I bought a non working folding e-bike from Princess Auto
 

I needed a fuse for my truck and by the entrance they had this bike. I've wanted a folding e-bike for a while and this looked just like what I was looking for. A robust, folding bike with a motor. Only 350 watts but top speed of 32 km/h which is sufficient.

I offered $500 and after calling his boss the associate said that was good.

I checked the battery when I got home. It's 41.5 volts. But what I don't understand is why there's four connectors. I did some research online and read somewhere that two connects are (-) and the other two are (+). But I could only get a voltage reading when I tested the two outside connectors..

Then I read somewhere that the controller turning off is usually a worn battery connection. First I tried unscrewing the socket that contains the four connectors but when I tried pulling it out with a pair of pliers it would only budge a little. So I put the screws back and then tried straightening the connectors with my miniature screwdrivers and voila the bike works!

I took the bike for a ride around the neighborhood. When I pedal a bit it gets up to 20-25 km/h pretty fast. Takes longer to get up to 32 which is the max setting but it gets there. Pedaling doesn't help it's geared too low.

I had to put the bike away because it's pretty fast and I want to put some lights and mirrors before I go for another ride. I'm anxious to get a carrier rack and see how it does pulling my trailer. I like using my bike to go on jobs but crossing the Jacques Cartier bridge with a trailer takes the wind out of me.

I posted a picture of the plug and you can see where I tried pulling it out with pliers. Is it possible to replace that plug or retrofit to something that's easier to fix. I was able to get it working but I broke two of my miniature screwdrivers doing it.


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That's a nice deal. If you stare at battery cases on aliexpress.com, you can probably find some chinese seller selling it. Ypu can often find parts for the popular stuff. Otherwise, you could google back to the biker seller, probably a Canadian outfit?

Worst case, you re-wire the power thru one ot the undamaged pins. They probably use only tow of the four. but the only way to tell is to look on the back of the pins.

What I have done on a battery with a broken connector is to bring out the power thru a cable. Do the same on the bicycle side, and use a power connector,

Good idea. I'll pick up a power connector next time I'm by the electronics store. I'm gonna need more batteries too. I'm only getting about 30 km on a single charge. I need like 100 km of range so I can use this bike for work.

I think the problem is the bike is geared too low. The top speed of 32 km/h is sufficient. But I can't pedal that fast. So I'm letting the motor do all the work which is less fun and cuts down on my range. I don't even use any of the lower gears. The front chainring has 46t. The rear cassette is 14-28. And the tires are 20".

I removed the right pedal arm to see if I could swap the chain ring with another. But it's a single piece. The little disc with the magnets tells the controller when I'm pedalling. But it just slides on and off the axle.

The bottom bracket tube measures just under 4" wide, about 100mm. The axle is about 6.5" wide.

If I could just replace the pedal arm to one with a larger chainring that would be the easiest.
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How much bigger can the chainring get before it interferes with the frame (seat stay)? You might be better off with an 11-? freewheel. If you're at 21 mph with a pedal speed of 90 RPM now, you could increase it to 27 or so mph with an 11 tooth small gear.

At 21 mph I'm way over 100 rpm. I can't even pedal fast enough to keep up with the bike. So it's killing my range.

It looks like there's room for a bigger chainring. You could be right that swapping to a rear cassette will be better. It just seems easier to swap the front gear or now. I just haven't been able to find one. I looked online at used stuff and all people had to sell was whole cranksets. So I'd be stuck with a bottom bracket I don't need and might not even fit.

You're in CA, so I don't know if this will help, but Amazon has a CYSKY square-taper crank with 53T chainring for about $54 US. That would reduce your pedal speed by about 13% for the same speed. The freewheel change would reduce it by about 21%. Good luck.

The freewheel change sounds like a good idea. I checked google and the LBS have some 11-28 gears in stock.

If you don't have one, you'll need a freewheel tool with a center hole large enough to go over your axle.

This is the part I took off. I brought it to the bike shop and the guy said 11 tooth freewheels don't exist. And I can't change to cassette because the motor is in the rear wheel.


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For one, look at the Drift Maniac on Amazon 11-28 or 11-34 in 7-speed. There's many more, that's just the first one I found.

That's the one I just ordered. We'll see if it gets here.