Construction
Attaching the Spindle
The 1.25 inch spindle with a threaded hole that I used on my bike is a peg which came with my all-terrain scooter. The shaft was already threaded so the spindle was easily tightened onto the shaft and secured with two more nuts. In a spindle driven design, the spindle is the only determiner of the effective gearing of the bike (the tire diameter doesn’t matter.) A 1.25 inch spindle works well on this bike as a nice middle ground between top speed and acceleration. It would still be interesting to try out some other sizes.
Strapping on the Engine
My engine came completely encased in plastic shrouds. Once the engine was free from its casings it was possible to lay out a pattern for the engine mount. I rough cut the holes for the flywheel and coil so I could layout the pattern of the screws. This engine has a cast bracket perpendicular to the shaft which made it easy to screw to the 1/4 inch plywood plate. The thickness of that plate was my first mistake. Thicker plywood would have been much better for this purpose for reasons I will explain further down the page.
With the engine screwed securely to the plywood, I continued by making brackets to connect the plywood to the bikes front fork. These brackets bolt around the front fork, through the plywood and to a set of flat brackets with 5/16 inch bolts. The Brackets are able to tighten down on the fork so there is enough tension to hold the spindle to the wheel.
At this point, I took the bike on its first test run, which didn’t last very long at all. Actually, more accurately, it never started. The 1/4 inch plate tended to bend rather than engage the tire. I couldn’t get enough traction to kick over the engine. Hence why thicker 1/2 inch plywood, or even better 3/4 inch, would be much more effective. To stop the plywood from bending without starting over, I used more aluminum strapping bolted to the face of the plywood. Amazingly, this worked! With some furious pedaling I kicked the bike over and the motor started, rocketing me to the end of my street. This was very surprising and quite exciting to me since most of my frustration ridden second attempts tend not to work out.
