# Building a 4-stroke bicycle

J?

Gentlemen. Can someone post the formula for the drive/sprockets for calculating the mph, and torque?
The smaller the total reduction the less torque you'll have; the larger the total reduction the more torque you'll have. A simple formula for torque is to look on your engine specs for max torque then it's this formula.

Max engine input torque × Total Reduction = total drive system output torque.

You could do this if you can't figure out how to calculate total reduction to determine torque

(Max engine input torque x belt transmission reduction × wheel sprocket)÷(transmission drive sprocket)= total drive system output torque.

For speed:
(engine max hp rpm × wheel diameter × π × transmission drive sprocket)÷(1056 × belt-drive transmission reduction × wheel sprocket) = mph.

I use this.https://www.omnicalculator.com/everyday-life/rpm

You need to keep this in mind you're a large person so that means you're putting a larger load demand on your engine. A certain hp/torque rating is only going to generate a certain max speed on level ground for a certain weight.

Another way to look at it, think of hp as a set amount of pressure and torque as the length of a lever. The shorter the lever on the fulcrum the less weight the pressure can lift. The longer the lever the more weight the pressure can lift. If you have the same weight that both levers can lift comfortably with the same pressure. Then the shorter lever will lift the weight more times in a given time period due to it having less travel distance during the lift.

It's all about balancing the work load between hp and torque. The hp is fixed but output torque can be varied. This statement is even more so true for a single ratio drive system. With my shifter bike I have a total of 9 drive ratios to select from. Which is why I can ride by Darwin pushing his larger engine bike up a really steep hill. Though he'll pass me when he gets back on level ground. At the end of the day, I won't be as tired if we're riding in steep hill 🏞 country.

Here are the formulas. Probably easier to use a table like CloakedV posted

Speed in MPH.

(RPM × Wheel Diameter × π)÷(1056 × Total Reduction) = MPH

Total Reduction

(RPM × Wheel Diameter × π)÷(1056 × MPH) = Total Reduction.

There is this one too.

This one is easy . If you are not using a jackshaft enter 10 in the JS Input and JS Output boxes.

Guys. My used bike I got from my brother is turning into a pain.

I was thinking. If I mounted the engine on the back of the bike. How does that work?

Does the motor still perform as well as if it were inline with the chain?

Has anyone tried this?

Edit: I went and read @Sidewinder Jerry older post.

Am I able to mount my 53cc skyhawk engine this way? Or no.

Guys. My used bike I got from my brother is turning into a pain.

I was thinking. If I mounted the engine on the back of the bike. How does that work?

Does the motor still perform as well as if it were inline with the chain?

Has anyone tried this?

Edit: I went and read @Sidewinder Jerry older post.

Am I able to mount my 53cc skyhawk engine this way? Or no.
Lots of people in the past have done rear rack mounts. If you go to some of the very first forum photos you'll find most of the bikes were rear rack builds. My rear rack build gearbox is designed for this type of mount. The Staton Inc gearbox is the strongest and highest reduction transmission currently on the market for motorized bicycles.

Guys while trying to adjust the protective cover on my 4g transmission I noticed this in the 20T gear.

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