Electric bike conversion

Jul 31, 2025 Last reply: 11 months ago 25 Replies

Brushed e-bike motor controllers are available from Chinese sources, but understood if you don't want to go there. Most modern e-bike motors are three phase brushless.

I don't parse your units - 20kWh gets you about 80 miles in an electric car (the first Nissan Leaf was 24kWh). Do you maybe mean 20Ah? (at 36 or 48V)

Bromptons put the battery there.

You can get bags that fit over the handlebars and batteries that go inside them. I'm not super keen on bagged batteries unless they have their own internal solid shell, as they aren't very robust in the event of a crash and all the movement tends to stress the wiring. Also batteries there would make the steering heavier.

If it's a brushed motor it's just two-wire DC so you could do that. The brushed motor controllers you can buy on Aliexpress aren't a whole lot more sophisticated - no display, just an input coming from the pedal sensor or a throttle, and used to determine more much to chop the DC. Just a big dimmer really.

I don't think they're allowed to sell them over that if they're for use on the road. Are you sure that's the sustained power?

Theo

With your bike, you can carry a lock and chain.

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It's hard to say what the official price is. If I were to use a thing like this, I'd probably want two.

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And if you're not careful, you could be exceeding the "cargo capacity" of an older road bicycle. Some of the pig-heavy bicycles of today, have a 300lb cargo capacity. Which is still not a lot, but is likely higher than the capacity of older bicycles. My previous bicycle, had a big frame, and the frame snapped near the crank after ten years. Which I would guess, is average for modern crap. A steel frame would not have snapped like that.

There is a person with an electric scooter kind of thing (legality: unknown), and that person has one of the largest locks and chains I've ever seen for a two wheel vehicle. But since it is electric, and is big enough to have a cargo capacity, it's only the nuisance of fitting the chain that would suck.

*******

When I was younger, I went to the iron monger, ti see what they had for chain. I explained to the guy "I need an alloy chain that is hard to cut". He brings me over to a chain barrel (chain stored circularly in barrel). He pulls out a hunk. He starts the oxyacetylene torch next to the barrel and

*cuts the chain like it was butter*. So funny. And after I told him I wanted something that was hard to cut. The look on his face, there was no cognitive dissonance whatsoever :-) The fact he had cut it like butter, did not register on his face.

I agree with the Reddit thread, that the "average" bicycle thief carries mini-bolt-cutters. They are looking for "easy prey" and thinner lock materials. I don't think I've seen any thieves with angle grinders, but that is certainly a realistic possibility (and especially if the materials are taut enough that the grinder can stay in contact).

I have seen a bicycle thief with the full-sized-bolt cutters (long arms, quite heavy to carry). But at some point, the policeman is going to be laying charges based on "attempted theft", just from walking around a bicycle rack while holding huge theft tools. With the mini-bolt-cutters, the thieves I've seen with those, make no effort at all to hide them, as if some legal opinion means they would not get charged. I have seen *two* males, approaching a grocery store bicycle rack, each with mini-bolt-cutters. I could not tell at the time, whether they were a team, or had only showed up at the same time. They only pick on the one grocery store (richer people might bike there). Other stores do not receive the same attention.

But anyway, once you have gone electric, you're now in a different planning domain. Securing the battery to the bicycle, securing the bicycle, are now a matter of the cargo capacity of the ride. And whether you will have any capacity left to haul groceries. On my bicycle (poorly protected), I have around 80lb of capacity left. Push bike. Non-electric. Light cable lock. If I did a front-wheel-conversion, I think I would still have sufficient capacity, to be hauling big-ass chains. A 60 inch chain for me, would not be long enough, so I would likely use two chains. The bicycle racks here, come in all shapes and sizes and a lot of them are no good for big bicycles. I need extra lock length for securing the bicycle.

Paul

If your doctor tells you not to do that, you don't do it :-)

The general advice for athleticism, is if making a life style change (going from sedentary to active), you get an evaluation by a doctor first. Like, say, a stress test. I've had a few of those, I felt good on one, and could have gone further, but the operator looking at the scope said "we stop here". Which means my elevated T-wave bothered her enough, she didn't care exactly how I was feeling. She didn't want to have to scrape me off the treadmill.

I think my limit might be 135, but I'm on a beta blocker. All numbers shift down. The purpose of the beta blocker is to "rest the heart".

I used to think I was healthy -- until one day, I wasn't.

I still cycle. Just not like a madman. and that activity quite easily takes me up to my (stress test) limit.

For a lot of people, the stress test might well be the first time they've ever had their heart evaluated.

Paul

Me too, and two blood clots over in 4 years have left some damage.

Yes you are right, my mistake, 36V 20Ah

Nor did I

Yes I shall see if it all basically works with a 40V 4Ah drill battery I have and then decide how to run it.

I only need to see how the current pedal sensor works and rig it up to a push button.

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