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e-Zündapp: A conversion of a classic moped

SimonKagstrom

🧲 New user
Joined
Aug 14, 2026
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6
Location
Sweden
Hi!

I've done (well, are these things ever finished?) an electric conversion of a classic moped. It actually consists of parts from here and there, but most are from Zündapp, so I'm saying it's a Zündapp. It also says so on the gas tank, which by the Swedish saying is what counts ("det är tanken som räknas")! I bought it in a good condition without the original engine, so most of the bike styling is not thanks to me.

The mopeds from the 70s/80s were capped at 30 km/h, which was also my target speed for the conversion. It comfortably does 30 km/h, and I'd say it oomph-wise feels like a 50cc two-stroke moped from the era, although I have little actual experience with them.


It's based on a VESC controller, the Spintend single UBOX 100V / 100A and uses a Vevor 1800W motor for the true lethargic 50cc 1hp feeling. I've coupled it with a 52v em3ev king shark battery, basically an e-bike-style battery mounted between the frame and the front wheel. Lights have been converted to 12V and are driven via the Spintend adapter board.

Now, I'm a software developer, so I've also done a ESP32P4-based display for the VESC controller (link to another thread on this forum) to show the speed, the position on a map and trip data. That's were I've put in most work, and it's also what I'll keep on developing. It sits in a rectangular 3D-printed case on the handlebar, which is sort of crude but I'd also say fits fairly well with how the speedometers looked on these. At least it's as good as I can make it!


Conversion-wise, I got help from a friend who works as a mechanical engineer to design the motor mount adaptors (thanks David Ålind!). I went through many iterations of 3D-printed ones before ordering them in steel, and I think in the end it turned out just fine. There are also a lot of other 3D-printed parts on the moped, and what a revolution it is to be able to do that!

So far, I've done about 100km on the moped. It's slow, but that's also how I intended it to be (and 8 tooth front / 42 rear helps with the slow starts). The motor and chain is slightly noisy, which I think is partially due to VESC configuration and partially due to the small 8 tooth front sprocket. My back don't quite agree with the low position of the handlebars, so it's a bit uncomfortable to ride for longer times. I won't ride it very far and often, so I don't mind too much. I mean, it's mainly an excuse to do a software project after all!



Links to some more information about the project (including to the OnShape CAD work), and the source code and more information about the VESC display

GitHub - SimonKagstrom/e-zundapp: Electric moped stuff
GitHub - SimonKagstrom/radbuzz: Infotainment for a VESC-based electric moped

left_back.jpgright_back.jpgright_side.jpg
 
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Sweet bike. Lots of potential for future upgradability. Lol

Haha! Yes, I agree!

I'll focus on the display though, which is what I'll likely do best. But apart from that: more ergonomic handlebars/clip-ons, a more cafe racer style of seat and new and matched tyres.

Indeed, there's lots to do. Knowing myself, I'll just work on the display. :)
 
Excessive noise is to be expected from a 8T sprocket. Also high wear.

I know! I've been looking for sprockets, but found no fits for the bolt pattern it has. Went with 8t to get at least sort of reasonable gear ratio.

I've also designed an adapter to fit another rear sprocket, but a bit too tight fit, and not sure how well it will really work out.

The vevor motor also seems to have a bit limited supply of 415/420 sprockets.


For now I'll go with excessive wear, since I don't ride much or very long anyway.
 
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