Framebuilders - making my own motor frame for the fork

I am not sure where to post this...it is re: electric but it is also directly related to frame strength so I thought here would be best.

I would like to install an electric motor on the front of my bicycle. I do not want to use a hub motor but rather a standard motor that will mount on the frame and connect to the wheel with a chain. I was just looking in a bike store and noticed that the custom forks have "nubbies" to install a center pull brake and also have a place designed to install a disk brake. I was planning on installing a disk brake - I think would do better at higher speeds. That leaves the two nubbies free. I would like to have a metal collar fabricated to fit over the nubbies. It will be two pieces. One on the front, that will surround the nubbies and one on the back side of the fork. They will connect with bolts. This collar will serve as a platform to mount the motor.

I have no way to draw a picture but I am hoping that I am clear enough so that any of you who have any skill in this kind of work to understand.

Do you think this will work? Do you think a fork with nubbies was designed to withstand stress at these points? The motor will be a 300-350 watt, 48 volt motor. I am going to install a 3 or 5 speed hub gear in the hub of the wheel to help make the motor more efficient.

How complex of a fabrication job do you think this is? It does not have to be beautiful but strong, and free of any sharp burrs, etc. Can anyone recommend thicknesses of metal to use?

Thanks!

About 15 years ago a friend named John Burchard in Rialto, Ca. made a front fork for his bike that used a chainsaw or leaf blower engine - not sure exactly what the donor was. The engine drove the front wheel thru a chain like you describe. I don't know if he used a freewheel or not. I suspect not. I think he used a centrifugal clutch. Anyhoo, the thing was not as heavy as I expected and cruised at around 35 mph. I know everyone want's to go green now, but unless you're charging your battery with solar power you are only transferring the burning of fuel to the power plant. It might be more effecient and green to use an engine that could burn a biofuel. Can you imagine a small fork mounted diesel engine that runs on recycled food frying oil? Now that would be a hoot.
But I digress: I suggest you acquire a second fork that could be dedicated to the electric motor. That way you could weld a strong stable platform for the motor directly to the fork and not rely on using attachment points that were not designed for the task at hand.

Thanks! What kind of metal is most suitable for welding? I thought the common steel forks would be more suitable but the chrommoly forks are stronger. Any suggestions? Is welding something to a fork a tricky project?

Welding to a chrome moly fork isn't all that tricky. I do suggest you have it done by an experienced welder. I would use oxy-acetene or TIG. I'm pretty sure friend John used a wire fed welder because his shop built NASCAR racers and the place had several wire welders. Brazing your attachments to the fork is also a good way to do it. I think brazing might be less likely to warp the forks but don't know for sure. I've brazed lots of attachment things to Reynolds 531 frames with hi-temp silver solder and never had a problem.

Thanks!