RC Gear on Bikes?

[Dave]

I've been planning a recumbent project with my kids, and while looking around for information on that, bumped into a page (link) where the author used a motor and controller designed for a model airplane or helicopter to power his recumbent bike. The motor is a 4000 watt AXI 5345 brushless motor (later replaced by a 5320), and the controller is built by Castle Creations; a Phoenix HV110. The motor spins at about 10,000rpm at the 48 volts he uses, but he has it geared down for a maximum speed of about 30 mph. The motor has enough torque to get him to max speed in about 5 seconds!

The author -- Matt S. -- says that the typical controller supplied by ebike manufacturers is pretty old technology (looking at my Golden controller, I can easily believe that) and that the controllers used in RC kits far outshine kit from the likes of Golden. The controller he used looks to be less than 1/4 the bulk of the Golden controller I have, doesn't have heat dissipation issues, and is even programmable via a USB connection to a computer, giving control over all manner of parameters. You can even make it do regenerative braking. The best part is that these motors & controllers don't seem to care how much input voltage you apply to them, up to a 50V max. The higher the voltage, the faster the motor spins. The motor speeds are even rated at a per-volt figure.

It was really refreshing to see what this guy was able to accomplish with off-the-shelf parts from a totally different field of equipment; shows that the current crop of ebike gear isn't quite the state of the art, and it's possible to power a bike with a smaller/lighter motor and smaller/lighter controller. Matt's project definitely isn't for everybody, as a lot of the parts had to be custom fabricated. For the average person it would mean a lot of money spent at a machine shop. (Matt has a home machine shop(!) that makes me green with envy. Man, if I had access to a CNC machine, or even a manual 3-axis mill, there would be a whole lot less dreaming and a whole lot more doing going on at my house.)

These controllers look to be way more expensive than those available through Golden, but I'm thinking that the smaller size, the programability, better efficiency, etc... might make them a good alternative. That's IF one of these controllers would work for my Golden Motor; I'm thinking probably not, as there are no inputs on the controller for the Hall sensors. Even if they won't work, seeing what Matt did with his bike gives me all kinds of ideas for my next project...

Anybody have any experience with electric RC motors & controllers to know whether these controllers would be compatible with the Golden hub motors?

[Mel in HI]

I can't believe how much work this guy went through for this.  Definately a guy with lots of time on his hands. 

I actually like the recumbant design as it puts the weight right under your but, which I would imagine would be good for balance.  The thing I think would be bad is that he mentions that he is going to be charging/balancing each cell one at a time.  I wonder if that's a mistake in what I am reading, or if he is actually doing that?  Sounds like a LOT more work on this bike than most anyone would be willing to do.

[cerewa]

I looked at that project. He made an awesome bike but it's possible to make a good one with less work and less complexity.

Some of those RC motors have enough torque to pull a bike using only one gear-reduction (instead of 2) provided you don't need 4000 watts and will go with a more typical power level (500 or 750 watts).

The thing I can't figure out is how one adds a gear (to pull a chain or belt) to those RC motors. I'm sure it's easy for a skilled machinist, but for the rest of us?