What is the part that controls how responsive / lag there is for motor to kick in once start pedalling?

[gembike223]

i have used ebike and everything seems good except that i dont like this aspect of it:

- Once i start pedalling, it takes about ~2 full revolutions to start the motor. and also when i stop pedalling, it takes about 2 full seconds to have the motor cut off. to me, this lag is too much and i'd like it to be about 2-3x more responsive, i hope that makes sense.

- if i press brake, it does cut off in an instant, so i think the motor is capable... is this the controller? the cadence sensor? can this be adjusted or do i need to get an all new part altogether?

Thanks!

 

[indianajo]

It is not a part, it is a program in the controller. If it assists at all, the magnet pickup on the crank is working.
Because people like me pedal the crank backward to start off with the pedal near the top, the programmers have to leave it idle for 1/2 revolution to keep from whacking the rider in the back of the leg with the pedal. 2 revolutions is a little much. there might be some parameter in the controller you can modify, but mine had 46 parameter with no instructions, so I was afraid to mess with it. Most parameters, if you get it wrong the motor doesn't work at all. If you detail what brand bike what model and what year, a couple of the bike shop owners might respond with detailed instructions. But most controllers are not famous and not well documented.
As an alternate, your pickup may be too far from the magnet plate and it is only picking up one or two magnets out of 6 or 12. Take a look down there and see if the pickup is about a sheet a paper away from the magnet plate all around the revolutions of the crank. Maybe a 16th inch max. Crooked magnet plate with a varying gap would be a sign of what is really wrong.
I gave up on pedal assist (PAS) and went to throttle only when i moved the controller + motor to another bicycle. Saved me buying a special tool to take the crank off and install the magnet plate. My PAS was too jerky, accelerated too fast and wouldn't go slow enough (11 mph minimum) for my uses.
Best of luck.

 

[gembike223]

" Crooked magnet plate with a varying gap would be a sign of what is really wrong." THANK YOU, that's EXACTLY what is going on here. Please see:

Also, i'm experiencing what exactly you describe: "My PAS was too jerky, accelerated too fast and wouldn't go slow enough (11 mph minimum) for my uses." I almost feel the power settings are set way too strong to ramp up.

ALSO, for my future reference, if I exchange my current 6 magnet cadence sensor for 12 (or more) magnet cadence sensor OR a torque sensor, would I also see a difference in motor response time?



My motor :

 

[indianajo]

I'd just straighten up the existing magnet plate. the 1/2 turn rule means 6 magnet plates start after 3 magnets pass. 12 magnet plates start after 6 magnets past. You probably can't change the settings of the controller, so don't change the # of magnets.
I had a non-standard 90's one piece crank originally, so I opened up the hole in the plate with a grinder to get it onto the crank, then filled the gap with splinters of wood and 3M weatherstrip adhesive. You may be able to do something similar if your magnet plate is not actually warped - just crooked on the shaft.
That looks like a generic cheap geared hub motor. Mine was ebikeling, but there are hundred other vendors. Mine lasted about 4500 miles before a plastic gear wore out.