Cycle Power, Part II

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Combine a bicycle, a battery, and an automobile alternator... and you can pedal up some watts in your own home!

In the last issue of this publication (MOTHER NO. 67) we showed you how to turn a bicycle into a stable mechanical power source that could readily be connected to a number of different tools, and then we proceeded to describe how you might hook the unit to a water pump. Now, as promised in that first installment, we're going to tell you how to generate electricity ... by combining the cycle-power chassis and an automotive alternator.

EVOLUTION

As is often the case in research, while we were busy designing the new package, our team made a few improvements to the original setup. Foremost was the addition of a flywheel, which has helped to stabilize the pulses that are produced by the thrusts of the rider's legs.

We decided to use a junked Volkswagen flywheel for a number of different reasons: First, we had one lying around the shop ... second, it has a flat surface, next to the ring gear, upon which a belt can ride ... and third, the unit's onepiece construction (which includes anondetachable ring gear) and recessed face make the VW bug part nearly impossible to repair, a fact that has made numbers of used flywheels available for next to nothing.

To install the steel disk, we simply welded it—centered—on our Raleigh's rear hub. Then, in order to provide clearance for the flywheel, we had to relocate the rear frame braces. The upper 19-1/2" conduit crosspiece was moved 5 inches—to a point 24-1/2 inches up the frame tubes—and we added two braces, which run between the axle ends and the bolts that connect the horizontal and vertical frame members. The combination has increased the chassis's rigidity.

Furthermore, the roughly 12"-diameter disk allows for a greater ratio increase than did the old chain and 6" pulley system. In fact—after experimenting with different drive pulley sizes on the alternator—we've found that our new flywheel, teamed with the stock 3" pulley, seems to provide a close-to-ideal ratio.

WIRING

Attaching the car alternator to our cycle-power frame involved only minor modifications to the basic bicycle unit. A 6" piece of 1" angle iron was bolted to the angle iron braces on the chassis, and brackets were then fashioned to allow the generator to pivot (to provide belt tensioning capability). Then we attached an 18"-piece of all-thread to one of the alternator's mounting bosses, and slipped the other end through a hole in a steel tab bolted to the column that supports the bike's seat. By threading two nuts up or down the all-thread, we can quickly adjust the belt's tightness.