Motobecane 50V Restomod/EV conversion

Hey gang, I've got what I believe (the VIN plate is quite faded) is a 1970 Motobecane 50V... well, really it's the Canadian N50 but as I understand they're basically the same. I bought it off a guy who wasn't the original owner. He had a plan to rebuild it a long time ago. He stripped some parts off, took the engine out and somehow lost it (how do you lose an engine?) and then it sat in storage for who knows how long. I found a lot of old vines around the drivetrain so I think he's using the term "storage" pretty loosely.

Its current state:

The frame and bodywork look to be in okay-ish condition with not too much rust. Not sure what state the inside of the gas tank is in, but I suspect it's not great. Front and rear fenders are both there and in decent condition. It's missing the chain guards, but It looks like replacements are easily found online.

The rear shocks are quite rusted (I'll try to salvage them with an electrolysis bath). The front and rear brakes will definitely need to be replaced. I'm hoping the front forks can be cleaned up and aren't too far gone.

The headlight is in decent shape, the shroud is a little rusted but can be brought back to life. The lower plastic grill is cracked, but I looked quickly online and I think that can be replaced. The taillight looks pristine. Probably the best part on the whole bike!

The speedometer bezel is extremely rusted and the numbers on the gauge have faded. I quickly shot some lube in the speedo cable and was able to move the needle with a drill so I might try to restore that if I'm feeling ambitious.

The plan:

I want to give this moped a second life and build it as a city commuter for my wife to go back and forth to work (about 20km round trip). That means it needs to...

1) Be extremely easy to operate.

2) Look great.

To accomplish the first point, I'm going to convert the bike to electric. So no two-stroke braapp unfortunately. I know, I know... please don't ban me from the forum for this.

To accomplish the second point, I'm going to preserve as much from the original as possible, simplifying the drivetrain and concealing the battery/electronics into the bike's design.

Ideally, I'd like to use a rear hub motor. This would eliminate the need for any chain or pully on the left side of the bike and free up space where the gas engine would mount. I do still need the freewheel connected to the pedals on the right side to make it legal, but that's easy enough.

The first issue I've got to solve is I need a dropout width of 150mm and the stock swingarm is 125mm. That seems a bit far to reasonably stretch and I would like to avoid chopping and welding a perfectly good swingarm that someone else could use.

Does anyone know if there's a wider swingarm that would work on the 50? Maybe something like this? https://www.treatland.tv/MLM-motobecane-MBK-51-style-race-swingarm-p/swingarm-894-and-pegs-893.htm

Oh, here's a few shots of the bike in it's current shape...

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Re: Motobecane 50V Restomod/EV conversion

Awesome! Sounds great, yeah if you do a nice looking battery holder where the engine was I think it could be really sharp. Moby chrome in general is crap so if you really want it to look nice, you'll probably need to source replacement, but keep us posted on how electrolysis goes.

As for stretching the swingarm I think you'll be fine. It's got no value for anyone as a spare so don't sweat that. I have a large 3/4" bolt and coupling nut that I use with wood blocks, like a mini screw jack. You'll be surprised at how flimsy and easy to bend they are in that direction.

Otherwise, just cut new metal plates and weld them on. If you bolt the wheel into place and center it before you weld, it will be fine. Obviously you want the wheel straight but it's not that precise to be honest.

Re: Motobecane 50V Restomod/EV conversion

That chrome can be saved follow my guide

https://www.mopedarmy.com/wiki/How_to_restore_vintage_chrome

Re: Motobecane 50V Restomod/EV conversion

Yeah, I'm hoping to fit the battery where the engine was and make a cover that helps it blend in. If that won't fit, my backup plan is to build a small wooden crate to sit on the back with a false bottom that hides everything.

Thanks for the swingarm info. Once my EV components arrive I'll give the stretching a shot and won't feel so bad about doing it.

Re: Motobecane 50V Restomod/EV conversion

This is great. Thanks!

Re: Motobecane 50V Restomod/EV conversion

I am looking forward to seeing how the wheel motor retrofit goes. I am contemplating doing this to my Honda Hobbit. Although, it is in great condition, I am on a kick for electric vehicles. I just completed an electric go kart conversion with my son, and it turned out great. I would like to know that the hub motor is feasible, and learn from your project before making my own plan.

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