Help debugging rear hub

[stackmac02]

Hello,

I am a novice bike rider and need some advice. I am currently in Israel and was given a Foffa single speed bike that I believe has a pedal assist rear hub. I know nothing about hub or electric bikes. The guy who gave it to me said it needed work for the hub to work. I took the bike out and was surprised to feel that the hub did actually give some type of assist when starting off. I really enjoyed it. I don't know if it was fully working or not but I was excited to use it. The next day I realize indeed the hub must have an issue as there was no pedal assist and almost felt like the bike was harder to ride.

I tried a few shops here where I am at in Tel Aviv, but they all refused to look into it. There are no connections to the hub from what I been reading. I don't see anywhere to charge a battery or even see sensors anywhere. I see no model number or anything.

How can I debug to see how to fix it. If it is fixable?

Sending a few pictures, can send more as well...

Video of it: https://drive.google.com/file/d/1IQv_bZ6ZJS8gd8zhcTDLBGXd4uva7tdw/view?usp=sharing

 

[PCeBiker]

I'm just guessing but maybe it's a self contained motor, generator and battery.
Try pedaling backwards once to switch it from generator to motor.
I had a 2 speed geared hub bike when I was a kid.
I switched gears by pedaling backwards for about ¼ turn of the pedals.
Maybe your bike switches from motor to generator the same way?

It might be a "3-speed hub switch" with power, regenerate and off?

 

[stackmac02]

That's really interesting you say that. I felt like I activated it by pedaling backwards. But when I tried it again the next day it wouldn't activate. I wish I knew how to figure out the model to see if what the issue is.

 

[PCeBiker]

Keep playing with it until you figure out how it operates.

Maybe you have to be moving to get the switch to operate, or maybe stopped?
Maybe you have to pedal further backwards, or a couple rotations of the pedals?
Maybe you are pedaling backwards too far or taking too long?
Maybe you have to be moving and pedal backwards a bit then hold it there until the wheel spins a couple times?
You'll figure it out.

Or maybe the "gear switch" inside has become a little sticky and needs some grease, or the "friction spring" has lost it's tension and needs to be replaced?

 

[stackmac02]

All this is appreciative. I will give all these a shot

 

[PCeBiker]

I had a coaster brake bicycle where the brakes had failed.
It's the kind of brake where you pedal backwards to engage the brakes.
When I pedaled backwards, the pedals just kept spinning around and I had no brakes.
It turned out that "my clutch was slipping".

There is a little spring clip that clips around the axle to provide some friction to activate the clutch and a tab had broken off the "spring clip", so I replaced it, and got it working.

Mine was similar to this design.



My "spring clip" was similar to fig 7 in this picture but it had a tab rising up off of it that had broken off.





Maybe the "clutch is slipping" on your bike.
Try pedaling backwards slower and more gently, or faster and more forcefully to get it to activate.

It may possibly need to be warmer to start slipping, or colder.

You got it to switch once, so if you learn it's quirks, you might be able to get it working good enough to not have to take it apart to try and fix it.

You'd probably have a really hard time finding a replacement part, so you'd probably have to build one or refurbish the old one.

 

[PCeBiker]

It operates like a pawl lever mechanism.
My broken "clutch" mechanism was similar to a broken spring in this picture.



Or as if the orange arms in this picture were broken off or sagging and no longer making contact.



(Coincidentally, my name is Paul. Lol)

 

[stackmac02]

What precautions do I need to take when opening it up?

 

[PCeBiker]

I wouldn't know what to expect to find inside, but open it up slowly and carefully and take as many pictures as possible to help you get it back together.

Try to open up somewhere, where if a small spring or ball-bearing goes flying, you can find it.
Drape some white sheets or something around your workspace and maybe work on the floor to help contain a tiny part if you drop it.

Lay out each part in order the way it came apart and study how the parts connect/interact with each other to try and figure out how it operates.

There should be a visible sign of damage or wear to the part that is broken or worn out.

If it is that "spring clip" thing that's worn, you should be able to check its operation by spinning the sprocket backwards and check the operation.

Don't take anything apart until you inspect it to figure out how it operates.

If it is that spring clip that is slipping, then when the sprocket is rotated backwards, everything just spins and the threaded spiral isn't activated to pull the double tapered part inwards.



What a bunch of YouTube videos on taking apart coaster brakes to give you an idea of what you might find inside your hub.
(I didn't do that. I'm just going from memory.)


You'll need to be careful with the battery that you don't short it out, but that should be relatively safely installed, and you should be able to avoid the battery, or disconnect it from the switch so it won't activate when you mess with the clutch/switch.

It will have a pretty small battery, so the explosion should be small as well. Lol.


Seriously though,.. be careful with the battery !!!

Disconnect it or remove it before you start checking the operation. You don't want it powering up with with you holding it.

 

[PCeBiker]

You could probably quite easily remove the battery and motor and just use the bike as a regular bike.

If you can't remove the motor, you can probably make sure it's stuck in power or off mode, but having it stuck in regeneration mode isn't good.

You would probably always have to pedal harder, and the energy created needs to go somewhere and that can burn out your motor or create sparks.



You could also just play with your bike to get it in power mode by pedaling backwards then make sure that you don't pedal backwards again.

I assume that it would power you along until it ran out of power then it would pedal like a normal bike?

It should only go into regeneration mode if you pedal backwards.

I think that the best thing to do is leave it alone and just try to figure out it's quirks so that you can get it to switch in and out of power mode by pedaling backwards in a way that works.

I've fixed a lot of differt things by not fixing them and just figuring out how to make them work "good enough".

I had a power steering pump that was leaking, but it only leaked when I turned the steering to maximum or I turned the steering wheel when the car was stopped, so I just never did that.
I just added a tiny bit of power steering fluid once or twice a year.
(it's stresses the power steering pump to max it out anyway.)