Help! 'Starter button' wanted for Bafang mid-drive (and Mahle hub)

Crankwinder

Finding my (electric) wheels
May 25, 2023
12
1
I've recently electrified my wife's bike. I did my research and fitted a Bafang 250W mid-drive motor with 40T Lekkie 'bling-ring', whilst upgrading the rear shifting to 11-speed in order to get a low-as-easily-possible bottom gear via an 11-51T cassette. It's great, she can now ride up anything Derbyshire County Council cares to spread tarmac on and a lot that they don't - although we haven't yet tried it on Bamford Clough!

That's provided Helen can start somewhere flat-ish and doesn't have to stop for anything partway up. For good reasons I won't go into here, although she's a most experienced rider, starting off has never been easy and lately she's become unable to launch into the saddle until the bike is well under way. I hoped that E-assist would help with that too, but it hasn't. If anything, the extra weight has made starting more difficult - especially uphill.

Here's what happens: the right pedal goes down, the bike goes forward and does receive a nice little electric boost - that immediately dies away, because the pedals are not moving any more, so the bike slows down again before she feels sufficiently confident to commit. A higher gear works better, that and max assist gives enough of a push, enough speed that lasts just long enough on a slight upward slope, for Helen to feel that the bike is moving well enough to risk putting ALL of her weight on that downward pedal, sit on the saddle and find the left pedal with her other foot, then PEDAL! That's improving her starting confidence, but I can't see it ever being enough for the really steep hills, where the the bike stops very promptly once the right pedal is down and there's no more power. By the way, I have set the controller so that power kicks in after only one pole has passed the cadence sensor.

I thought that walk-assist ought to do the trick. If the bike would just go at walking pace, that should nevertheless be enough for Helen to commit and pedal on. But sadly, the Bafang mid-drive's walk assist mode seems to be limited by chainwheel cadence, rather than actual road speed, to a slow enough motor rpm to ensure that 3.7mph is not exceeded even in the highest gear that any receiving bike is ever likely to be equipped with! As Helen's bike is geared quite low, it goes even slower than that, even in top - strolling rather than walking pace. And the torque also seems to be limited in walk-assist mode, to just enough to move the bike, not both bike and rider and certainly not in top gear up a steep hill!

Can anyone suggest some way of getting into the deep settings of the controller, so as to make walk-assist more speedy and powerful? The display is model 500C.

I realise that the simple solution would be to fit the throttle that came in the kit. But Helen doesn't want anything illegal on her bike. And all she really needs is a starter button delivering full power and any legal speed for say three seconds, then cut. I expect you'd get that result by briefly connecting two of the three wires in the redundant-in-UK throttle cable dangling temptingly from the handlebars. But can one buy such thing as a Bafang starter button ready made? I realise that would be illegal too, but a stronger argument could be made for such a gadget, especially if it were designed so it couldn't be pressed continuously and timed out for say 30 seconds, before resetting.

I know another cyclist who's lately got an E-bike - that gets him up the hills but doesn't get him started. He's a very strong rider on the flat (we all tuck in behind when Dave gets rolling!), but that's all thanks to his left leg. His right leg has nerve-damage and isn't sufficiently strong or controllable to push the pedal down for a hill start, or to stand on while his left leg does the job. So he points his bike down the hill then does a U-turn. Not easy on any road, very tricky on a steep hill and possible only if the road is wide enough, which most steep hills aren't! A starter button is exactly what Dave needs too and if E-bikes are supposed to help less able cyclists, I think he should be allowed to have one. So does anyone know if it's possible to add such a feature to a Ribble E-road bike equipped with the Mahle hub?
 

chris_n

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Apr 29, 2016
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I actually use a dropper seat post for a similar reason. Where I ride is off road in the Alps. Often I will have to stop on a steep uphill section to get past a gate etc. If I tried to start with seat at normal height even at fairly low power I would get wheel spin. With the dropper post fitted I can just drop the seat as I stop then pull away in a seated position. As soon as I am moving I take my weight off the seat and press the lever to return the seat to it's original height.
 
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saneagle

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Oct 10, 2010
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I've recently electrified my wife's bike. I did my research and fitted a Bafang 250W mid-drive motor with 40T Lekkie 'bling-ring', whilst upgrading the rear shifting to 11-speed in order to get a low-as-easily-possible bottom gear via an 11-51T cassette. It's great, she can now ride up anything Derbyshire County Council cares to spread tarmac on and a lot that they don't - although we haven't yet tried it on Bamford Clough!

That's provided Helen can start somewhere flat-ish and doesn't have to stop for anything partway up. For good reasons I won't go into here, although she's a most experienced rider, starting off has never been easy and lately she's become unable to launch into the saddle until the bike is well under way. I hoped that E-assist would help with that too, but it hasn't. If anything, the extra weight has made starting more difficult - especially uphill.

Here's what happens: the right pedal goes down, the bike goes forward and does receive a nice little electric boost - that immediately dies away, because the pedals are not moving any more, so the bike slows down again before she feels sufficiently confident to commit. A higher gear works better, that and max assist gives enough of a push, enough speed that lasts just long enough on a slight upward slope, for Helen to feel that the bike is moving well enough to risk putting ALL of her weight on that downward pedal, sit on the saddle and find the left pedal with her other foot, then PEDAL! That's improving her starting confidence, but I can't see it ever being enough for the really steep hills, where the the bike stops very promptly once the right pedal is down and there's no more power. By the way, I have set the controller so that power kicks in after only one pole has passed the cadence sensor.

I thought that walk-assist ought to do the trick. If the bike would just go at walking pace, that should nevertheless be enough for Helen to commit and pedal on. But sadly, the Bafang mid-drive's walk assist mode seems to be limited by chainwheel cadence, rather than actual road speed, to a slow enough motor rpm to ensure that 3.7mph is not exceeded even in the highest gear that any receiving bike is ever likely to be equipped with! As Helen's bike is geared quite low, it goes even slower than that, even in top - strolling rather than walking pace. And the torque also seems to be limited in walk-assist mode, to just enough to move the bike, not both bike and rider and certainly not in top gear up a steep hill!

Can anyone suggest some way of getting into the deep settings of the controller, so as to make walk-assist more speedy and powerful? The display is model 500C.

I realise that the simple solution would be to fit the throttle that came in the kit. But Helen doesn't want anything illegal on her bike. And all she really needs is a starter button delivering full power and any legal speed for say three seconds, then cut. I expect you'd get that result by briefly connecting two of the three wires in the redundant-in-UK throttle cable dangling temptingly from the handlebars. But can one buy such thing as a Bafang starter button ready made? I realise that would be illegal too, but a stronger argument could be made for such a gadget, especially if it were designed so it couldn't be pressed continuously and timed out for say 30 seconds, before resetting.

I know another cyclist who's lately got an E-bike - that gets him up the hills but doesn't get him started. He's a very strong rider on the flat (we all tuck in behind when Dave gets rolling!), but that's all thanks to his left leg. His right leg has nerve-damage and isn't sufficiently strong or controllable to push the pedal down for a hill start, or to stand on while his left leg does the job. So he points his bike down the hill then does a U-turn. Not easy on any road, very tricky on a steep hill and possible only if the road is wide enough, which most steep hills aren't! A starter button is exactly what Dave needs too and if E-bikes are supposed to help less able cyclists, I think he should be allowed to have one. So does anyone know if it's possible to add such a feature to a Ribble E-road bike equipped with the Mahle hub?
You can fit a throttle. It's not illegal. People keep saying it's illegal, but it isn't. The rule is that power must stop when you stop pedalling if your speed is over 4 mph. That's exactly how the Bafang BBS** works. You just set the throttle to 4 mph and the pedal assist to 15.5 mph. In that case, the throttle will start you off and reach a maximum speed of 4mph unless you pedal. As soon as you pedal, the pedal assist speed limit takes precedence. You can control the speed and power with the throttle while pedalling. As soon as you stop pedalling the motor power will cut unless your speed is below 4mph. If you let go of the throttle while pedalling, whatever power and speed settings you have selected for pedal assist take over. All that is perfectly legal.

 
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guerney

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Sep 7, 2021
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I've recently electrified my wife's bike. I did my research and fitted a Bafang 250W mid-drive motor
Which one? There are several Bafang mid-drive owners here. Mine's a 36V 250W BBS01B.


A higher gear works better, that and max assist gives enough of a push, enough speed that lasts just long enough on a slight upward slope,
I have no difficulty starting pedal assist on steep hills, provided I'm on a low enough gear when I stop, or I end up having to cycle downhill a bit, or to the side, or I zigzag up if there's enough room. Setting "Keep Current" to 100% using the Speeed App and a Bafang programming cable helps, otherwise power drops off uselessly. Factory settings are absolutely awful, mine were.


53413
 
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guerney

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Sep 7, 2021
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Crankwinder

Finding my (electric) wheels
May 25, 2023
12
1
You can fit a throttle. It's not illegal. People keep saying it's illegal, but it isn't. The rule is that power must stop when you stop pedalling if your speed is over 4 mph. That's exactly how the Bafang BBS** works. You just set the throttle to 4 mph and the pedal assist to 15.5 mph. In that case, the throttle will start you off and reach a maximum speed of 4mph unless you pedal. As soon as you pedal, the pedal assist speed limit takes precedence. You can control the speed and power with the throttle while pedalling. As soon as you stop pedalling the motor power will cut unless your speed is below 4mph. If you let go of the throttle while pedalling, whatever power and speed settings you have selected for pedal assist take over. All that is perfectly legal.

Thanks for that information. I didn't imagine for one moment that it would be possible to limit the throttle to a different speed than pedalling, but I can see that if it's limited to 4mph, the throttle becomes legal as a walk-assist control. That'll be perfect - even better than my idea of a starter button!
 
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StuartsProjects

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May 9, 2021
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That'll be perfect - even better than my idea of a starter button!
Indeed, safer too, reduced risk of being squished, if you fall over, by cars flooring the throttle when the lights go green.

Standard KT controllers should support the throttle use up to 6kmph without peddling, but I cannot get it to work, the speed 'limit' varies with the assist setting.
 

Crankwinder

Finding my (electric) wheels
May 25, 2023
12
1
Which one? There are several Bafang mid-drive owners here. Mine's a 36V 250W BBS01B.
Same one. I didn't think there were any other 250W Bafang mid-drives currently available (but I guess there must once have been a BBS01A).
 

guerney

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Sep 7, 2021
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Same one. I didn't think there were any other 250W Bafang mid-drives currently available (but I guess there must once have been a BBS01A).
BBS01 kits are still available to buy on AliExpress.


Thanks for that information. I didn't imagine for one moment that it would be possible to limit the throttle to a different speed than pedalling, but I can see that if it's limited to 4mph, the throttle becomes legal as a walk-assist control. That'll be perfect - even better than my idea of a starter button!
If you manage to limit the throttle to 6km/h, please do let us know how - it isn't possible using the Speed app or Penoff's configuration tool on the BBS01B.
 
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guerney

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Sep 7, 2021
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Yes, but I seem to get the impression that some officers of the law may assume that throttles are plain illegal, but maybe I have that wrong.
I have zero confidence of the average cop's ability to discern a legal throttle from an illegal one. I've ordered a quick-fit throttle for my repair kit and emergency use (if one of my legs falls off, or something).
 
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saneagle

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Oct 10, 2010
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I have zero confidence of the average cop's ability to discern a legal throttle from an illegal one. I've ordered a quick-fit throttle for my repair kit and emergency use (if one of my legs falls off, or something).
It's not exactly difficult. Either the rider id pedalling or not!
 

guerney

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Sep 7, 2021
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It's not exactly difficult. Either the rider id pedalling or not!
Any time I see a cop, I make sure to pedal even if I'm going downhill!
 

Crankwinder

Finding my (electric) wheels
May 25, 2023
12
1
Standard KT controllers should support the throttle use up to 6kmph without peddling, but I cannot get it to work, the speed 'limit' varies with the assist setting.
By "standard KT controllers" do you mean the controller that is neatly integrated already with the Bafang mid-drive? I'm afraid I wouldn't be happy about extracting that and swapping it for some other, separate controller, although there is space provided in the battery receiver for one.

However, if the included controller does nevertheless allow the throttle (when limited to 6kmph) to provide full torque without pedalling up to a speed close to 6kmph when the maximum pedal assistence level is selected, that would do fine. Helen can easily tap the assistance level back down to where she wants it, once safely under way. From your experience, do you think that would work?
 

Crankwinder

Finding my (electric) wheels
May 25, 2023
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Apparently what I want is specifically allowed in Germany and called 'Start Assist'. I received this informative reply to my post on another forum:
Since 2013 Germany allows ebikes to have a 6km/h start assist (Anfahrhilfe), which is distinct from walk assist/push assist (Schiebehilfe).

This is the English version of the explanation of start assist from Kalkhoff's website:
https://www.kalkhoff-bikes.com/en_gb/le ... art-assist

I came across the following advert for a Bafang motor in Germany, with a throttle option and mention of start assist. If the Google automatic translation is accurate, it seems that the software cannot be altered to restrict the speed to 6km/h when using the throttle:
In Germany, the throttle lever is only permitted as a starting aid up to 6 km/h. It cannot be throttled to 6 km/h on the software side and is therefore not legally usable.
https://1-gd--systems-de.translate.goog ... _tr_pto=sc
Shucks. It seems like I'd be wasting my money on a Bafang programming lead and my time on trying to get it to do what I want. Unless someone on here has actually done this themselves and can tell us exactly how they did it!

One avenue may remain open to me. I could bite the bullet of removing or bypassing the Bafang motor's integral controller and fit an alternative controller in the space provided for such, in the carrier-fitted receiver of the (non Bafang) 36V/13Ah battery I chose for this build.

But: has anyone here actually done this? And did you succeed in getting a workable start-assist function out of it, in addition to normal and legal operation of the Bafang mid-drive?