New bike does not work.

[Ackvoke]

I have just purchased a new folding fat bike for my wife but it does not ride like my neighbours.
We wanted two bikes but were unsure of the size because of the extra weight. so we ordered one to see which way to go.
On receipt the bike surges forward on pedal assist and continues to run for a few seconds after the pedalling has stopped, very dangerous!
My wife is therefore, not allowed to ride it.
the throttle control is perfect and we are most pleased with the general build and quality.
can someone tell me if this is a quick fix problem caused by my lack of understanding or do I need to pursue a long distance claim with the Chinese manufacturers?

 

[tomjasz]

Where did you buy and from whom? The brake cutouts should kill the motor until you sort the malfunvtion. Do you have a manual for the display? Is it programmable?

Brand and model of bike. Its hard to help without information!

 

[AHicks]

I have just purchased a new folding fat bike for my wife but it does not ride like my neighbours.
We wanted two bikes but were unsure of the size because of the extra weight. so we ordered one to see which way to go.
On receipt the bike surges forward on pedal assist and continues to run for a few seconds after the pedalling has stopped, very dangerous!
My wife is therefore, not allowed to ride it.
the throttle control is perfect and we are most pleased with the general build and quality.
can someone tell me if this is a quick fix problem caused by my lack of understanding or do I need to pursue a long distance claim with the Chinese manufacturers?

Not a very good chance of a "quick fix".
I can tell you that pedal assist (PAS) related problems, especially those noted most at low speeds, are VERY VERY common with the controllers most often paired up with hub driven bikes.

A few guys that really like the bike otherwise, and don't mind the DIY involved for a solution, will go with an aftermarket controller, most often ones made by KT (Kunteng). It's a WAY more sophisticated controller that's made many friends.

Until you come up with what you are going to do, it may be possible to simply unplug the PAS sensor, located down between the crank arms. That should shut down the PAS but let the bike remain functional using just the throttle. Best of luck.

 

[Ackvoke]

The bike was purchased in Europe, a Philodo H4. The display is programmable and I have adjusted the speed to 25k, the PAS sensitivity to 1, the PAS strength to 1 and the pedal assist from its default of 5 to 3. I did notice this last adjustment was a choice of 3, 5 or 9 and not consecutive numbers.
You are correct, the brakes do cut the violent acceleration and I have used them whilst testing. I have ridden motorcycles all my life and find it possible to accommodate the unusual behaviour however, I think my wife without this experience would be at risk.
One other noticeable quirk, it takes around eight pedal strokes before the motor cuts in and accelerates to about 14k. My neighbours bike cuts in on the first stroke.
the bike goes much faster than I am pedalling, that is, as long as the pedals revolve slowly it will maintain 14k.
All this is on a flat road of course.

 

[AHicks]

Interesting. OK some WAGS.
1st, "sensitivity" could easily be how far the crank must be turned prior to power being turned on.
2nd, generally, people experiencing "too fast" that have the 3,5,9 PAS level choice, can slow it down best using PAS 1 of 9.

That "much faster than I am pedaling" is what I was talking about regarding the most common complaint/reason for trying PAS 1 of 9.

If your OK messing with it, that's what I would do, at least until I could get my head wrapped around the options you have.

 

[Ackvoke]

That's quite interesting, Today being Sunday, we have a market and BBQ organised with friends so I will try altering the two sensitivity parameters tomorrow and see if one alters the crank/power position.
I looked at the KT controller but it looks like I would need to change the display as well. it also says it is for square sine wave and I don't know what Iv'e have, there is more investigation required before I can take that route.
Talk to you after I verify the alteration to crank position.
Thanks .

 

[rich c]

Sounds like it works to me. You describe a normal pedal cadence sensor action. You can limit the power continuing after stoping the pedals by feathering the brakes. The brakes have a motor inhibitor switch that instantly shuts off the motor. Cadence sensors aren't smooth in their power application. You have to look into reprogramming the controller through the display. Buying direct from China makes you the mechanic, the troubleshooter, and the tuner. That doesn't work for a lot of people.