Boost Around Town With This 3D Printed Bicycle Assist

[MechEngineerMike]’s bike boost is just a pleasure to look at, and, we’re certain, a relief to use. While it’s not going to rocket you down the street, it will certainly take some of the pain away. (Just like the professionals!)

It’s one thing to design a device that can fit one bicycle. It’s quite another feat if it can support multiple frames. On top of that, it’s even simple. It attaches at one point and transfers the power to the wheel easily. There’s even just one wire to connect, an RCA cable, to engage the boost.

We really like the clever way [Mike] used the rotating shell of an outrunner motor as the surface that presses against the wheel. We wonder if a cast polyurethane rubber tire for the motor would help, or just help overheat the motor?

The parts for the device are 3D printed and pretty chunky. They should hold up. Check out the video of it boosting [Mike] to the grocery store, where he can, presumably, buy less with all the calories he saved after the break.

22 thoughts on “Boost Around Town With This 3D Printed Bicycle Assist

  1. Yu don’t need 4000.- for an ebike nor 1500.- for a conversion kit… It’s a nice design but not very practical (as every friction drive) as it works only under “perfect” conditions… If you want something reliable.. get a 250W front hub wheel for 150.- and you’ll be able to use it with any tire under any conditions…

      1. You can try Greentime on Aliexpress. I know it’s a chinese source but I have ordered from them several times and never had any issues. Or try the Endless Sphere forum and browse in the “used stuff for sale” area.

        1. Definitely go to endless sphere to seek for advice. There are numerous possibilities.
          Some bikes, are not compatible with all the kit.
          Most common brand for the motor hub are bafang, 9 continent, crystalyte.

          I’ve heard that the friction motor have a very bad efficiency, and it reduce the life of the tire.
          For a plug and play setup, I would have gone for a crank mounted directly on the chain.

  2. For a friction drive, you need one hard surface and one soft, sticky one. It doesn’t help to have two sticky surfaces, and as you say, it could just reduce motor cooling. Also, motors for R/C models are generally designed to put out their maximum power at high RPM, so putting a bigger “tire” on it would just mean choosing a lower-RPM motor. I think he did it just right.

    I’m not seeing a lot of space for batteries. Wonder how much range it has.

    1. Looks like enough range. With a 660W power and a relatively fast spinning motor, this is going to be more of an “after burner” assist. I.e. best for keeping up with tight traffic, or erasing the worst hills from a ride while you still provide the majority of the energy during a ride.

      I’d expect the friction drive to retain some functionality in the rain. Last I looked for estimates, wet rubber still gave a coefficient of friction of ~0.4 on a rough surface when wet. (down from 0.8-0.9 when dry) Friction probably gets a lot less if the motor can starts slipping when wet. Maybe traction control is needed between the drive motor and tire.

  3. Love it. Awesome design and very good implementation. A cast rubber wheel will change the ratio of the motor however. Will it make a difference? Wont know until you try. With that said, great use of technology and parts. Should be able to sustain a fairly long lifecycle, as well as easily serviced.

    1. It’s a long tradition, selling plans for projects, and $10 isn’t out of line. If it’s worth $10 to you to have the complete plans, go for it. If not, you can re-create his project from scratch. Why act shocked about this?

    2. LOL perhaps you and Ms. Phoenix Perry can convert him to see the light of “free”, or not purchase what he offers for sale if he is not willing to see the light.

    1. Put it on Kickstarter, form a partnership with a financial expert to manufacture it, watch your dream go down the drain as the partner builds a house with company funds.

  4. Funny, maybe cute, nice “educational project”, well designed, simple yet poor efficiency.

    Here in Portugal there are already one (that im aware of) maybe more producing and selling rear hubs (with inner electric motors) from 250w to 1000w. You only have to add batteries and a sort of control… Assuming you don’t buy the rtr package. And it works with every bike, well maybe there are some differences according to hub with, or you have that kind of cruiser ugly electric assisted bicycles from the all sports shop..

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