EBike Conversion On A Budget Uses Skateboard Motor

eBike conversion

[Dave Schneider] has been chasing an electric-bike build for more than 10 years now. When he first started looking into it back in 2009, the cost was prohibitive. But think of how far we’ve come with the availability of motors, electronic speed controllers, and of course battery technology. When revisiting the project this year, he was able to convert a traditional bicycle to electric-drive for around $200.

Electric skateboards paved the way for this hack, as it was an outrunner motor that he chose to use as a friction drive for the rear wheel. The mounting brackets he fabricated clamp onto the chain stay tubes and press the body of the motor against the tire.

The speed of the motor is controlled by a rocker switch on the handlebars, but it’s the sensors in the brake levers that are the neat part. Magnets added to each brake lever are monitored by hall-effect sensors so that the throttle cuts whenever it senses the rider squeezing the front brake (effectively free-wheeling the bike), while the rear brake triggers a regenerative braking function he’s built into the system!

Sure you can buy these bikes, you can even buy conversion kits, but it’s pretty hard to beat the $88 [Dave] spent on the motor when the cost of purpose-built motors is usually several times this figure. The rest is fairly straight-forward, and besides ordering batteries and an electronic speed controller, you likely have the bits you need just waiting for you in your parts bin.

29 thoughts on “EBike Conversion On A Budget Uses Skateboard Motor

  1. I have made myself confident that the motor from a cheap Chinese electric chainsaw would be a better candidate for this kind of contraption, costing around half that price for a classical 300W with shipping costs included

    1. could you use that chainsaw to cut out pieces of bicycle frame? I’m asking because maybe you could save another $2! Srsly, there’s a point where it’s no longer feasible to cut corners (literally, as well), and just buy a mass production e-bike. At this point I’d be more impressed by someone who increases the speed, power and/or efficiency of an exiting e-bike motor.
      I’m also amused my old homestate of Massachusetts has yet to legally define “e-bikes”, I’m sure because everyone there knows it will become a bureaucratic nightmare that will anger most people, no matter what. It seems to be a matter of benign neglect. Maybe a chainsaw motor could somehow legally make it a chainsaw, instead of an e-bike and get around taxes and regulations in certain states? Otherwise I will put e-bike motors on my e-bikes, thank you very much.

  2. “While loitering along, experimenting with the controls, I was passed by a college student on a mountain bike who must have thought this gray-bearded old-timer on a four-decade-old 12-speed was huffing and puffing. So I poured on the juice and blew past him, thereafter maintaining Tour de France speed. As I raced ahead, I chuckled to myself. “OK boomer,” indeed. ”

    Couldn’t help but groan over the closing paragraph. I do the majority of my jaunts on the (pedal power only) treadly out in the hills where you can conveniently avoid almost anyone, but on the way out of the suburbs on the designated bike trails I encounter these dorks with something to prove all the time. They normally fly pass you to recover their dignity after you’ve passed them.
    In a typical encounter I might have been closing in steadily for several kilometers for ten or fifteen minutes, but 60 seconds after I overtake, they fly pass me to regain the lead. My favorites are the ones pass with their bums lifted off the seat, pretending to be peddling strenuously like Tony Rominger, with the electric motor whirring.

      1. The sausage is fine, it’s the nuts that are problematic. Thought with some seat-angle fine-tuning I think that I have reached a balance between aching bum bones and aching nuts that I can live with.

        1. I’d say impotence from bicycle seats qualifies as a sausage problem! It’s not just a matter of “aching”. It’s a matter of affecting performance. I also think you’re mistaking the humorous tone here. It has a basis in truth, (which makes it more funny). Maybe you don’t have a partner at the moment, you might even be a celibate monk for all I know. But I do know there are potentially serious sexual health issues resulting from using traditional bicycle seats. “With their bums lifted off the seat, pretending to be peddling strenuously”. Yeah, pedaling (not peddling) strenuously is not the only reason to ride with bum off seat.

          1. I thought I was continuing the humorous tone!

            Yeah, I’ve been remiss in catching my stupid typos and the auto-corrector bodges, but I’ve been side-tracked tearing my hair out in just trying to get my login and comment submission/entry to work without bugging out. There seems to be a lot of trouble-free activity here, so perhaps I’m a special case, but I’m finding the comments section to be borderline unusable.

            There’s only a ~50% chance a comment will go through on the first attempt without flaking out in my browser or returning an error message. And if there is any hiccup at all when trying to post a comment on the first attempt, a successfully resubmission will result in the comment not appearing where I was intending it to, but at the end of the thread. Even the lamest forums out there give you at least a limited time window to edit or delete a bodged post if posting from a dedicated user login – why not this place? More trivially, why can’t I shift to a new line in the text-entry dialog box by hitting the spacebar? This is an annoyance if the last character of a word happens to be in the last character position of a line.

            Incidentally, I have a Hackaday IO login, but that area looks to be about as enjoyable to navigate as would be chowing down a bowl of cold and mushy Brussels sprouts, such that I can’t see myself getting motivated to use it in its current form. This place is supposed to be by and for the tech savvy, so why is the human interface so lousy?

          2. “But I do know there are potentially serious sexual health issues resulting from using traditional bicycle seats.”

            This is a myth that has long since been disproven and I assure you, there are plenty of cyclists out there with *very* happy partners.

  3. I find a ton of power wheels just laying in the trash. I’ve already tore one down for it’s motors and transmission… just looking for a project to use em… i was thinking about possibly putting them on a canoe for a nice quiet propulsion. or maybe on a bike trailer so the extra weight will haul itself.

  4. Since your using an Arduino, you could use the UART interface and talked to the controller by setting it with RPM instead of current. That would have given a more consistent speed.

    1. Setting a speed on an electric vehicle works badly. Your motor-control-system (ESC) will apply max power to reach that speed and the moment it reaches that speed it stops accelerating. This gives a jolt-feeling to the user at both the start and stop of the high-power-part. For a internal combustion engine car this is less of a problem: the cruise control system flooring the accelerator will not immediately provide max power. It does in the case of electric. And they programmed it to avoid this situation.

      A throttle-to-current setting on the ESC works best. Feels natural.

  5. Brake sensors can be used also to remind about checking the brakes before each ride. There could be a notification after switching on/unlocking/when the wheel starts rotating. After pressing each brake knob (assuming that user has checked that it causes braking) the notification would be stopped.

  6. That’s certainly a nice clean economical build!

    Friction drives are notoriously inefficient. They add a lot of drag when you’re not using the motor. Many years ago, Bob Schneeviess came up with a scheme that mounted the motor on a hinge. When the motor wasn’t powered, gravity or a spring rotated it away from the tire. When you powered the motor, reaction torque rotated it enough to touch the tire. Then, since the motor is rotating faster than the tire, it pivoted to be tighter against the tire. The greater the motor torque, the tighter it swung into the tire.

    This was a very successful technique, widely copied on various Ebikes. The EV Warrior used it, for example.

    1. Nearly 30 years ago now, I fitted dynamo-powered lights to my lightweight 12-speed racer – a bike almost identical to the one in this article. The dynamo was friction driven off the rear wheel rim and I remember being surprised at just how much more leg effort was required to move at speed when the thing was engaged.

      That rigid-mounted/fixed skateboard motor must be exerting a lot of pressure against the tyre and I wonder just how much extra leg effort is required to move along at a decent pace on a flat battery. The mechanical simplicity is nice and all, but I’d want a lever to allow me to disengage the thing when propelling myself conventionally.

      1. Alternatively, motor can power the chain through some sprocket – it would be more efficient. It should be powered only when pedalling, but it’s already required by e-bike traffic rules in some countries. It would be interesting how to add extra torque to support in pedalling, but decrease it or turn it off, so it won’t keep the pedals spinning itself.

    2. Not only are they inefficient, they destroy tires lickedy-split. A quality commuter bike tire can be $60+ (and normally last many, many years.)

      They also don’t work when it starts to rain.

      Mid-drive kits are super popular right now for a reason. They by and large bolt on.

      The expensive part isn’t really the motor or controller. It’s the battery.

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