Hello Tcam, in order for the high RPM of the engine to turn the very large rear wheel of a bicycle, you need a whole bunch of reduction.
If my memory serves me correctly, the crank gear of the common Garden Variety Chinese 2-stroke is 21 teeth, and the ring gear in the clutch 82 teeth. this would make a 3.90 to 1 ratio. Then you have 10 to 44 which is 4.4 to 1.
When the ratios are multiplied you will get 17.16 to one revolution of the engine. I have an RPM caclutor on my site here
Simpson Motor Bikes that would allow you to figure road speed, at rpm.
Obviously you could never spin the wheel every time the crankshaft spins unless your rear wheel was about 2" diameter. With this in mine, the output of a normal 4-stroke engine is actually the end of the crankshaft, so we have to provide external reduction, and that is the weak spot of almost every 4-stroke in use on Motor Bicycles today. It was an "Ill-Famed" Hoot, that caused me to begin experimenting, and building, and caused the creation of EZ Motorbike Inc.
Of the in-frame reductions now in use, there are several continuing complaints by most owners, and an insidious problem that most are not aware of. What, you will probably be asking yourself at this point are the problems? The first problem is excessive noise, growling, howling screeching noises.
BTW, for inquiring minds, YES, that noise does represent significant power loss, do to the lost power to spin those poorly meshed components. The Insidious problem you ask??? Well, even IF the noise level in the China-Box is acceptable, (and some are), there is a lot of power-robbing action in play inside that box.
Between centrifugal mass, friction of meshing teeth, and the load caused by running in grease or oil, you will lose an appreciable amount of power and speed right in the Primary. Just think of walking in the sand at the beach being the teeth meshing and now walk out waist-deep in the water, for the oil in the box. I'm A-fear'ed we ain't in Kansas anymore Toto!
EZM Inc. excels in design and application, and has a real-world solution to the Primary box for today's Motor Bicycles. We are the first American company to step up, design, test, and produce low-loss, QUIET Motor Bicycle Primary cases. We continue to test, and the ownership of the company rides their own product, updating their own bikes, even to the point that, when there have been production changes, we know how the product reacts. We have our ears to the ground, and in the wind, thus we remain in tune with the Product, Owners, and Dealers! This group, the POD, is where we spend our time considering the best interests of all of us. It also contains the most important people in the world to our company.
Ok, on a different subject still related to your questions, my Electra is the steel frame, it is a year or two old, I have not dated it. The alloy bike has 3-piece crank, the steel bike 1 pc. The alloy bike comes with nicer tires, and maybe the wheels are different? My bike has alloy rims, 80 ga SS spokes, and Carlisle type tread pattern on the tires.
I bought mine used from Craigslist for 130 and am tickled silly over the great deal I got!
Mike
