Pedal assist won't re-engage

Joined
Jul 2, 2020
Messages
12
Well, the problem I have is that the pedal assist won't re-engade.

Let's say that I ride the bike and approach a curb, I stop to pedal for a few seconds and after the curb I start to pedal again.
Going into the curb the bike works and the battery is fully charged, coming out of the curb all lights are on but the motor doesn't engage until after I use the control panel to do an off/off cycle.

The bike is a cheap 7-gear model of the Swedish bland Yosemite and the motor I believe is Baofeng.

Since the bike is out of warranty I need to troubleshoot it myself but I am at a loss of where to start.

Any useful hints anyone?
 
What specifically do you mean by "approach a curb" and "after the curb"?

Do you mean riding up onto a sidewalk and then coming off of it, which would jolt the system mechanically?

Or something else? (if so, what?)
 
Sorry, I thought I was clear.
I mistook the word curb for turn (kurva in Swedish).

Start to ride the bike and pedal and all good, stop to pedal for a few seconds and just let the bike roll by momentum and the motor doesn't start again when I start to pedal again.
 
No problem; you do much better in English than many native speakers I know, and better than I can do in any other language than English. ;)

Has this problem always existed, or did it suddenly start; if the latter, what specifically happened between the time it worked and the time it didn't? Sometimes knowing that will help narrow down possible causes.

Does it happen only at one specific location on the streets, or at any point where you stop pedalling for a few seconds? Is it intermittent, or every time?

Does it happen if you stop pedalling only for say, one crank rotation time? (meaning, you just pause in pedalling for a second or less).

Does pedalling backwards cause it as well? (a systems could detect reverse pedalling and go into a different (braking, etc) mode and if that mode doesn't work as the controller expects it could "lock up" and require a reboot/reset).

Does it matter what level your battery is at, or does this problem happen at full, empty, and everywhere between? (if the former, it might be battery-voltage related, even if not caused by the battery).

Does it happen the same if you flip the bike upside down and move the pedals with your hands, with the wheels in the air?



Most of the time things like this are caused by system timeouts, but those are usually in the minutes range, not seconds.

Some PAS problems are caused by the sensor being too close to or to far from the magnets, but those are not usually reset by a powercycle; they require correcting the spacing to reset them.
 
Has this problem always existed, or did it suddenly start; if the latter, what specifically happened between the time it worked and the time it didn't? Sometimes knowing that will help narrow down possible causes.
The problem "just happened" the last time I used it.
I store it in the garage and as far as I know nothing has happened to it.

Does it happen only at one specific location on the streets, or at any point where you stop pedalling for a few seconds? Is it intermittent, or every time?
Does it happen if you stop pedalling only for say, one crank rotation time? (meaning, you just pause in pedalling for a second or less).
No, everywhere.
I would say that it happens if I stop to pedal for a few seconds and at no special location.

Does pedalling backwards cause it as well?
The bike has pedal brake but the result is the same as if I stop to pedal.

Does it matter what level your battery is at, or does this problem happen at full, empty, and everywhere between?
Since it just started I have only noted it at full charge. I usually pick up and leave the kids at kindergarden, so the bike are only used at irregular times.

Does it happen the same if you flip the bike upside down and move the pedals with your hands, with the wheels in the air?
I'll have to get back to you on that one.
 
I did some more testigt on the way to work.

Like clockwork, the pedal assist stops working if I stop to pedal and just roll for 4 seconds. If I roll for 3 seconds it re-engages as it should.

I had two co-workers lift the bike of the ground and tried again.
And as before, 4 seconds and it stops working.
 
Some hypothesizing below, since there isn't a definite specific failure these symptoms point to.

It sounds like the controller is "going to sleep"; timing out, after those four seconds. There are systems that timeout after detecting no wheel movement for a minute or two, to save power and for safety. But I haven't personally run into one that times out for lack of pedal movement (doesn't mean they don't exist). If yours is one of these, but had previously had this setting to "disabled" (probably a factory setting), this setting may have changed.

If you turn on the bike, then don't pedal or do anything at all for that time, does it also fail to work normally until power-cycled? If not, it may not be a "simple" timeout of the whole system, and instead something specific to the pedal sensor subsystem (though probably still inside the controller).


Most timeouts are within the controller itself, and may have a timer setting available to change within the display menus (if any). These settings shouldn't just change by themselves, but there are a few causes of such changes (poor software design, faulty eeproms storing them, cosmic rays (or other particle radiation sources) damaging the memory location it was stored at, etc.).

Sometimes you can reset this setting if there are user-accessible menus for it, but most of the time there are not. If that's the case you may have to replace the controller (probably the display at the same time for compatibility if you can't get the identical controller).

If you have menu settings but not one for this issue, it might be possible to reset all the menus to defaults if there is a menu for that (probably isn't, more likely requires external factory software and connection to a computer). If you do have this option, write down every setting in every menu you can access, so you can change them back if you have to to get the same operation you had before.


It's possible (unlikely) that if you ahve a plastic disc of magnets on the pedal crankshaft, and a sensor mounted on the frame near it, that the sensor and disc are too close or too far apart, by just a mm or few, and changing that may fix the issue.

I can't think of any other hardware issues that would cause this; if it was a wheelspeed sensor you would have noticed that you get no speed reading on your display.
 
My controller only have a power-on button and "+-" for speed increase. No display and thus no settings menu.

If it is the controller it could accually be a good thing. A new controller and display isn't that expensive as long as the battery and motor is fine.
That is probably cheaper than having the selling company troubleshoot and repair it.
 
Out of curiousity.
My bike is a "lady-model" 7 gear bike and I saw a local add for a cheap Scott MTB.
If I manage to find a new controller box or get it fixed, how much work is it to put the electric parts on the scott frame?

In my mind there should be no problem as long as the front wheel with the motor fits.
 
Callmenobody said:
Out of curiousity.
My bike is a "lady-model" 7 gear bike and I saw a local add for a cheap Scott MTB.
If I manage to find a new controller box or get it fixed, how much work is it to put the electric parts on the scott frame?

In my mind there should be no problem as long as the front wheel with the motor fits.

There's probably no reason things wont' transfer over, though you may have to alter brackets for mounting thigns (tube sizes may be different).

The major hurdle is that the front fork may be significantly different, especially at the dropouts, and this may greatly affect how you can mount a front hubmotor. There's a few threads, including The Torque Arm Picture Thread, that cover some of the issues.
 
Back
Top