best way to gear motor to wheel

[spad4me]

I don't think a 5:1 transmission will bolt onto his chainsaw engine.

I could have sworn he said his engine was similar to Detonators gp 460.
To clarify The transmission uses a 76 mm auto clutch found on most rc and pocketbike engines.
I could have easily misunderstood though.

 

[michaelr123]

wow i havent kept up with this, new gear ratios: 8-72 tooth, 9-28 tooth, or pretty close to that so im shooting for like a 1:25 ratio for first gear is that good enough with a little push?

also, for clutch im just going to modify an 8 tooth sprocket to the clutch bell and run it to a 72 tooth gear, and thats in a drive train with a 9 tooth gear to my back gear cassette, i'll be modifying that later, but for now its going to stay as it is,

and ya i know the chainsaws loud, but im going to make a muffler and install that,

im going to be using two different chains actually, one was off my bike and i have some from my garage door that broke hopefully that works with an 8 tooth sprocket off it, if i can make that work, that'll save me like 25$ also bike was free, chainsaw free, only thing i've bought so far is bolts and a drill and tap set, and 10$ bucks that some bike shop ****** ripped me off for just taking my crank arms off...

 

[michaelr123]

hey quick question, my rear gear shifter like literally fell apart in front of me from the handle twist control to cable connection, should i just take it to a bike shop and have them repair it?? i mean the twist control is like completely shot, broken, and far beyond hope.

 

[5-7HEAVEN]

Up to you. I've always used click shifters. You could just take the bike to the shop and have them install and adjust the cable and derailleur.

 

[5-7HEAVEN]

wow i havent kept up with this, new gear ratios: 8-72 tooth, 9-28 tooth, or pretty close to that so im shooting for like a 1:25 ratio for first gear is that good enough with a little push?

also, for clutch im just going to modify an 8 tooth sprocket to the clutch bell and run it to a 72 tooth gear, and thats in a drive train with a 9 tooth gear to my back gear cassette, i'll be modifying that later, but for now its going to stay as it is,

and ya i know the chainsaws loud, but im going to make a muffler and install that,

im going to be using two different chains actually, one was off my bike and i have some from my garage door that broke hopefully that works with an 8 tooth sprocket off it, if i can make that work, that'll save me like 25$ also bike was free, chainsaw free, only thing i've bought so far is bolts and a drill and tap set, and 10$ bucks that some bike shop ****** ripped me off for just taking my crank arms off...

I hope you mean 25:1 gear ratio. For a single-speed system, that's be a good start.

If you intend to run through a shift kit, shoot for 40:1 first gear or higher. Chainsaw motors are high-winding. At 40:1, your bike will leap off the standing start and be great at the bottom of a steep ramp or hill. At 25:1, your bike might need pedal-assist for a good start and need lots of help at the ramp or hill.

I run 28.64:1 at the chain ring sprocket. By the time it reaches the derailleur, firdt gear is at 32.36:1. I am gearing even lower to 36.75:1 for better acceleration.

Without using the 5:1 pocket bike gearbox, you will prolly need TWO sets of jackshafts to formulate a low gear. An 8/72 combination matched with a 10t/32t sprockets = 28.81 at the chain ring. Multiply that with a 30t/34t bike sprocket to get 32.54:1 in first gear and 16.27:1 in 8th gear w/15t sprocket.

 

[DougC]

.... one of my biggest needs is WHERE DO YOU BUY GEARS???? i've looked all over and only found a few spotty places that sell a few gears, can anyone offer a suggestion as to were i can find spur gears for a drive train?

It would help to fill in your location info. You could be anywhere in the world, and everything isn't available anywhere.




For a bicycle drive, what you would want to use is the 16- or 12-diametrical-pitch hardened steel gears, with a 20- or 25-degree pressure angle. Helical-cut gears would be the quietest, but they would cost 2X what straight-cut gears would.



In the USA, McMaster-Carr sells some 16- and 12-dp steel straight-cut 20-degree spur gears, but they are not hardened (if you had access to an oxy-acetylene torch you could try to flame-harden them yourself). Even at that, they are fairly expensive. The plain-bore ones are cheapest and most-versatile but you need to be able to machine the bores and cut keyways into them to use them.

Stock Drive Products (also USA) sells hardened steel gears, but they are miniature--the largest diametrical pitch they offer is 24, which is too small for a bicycle drive. And despite the small sizes, the prices are still pretty surprising.



If you desire to make your own mix-and-match reduction gearing, the easiest way is to use roller chain (yes bicycle chain) and make your own sprockets in any size you want, from flat sheet steel. It can be done passably well with just a drill press and an angle grinder.

You still need a way to mate & key your home-made sprockets to a shaft, but you can make a klunky shaft fitting with just a hacksaw and drill press too. The one problem you *might* have is that you need to be able to bore a hole that is the same diameter as the shafts you are using. Most common home-size floor drill presses top out at 1/2-inch, which might work but is a bit thin IMO unless you use hardened-steel shafting. (McMaster does sell 1/2" dia hardened steel keyed shafting, btw)

Also,,, all this above assumes that the largest single gear reduction you have is the last one, between the reduction case and the rear wheel.




Unfortunately, the cost of producing steel gears means that there is very few places that produce mix-and-match sizes.

If you like building small mechanical stuff, Stock Drive Products has a LOT of cool parts--but they're all way too small for even a bicycle drive.

 

[5-7HEAVEN]

Welcome to the world of the pocket bike's drivetrain.

All gears, sprockets, freewheels, chains and transmissions are there to be retrofitted onto the bicycle. Combined with the lowest possible gears, a ratio of 56.5:1 first gear is available. All of this at dirt cheap prices, which is less than $100.

Since the chainsaw engine will not bolt onto the 5:1 gearbox, maybe a go-kart tranny would work.

Another issue to resolve is attaching a centrifugal clutch in the system. A Comet clutch might work on the jackshaft.