Saturday, June 16, 2018

Conestoga Project 3

Spent today fitting parts from the motor kit to the intended bicycle, a Giant mountain bike.

1. The motor kit is intended to be mounted on a heavyweight cruiser bike. The sort of thing we used to call a "paper boy bike". They don't mention this in the advertising. The pedal cranks have a large outward offset presumably to keep your knees off the motor. The right hand crank has a sprocket welded to it which would be used to drive the bike absent the motor. The sprocket is a 1/2" pitch type which means it won't run with the 12mm (I think) chain that derailleur bikes use. The welded assembly also means that putting a 3-ring chain set onto it is going to be a non-trivial job. I'm about half way through it.

2. The motor is about 8-1/2" tall which means that the mounting plate needs to be way down low in a modern mountain bike. Especially in an aluminum frame bike whose tubes are about twice the diameter of the steel ones of yesteryear.

2 heavy iron castings are clamped to the frame tubes as shown, and the sheet metal motor mount is bolted to them. Some grinding was necessary to get the bracket to fit between the tubes and the forward side slots needed to be lengthened. Likewise, 2 new holes needed to be drilled and tapped into the rear cast iron support piece to get everything to mate up.

3. The motor also is fitted with an air filter and oil filler on the rear side, both of which hit the seat post before the motor mounting bolts will align with slots in the mounting bracket. Assembly procedure seems to be to mount the bracket to the motor, mount the motor and bracket to the iron frame mounts, rotate the motor in from the left side into the frame, then add the 2 saddle plates last. Relocating the motor mounting slots looks like a requirement if I plan to keep the air filter and oil filler plug intact.

4. The drive sprocket is fairly straight forward. 2 thick reinforced rubber spacers go on the inside and outside of the spokes, and bolts clamp the sprocket to the outside.
I added a spacer to hold the sprocket centered on the hub. So far it seems pretty sturdy.

5. Not necessary at this point, but what the heck, I mounted the gas tank. Again the mounting is intended for a steel framed bike with smaller tubing diameter but with a bit of judicious hammer work the supplied brackets fit.

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