new bike idea

Toby woodman

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does anyone have any advice or past experience on something like this. I was thinking I was thinking to use a 2 inch v belt pulley, coming off a honda gx160. This will go to a jackshaft, with a 6 inch belt pulley input, and a 10 tooth sproket going to a 44 tooth on the rear wheel. I will start by using a bike rear wheel with a disc brake mounted sproket, but will move to heavier duty aluminium rims if the original project works well. The v belt will be tensioned by a foot mounted tensioner, to give the feel of a manual clutch. if the project works well, I will probally buy a smaller and lighter engine like a 79cc, for less weight and stress on the wheels and drivetrain. and move to better wheels, does anyone have any experience of homemade bikes like this. I'm only 16, so this project will probally be built with old mower v belt pulleys, and junk bikes as a proof of concept. Advice would be appreciated.
 
(6/2)(44/10) gets you a combined 13.2 reduction ratio
Official specs from honda.
Capture+_2024-04-07-13-46-31.png


Using this site, (https://www.omnicalculator.com/everyday-life/rpm)
and assuming a 26 inch wheel you get a top speed of 21.2mph(33.5.kmh) and a stupid amount of torque. Climb a dirt wall with that. 10nm multiplied by the reduction ratio then divided by the radius of a 26 inch wheel gets you 97 and change foot lbs right at idle.
gx160powercurve495x630px_2.jpg


Regarding the actual construction of such a bike: you are going to need to start with strong frame, and gusset up the joints just to handle the torque. Not to mention the sheer mass of that engine. 15 kilos! Engine weighs more than the many decent bikes!

The big question is really this, what do you want? And what do you have to work with in terms of parts, tools and materials? Something assistive? A chopper?
 
ive got a welder and a massive stockpile of steel and loads of old bikes i've piked up off facebook market place for free. I had that engine mounted on a diamondback frame in the summer and im not concerned with the legality because im 16 so all types of motorized bike are illegal. The frame held up well but this is just a proof of concept because the honda gx160 is what I have. If the belt drive works, and i will also try a direct 1.5 inch pulley to a 26inch homemade belt sheave drive system. I will buy a lifan 152 which is about 2.5 hp. Im looking for something reliable and good with the steep hills around me. I went with belts because chains make a noise and require more miantainance. the belt also allows me to get rid of the centrifugal chain clutch, because good go kart clutches are expensive, and cheap chineese ones are just a waste of time. I put some pictures below.
 
pictures
 

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Go for it, Toby. By the time you're 18 you'll be a master builder! Meantime, keep in mind that bicycles aren't built to handle horsepower, just puny human power. Any time you tie massive power to weak mechanical components something is going to come apart. You don't need a lot of horsepower to get you down the road. Finesse outperforms brute force every singe time. Use smart design and gearing to get you up to speed instead of brute force. Just look at all the 50cc bikes around the world that will go 60K or more.
 
Go predator 212 or 224 & a 30 series torque convertor. That should pull up any hill it encounters. Plus it would be alot easier to design & build.
 
Go for it, Toby. By the time you're 18 you'll be a master builder! Meantime, keep in mind that bicycles aren't built to handle horsepower, just puny human power. Any time you tie massive power to weak mechanical components something is going to come apart. You don't need a lot of horsepower to get you down the road. Finesse outperforms brute force every singe time. Use smart design and gearing to get you up to speed instead of brute force. Just look at all the 50cc bikes around the world that will go 60K or more.
Well put. The only thing about brute force is it can make things alot funner. When the front wheel can pull off the ground it can be really fun. Plus the first time you flip it backwards you'll learb to be alot more careful lol.
 
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