Setting a speed limit on bafang mid drive

[matthewslack]

I notice that both the tsdz/vlcd5 and the kt controller hub setup has the facility to fit six magnets on the wheel or in the hubs. I notice that with the single magnet setup , there is a delay/lag with the speedo showing the correct speed but to some extent this could be expected as I presume the software has to count the pulses and possibly they are possibly not coming in fast enough. So I am wondering is there some advantage with six magnets?

Six magnets, potentially six times faster to respond, so that should help if the algorithm is written to take advantage.

External speed sensors with only one spoke magnet can only measure speed once per wheel revolution, which is about 2.2 metres for a 700c wheel. So that potentially gives a rapidly accelerating powerful motor a whole wheel revolution's worth of time beyond the first reading of 25km/h, plus any delay impact of a smoothing algorithm, before a smoothed speed reading of more than 25km/h is detected.

The power control algorithm then has to reduce power to get the speed back to 25, and that response will also be smoothed and so not instant. Speed overshoot is not surprising.

 

[guerney]

Having pored over every detail (including videos and audio when available) of every seizure in the "More seizures" thread, I haven't read of any cop testing maximum pedal assist speed with the driven wheel off the ground. I don't believe it happens, does anyone have proof that it does?

 

[Grigoriy]

Are the police testing maximum speed like that? If this really worries you, reduce speed limit to below 15.5mph/25kph in small increments until you judge it to pass such a daft copper roadside maximum speed test?

The prospect of coppers doing such a stupid roadside test hasn't worried me enough to do a no-load speed limit test on my own bike, but I might try at some point out of interest. Who goes nowhere pedelecing on their driveway stationary with the rear wheel spinning in the air?

Yes the do exactly like that here in the UK no matter how stupid they look and how much police time they waste by that instead of doing something more useful. They check speed on the motor display. One is operating and another lifting up the back wheel. First they check the throttle if you have one so it's not powering the motor to more then 3.7 mph without pedaling. That's how my last bike was confiscated with heavy fine and 6 points on my driving licence. Then they check motor wattage and maximum speed by turning the pedals by hands.
The prospect of lowering maximum speed under 15mph is not the option because there is no point of having electric bike with all that extra weight when any other cyclists on the regular bike takes over you?
I heard that by using EggRider v2 you can set the motor in the way that it's only possible to turn on off road unrestricted mode on only by the app. And every time when you turn off the display it goes back to the road, restricted mode. Any info about that?

 

[saneagle]

Having pored over every detail (including videos and audio when available) of every seizure in the "More seizures" thread, I haven't read of any cop testing maximum pedal assist speed with the driven wheel off the ground. I don't believe it happens, does anyone have proof that it does?

I've seen them do it in a Youtube video posted here about a year ago. I said at the time that I could have got the guy off if I was there. That's the only way they can test. they look for a throttle, lift the wheel up and open the throttle to see what speed is shown on the LCD. If you have an LED display with no speed indication or pedal assist only, they're pretty well buggered, but none of the Deliveroo bikes are like that.

 

[guerney]

Yes the do exactly like that here in the UK no matter how stupid they look and how much police time they waste by that instead of doing something more useful. They check speed on the motor display. One is operating and another lifting up the back wheel. First they check the throttle if you have one so it's not powering the motor to more then 3.7 mph without pedaling. That's how my last bike was confiscated with heavy fine and 6 points on my driving licence. Then they check motor wattage and maximum speed by turning the pedals by hands.
The prospect of lowering maximum speed under 15mph is not the option because there is no point of having electric bike with all that extra weight when any other cyclists on the regular bike takes over you?
I heard that by using EggRider v2 you can set the motor in the way that it's only possible to turn on off road unrestricted mode on only by the app. And every time when you turn off the display it goes back to the road, restricted mode. Any info about that?

II haven't read of the police testing no-load max speed like that, and will continue to not accept they do this, until there's proof.

The prospect of lowering maximum speed under 15mph is not the option because there is no point of having electric bike with all that extra weight when any other cyclists on the regular bike takes over you?
I heard that by using EggRider v2 you can set the motor in the way that it's only possible to turn on off road unrestricted mode on only by the app. And every time when you turn off the display it goes back to the road, restricted mode. Any info about that?

Might not be too bad if the the overshoot isn't massive, and you end up with speed limit of about 13mph? Have you tried @saneagle's method in this post with your Bafang display?

https://www.pedelecs.co.uk/forum/threads/setting-a-speed-limit-on-bafang-mid-drive.48212/post-735484

I haven't tried that either.

 

[saneagle]

Yes the do exactly like that here in the UK no matter how stupid they look and how much police time they waste by that instead of doing something more useful. They check speed on the motor display. One is operating and another lifting up the back wheel. First they check the throttle if you have one so it's not powering the motor to more then 3.7 mph without pedaling. That's how my last bike was confiscated with heavy fine and 6 points on my driving licence. Then they check motor wattage and maximum speed by turning the pedals by hands.
The prospect of lowering maximum speed under 15mph is not the option because there is no point of having electric bike with all that extra weight when any other cyclists on the regular bike takes over you?
I heard that by using EggRider v2 you can set the motor in the way that it's only possible to turn on off road unrestricted mode on only by the app. And every time when you turn off the display it goes back to the road, restricted mode. Any info about that?

You can do that with any bike that has a KT controller and display. Some of the Bosch dongles can be switched on and off from the light switch. There are many other ways to get the same, but if you're seen going uphill at some impossible speed for a fat middle-aged guy, they're going to get you.

 

[guerney]

I've seen them do it in a Youtube video posted here about a year ago. I said at the time that I could have got the guy off if I was there. That's the only way they can test. they look for a throttle, lift the wheel up and open the throttle to see what speed is shown on the LCD. If you have an LED display with no speed indication or pedal assist only, they're pretty well buggered, but none of the Deliveroo bikes are like that.

I've seen the no-load throttle speed tests videos too, but not a no-load pedal assist maximum speed test.

 

[saneagle]

I've seen the no-load throttle speed tests videos too, but not a no-load pedal assist maximum speed test.

Sorry, I misunderstood. I've never seen one either.

 

[guerney]

Sorry, I misunderstood. I've never seen one either.

A potential fix could be sticking a few 2mm needles on the pedals? Unless cops have kevlar gloves.

 

[Sturmey]

Six magnets, potentially six times faster to respond, so that should help if the algorithm is written to take advantage.

External speed sensors with only one spoke magnet can only measure speed once per wheel revolution, which is about 2.2 metres for a 700c wheel. So that potentially gives a rapidly accelerating powerful motor a whole wheel revolution's worth of time beyond the first reading of 25km/h, plus any delay impact of a smoothing algorithm, before a smoothed speed reading of more than 25km/h is detected.

The power control algorithm then has to reduce power to get the speed back to 25, and that response will also be smoothed and so not instant. Speed overshoot is not surprising.

The hub motor setup also uses the motor itself to measure the speed as the motor speed signal has a fixed reduction ratio to the wheel and is much faster. (e.g. by 88 or 100 times.) I think this signal is used for the 25Km/hr cut off as I was getting a wrong cut off speed on a hub and I fixed it by changing the P1 setting from 100 to 88.
One difference between the mid drive and the hub motor is that the motor to wheel ratio is not fixed with a mid-drive due to the variable gearing so I guess it would be difficult to use the motor speed signal as a speed indication.

 

[guerney]

The hub motor setup also uses the motor itself to measure the speed as the motor speed signal has a fixed reduction ratio to the wheel and is much faster. (e.g. by 87 or 100 times.) I think this signal is used for the 25Km/hr cut off as I was getting a wrong cut off speed on a hub and I fixed it by changing the P1 setting from 100 to 87.
One difference between the mid drive and the hub motor is that the motor to wheel ratio is not fixed with a mid-drive due to the variable gearing so I guess it would be difficult to use the motor speed signal as a speed indication.

I'm not putting more magnets onto my rear wheel and custom programming a replacement controller for my BBS01B, I'd rather pay a £200 fine and have 6 points added to my licence. There's no evidence the police are testing no-load maximum pedal assist speed.

I notice that both the tsdz/vlcd5 and the kt controller hub setup has the facility to fit six magnets on the wheel or in the hubs. ( I am not familar with the Bafang) I notice that with the single magnet setup , there is a delay/lag with the speedo showing the correct speed but to some extent this could be expected as I presume the software has to count the pulses and they are possibly not coming in fast enough with a single magnet. So I am wondering is there some advantage with six magnets? Just a thought (or possibly idle speculation) on a wet day.

I'm wondering if speed measurement on my BBS01B would become more accurate if I added a magnet and changed "Speed signal" to 2:





However, says here it won't:

"Speed Meter Signal: 1

The only setting that works is 1, again default. Don’t change it to anything different."

Bafang Programming - Learn how to improve your Bafang mid-drive ebike - Edrivenet

Learn how to improve your Bafang mid-drive ebike. Reprogramming your Bafang mid-drive system can improve the usability and performance of your ebike a lot.

edrivenet.com

 

[guerney]

I'm not putting more magnets onto my rear wheel and custom programming a replacement controller for my BBS01B, I'd rather pay a £200 fine and have 6 points added to my licence. There's no evidence the police are testing no-load maximum pedal assist speed.




I'm wondering if speed measurement on my BBS01B would become more accurate if I added a magnet and changed "Speed signal" to 2:


View attachment 62533


However, says here it won't:

"Speed Meter Signal: 1

The only setting that works is 1, again default. Don’t change it to anything different."

Bafang Programming - Learn how to improve your Bafang mid-drive ebike - Edrivenet

Learn how to improve your Bafang mid-drive ebike. Reprogramming your Bafang mid-drive system can improve the usability and performance of your ebike a lot.

edrivenet.com

Or... change wheel size to 10", and use two magnets? Until there's proof cops are doing such a stupid roadside test, I'm not doing anything.

 

[Sturmey]

I'm not putting more magnets onto my rear wheel and custom programming a replacement controller for my BBS01B, I'd rather pay a £200 fine and have 6 points added to my licence. There's no evidence the police are testing no-load maximum pedal assist speed.
I'm wondering if speed measurement on my BBS01B would become more accurate if I added a magnet and changed "Speed signal" to 2:

I dont think its necessary. It would be a full time job trying to stop them from falling off. But the guy below tried it.

Bafang Mid Motor: Multiple Speed Magnets

Some Bafang BBSHD and BBS02 programming tutorials say Speed Meter Signals must be set to 1 or bad things happen. They are right. They are also totally wrong.

talesontwowheels.com

 

[guerney]

I dont think its necessary. It would be a full time job trying to stop them from falling off. But the guy below tried it.

Bafang Mid Motor: Multiple Speed Magnets

Some Bafang BBSHD and BBS02 programming tutorials say Speed Meter Signals must be set to 1 or bad things happen. They are right. They are also totally wrong.

talesontwowheels.com

Thanks for finding and posting that link @Sturmey. My magnet has never fallen off, Bafang could make tightening the magnet screw easier by not using a weird star with central spike socket. Those Cateye magnets are available on ebay, for anyone interested (or sufficiently alarmed into being interested by unproven reports of cops doing no-load speed limit tests of pedal assist) in having a go:

https://www.ebay.co.uk/itm/133572652872

 

[saneagle]

I'm not putting more magnets onto my rear wheel and custom programming a replacement controller for my BBS01B, I'd rather pay a £200 fine and have 6 points added to my licence. There's no evidence the police are testing no-load maximum pedal assist speed.




I'm wondering if speed measurement on my BBS01B would become more accurate if I added a magnet and changed "Speed signal" to 2:


View attachment 62533


However, says here it won't:

"Speed Meter Signal: 1

The only setting that works is 1, again default. Don’t change it to anything different."

Bafang Programming - Learn how to improve your Bafang mid-drive ebike - Edrivenet

Learn how to improve your Bafang mid-drive ebike. Reprogramming your Bafang mid-drive system can improve the usability and performance of your ebike a lot.

edrivenet.com

Why not a magnet on every spoke, then change it to 36?

 

[guerney]

Why not a magnet on every spoke, then change it to 36?

Because I don't know what the upper limit is, they'd cost over £192 which is slightly less than the fine, several might need repositioning every so often after particularly violent pothole bumps like the one magnet I have now, and there are only 28 spokes on my rear wheel - ordered three Cateye magnets out of catlike curiosity, have made a note for getting around to seeing how much difference four magnets make (also the no-load 6kph limited throttle), after I get around to trying the no-load pedal assist test with one magnet, for something to compare with.

 

[sjpt]

The prospect of lowering maximum speed under 15mph is not the option because there is no point of having electric bike with all that extra weight when any other cyclists on the regular bike takes over you?

There are many reasons to use an ebike, with speed fairly low on the list for most people. It's true that many of us ride an ebike faster than we ride a regular bike, BUT not as fast as we rode regular bikes when we were 40 years younger. Apart from delivery riders on clearly illegal ebikes I am much more often overtaken by regular bikes than by ebikes, even though I think there are slightly more ebikes than regular ones in active use around here.

 

[saneagle]

Because I don't know what the upper limit is, they'd cost over £192 which is slightly less than the fine, several might need repositioning every so often after particularly violent pothole bumps like the one magnet I have now, and there are only 28 spokes on my rear wheel - ordered three Cateye magnets out of catlike curiosity, have made a note for getting around to seeing how much difference four magnets make (also the no-load 6kph limited throttle), after I get around to trying the no-load pedal assist test with one magnet, for something to compare with.

You should have said: I bought a box of 100 spoke magnets from Aliexpress for about a tenner about 8 years ago, and I've only used two.

 

[guerney]

You should have said: I bought a box of 100 spoke magnets from Aliexpress for about a tenner about 8 years ago, and I've only used two.

I knew you'd suggest using cheaper strong magnets. Fixing magnets to spokes at the right distance and keeping them there is tricky, I'd have to make consistent mounts, or a disc for a larger number of magnets (if allowed by firmware).... I'll get around to seeing what difference four magnets make, I'd be more motivated if there was any proof the fuzz were doing no-load pedal assist max speed tests - all for nought if a relentless roid rageing will to nick drives streroided arms resulting in speed in excess of 200mph.

 

[saneagle]

I knew you'd suggest using cheaper strong magnets. Fixing magnets to spokes at the right distance and keeping them there is tricky, I'd have to make consistent mounts, or a disc for a larger number of magnets (if allowed by firmware).... I'll get around to seeing what difference four magnets make, I'd be more motivated if there was any proof the fuzz were doing no-load pedal assist max speed tests - all for nought if a relentless roid rageing will to nick drives streroided arms resulting in speed in excess of 200mph.

28 for £14.86 inc. shipping

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