute or so and just watch the speed. How is it?

 

[AlumiPro]

Since you're getting a smooth speed with the setup mode plug connected, the coil positioning should be fine. Just confirming you've removed the original magnet from the valve stem right?
Try this:
Plug in your setup mode jump and let it sit for a min to ensure there's no speed fluctuation, watching the speed on Kiox or in the eplus app. Then with the system still powered, remove the setup jumper - speed will immediately drop to zero. Then Give the wheel a hard spin by hand (without using the pedals) and monitor the speed. It should drop quickly as the multiplier kicks in. You should be able to maintain a nice smooth speed after 10 revolutions (5 rev of 1:1 magnet firing, 5rev of incremental multplier addition) if you keep spinning it.

Keep spinning by hand for a minute or so and just watch the speed. How is it?

The Rim magnet has been removed since I started the instal.
I moved the Megabobra made magnet a bit higher up on the motor, which has made an improvement with not triggering an error code right away. The speed fluctuates from 14.3-14.4 with the set-up jumper wire in place (watched it for 1min) and the speed drops rapidly to zero when the jumper is unplugged. There is absolutely no room for a store bought electro magnet with my frame, it’s a very tight space which actually keeps the Megabobra one in place nicely. You definitely have to be patient; having to remove and reinstall the motor over and over and over trying to find the magnet sweet spot! (The set-up jumper wire definitely helps and is a must have, but doesn’t get it perfect for the picky Bosch sensor!)
I’ve now cycled through all the assist modes while peddling it by hand at a lot of different speeds and letting it coast to a stop, and doing sporadic speed changes to see if it would trigger an error code. I’m now only getting the error code after peddling it by hand really fast in an assisted mode (emtb or Race). Keep in mind this is all being done in a bike stand, I have yet to ride it……I’m now wondering if this is why the error code is coming up now at the higher sporadic speeds, being that the bike is held off the ground. I need to get it all put back together and take it for a ride. I figure I’ll always keep the Bosch rim magnet in my ridding pack so if I have troubles on the trail I can at least easily reinstall it and remove the spoke magnet disabling the Megabobra to finish my ride.
I also noticed when the wheel is coasting/loosing speed, the speed smoothly drops to approx 3-2mph then jumps up to 5-6mph, then smoothly slows to zero as the wheel comes to a stop. This speed flutter happens every time I let it coast to a stop, but does NOT trigger an error code. Is this Normal?
Does anyone know the torque spec for the six T40 motor bolts on a carbon frame?

 

[megabobra]

The Rim magnet has been removed since I started the instal.
I moved the Megabobra made magnet a bit higher up on the motor, which has made an improvement with not triggering an error code right away. The speed fluctuates from 14.3-14.4 with the set-up jumper wire in place (watched it for 1min) and the speed drops rapidly to zero when the jumper is unplugged. There is absolutely no room for a store bought electro magnet with my frame, it’s a very tight space which actually keeps the Megabobra one in place nicely. You definitely have to be patient; having to remove and reinstall the motor over and over and over trying to find the magnet sweet spot! (The set-up jumper wire definitely helps and is a must have, but doesn’t get it perfect for the picky Bosch sensor!)
I’ve now cycled through all the assist modes while peddling it by hand at a lot of different speeds and letting it coast to a stop, and doing sporadic speed changes to see if it would trigger an error code. I’m now only getting the error code after peddling it by hand really fast in an assisted mode (emtb or Race). Keep in mind this is all being done in a bike stand, I have yet to ride it……I’m now wondering if this is why the error code is coming up now at the higher sporadic speeds, being that the bike is held off the ground. I need to get it all put back together and take it for a ride. I figure I’ll always keep the Bosch rim magnet in my ridding pack so if I have troubles on the trail I can at least easily reinstall it and remove the spoke magnet disabling the Megabobra to finish my ride.
I also noticed when the wheel is coasting/loosing speed, the speed smoothly drops to approx 3-2mph then jumps up to 5-6mph, then smoothly slows to zero as the wheel comes to a stop. This speed flutter happens every time I let it coast to a stop, but does NOT trigger an error code. Is this Normal?
Does anyone know the torque spec for the six T40 motor bolts on a carbon frame?

Ok that's sounding good. Get it out for a real pedal and see how you go. Yes I've managed to get an error on my system even with the original rim magnet installed when pedaling in the stand - that's why I suggested spinning the wheel by hand rather than pedaling I don't think it likes running the motor power with so little torque being received from the torque sensor.

PS the smooth speed drop then bump back up is normal. The multiplier is set to 1 at low speeds, before being gradually reintroduced as you speed up again. So as you slowly reduce your speed to that 2-3mph threshold, you'll see it move back up again a few mph as the multiplier drops from your 1.6 to 1. This was to avoid cases where the multiplier reduces the interval sufficiently that at slow speeds the motor would see 0mph despite actually still moving along slowly.

 

[AlumiPro]

Thanks for the reply and info. That makes complete sense now, that the shown speed jumps back up before hitting zero. Sounding like I’ve got it set up right, looking forward to my first ride with it.(beginning of next week) I’ll keep you posted.
I’m guessing it’s fine to leave the Megabobra made magnet coil wire exposed? (I’m not a mud ridder.) I used 3M VHB double sided tape to secure it to the motor.