after a rear mounted motor that drives wheel by belt and large pulley o the wheel?

[rawly old]

Well, obviously it's winter & no one seems to be out
riding much. Bitter cold here, but not as bad as the mid-west.
However, I am busy fashioning a new shaft with a file. Though
the above set up works fine, I'm planning to swap out the old
friction channel & replace it with my Staton. It will basically be
the same. I just want a more precise shaft & bearing platform.
I also intend to change the plastic tensioner to something with
a better bearing, a skate wheel perhaps. I have boocoo clip ring
bearings. so I may as well put them to use. The result will be only
slightly lighter. What I'm aiming at is long distance durability. This
set up is, if nothing else, very tough. My carpal tunnel's eased up
so back to the file.

P.S. I"ve got a 2" x 36" x 1/8" strap of titanium I thought to split
& use, but the dam stuff is so hard to cut.

 

[darwin]

Hmm what's the scrap value of titanium?

 

[joshua97]

thanks a heap guys but i have decided (at the moment) to try and weld a 44tooth or similar sprocket to a cheap biles steel rim ? hopefully if centered it should be enough to run a chain to the pocket bike motor (mounted on a basic plate 4mm thick bolted to frame and welded to the lower frame where the wheel hub is) then weld a sprocket of some size (i don't know what size atm ) to the pocket bike motor output sprocket (not using a gearbox-using a race bikes direct clutch bell to sprocket for simplicity. as long as i can have the motor adjustable (sideways) and get good chai lineup it should be simple isn - ohh and welding the sprocket to the hub hmm thoughts? thanks again

 

[Loose Nut]

I hope I understand your plan right. I respectfully recommend against welding to the rear hub. With a motor of that power, you need a strong connection, and enough welding to get it done will warp the hub. Also, I just don't think there is enough steel there on most hubs to weld to. If you are sure you need to do it anyway, do you have access to a lathe that you can use as a fixture to make sure the hub is lined up? Very useful for stuff like this.

In you shoes, I would buy rear hub from a Puch Maxi, or Motobecane Moped. Wheels with rusty rims/spokes are available for reasonable prices. Make sure it's one with 36 spokes, most are. Use an online spoke length calculator tool and order 12 gauge or 10 gauge spokes from that online auction site to lace the moped hub to your wheel. These hubs have a bicycle freewheels on the right side, and a big sprocket on the left. They can be swaped out for different tooth counts. Also the hubs have good brakes. Of course going to all that effort, I would make sure I was using a strong rim.

It's your project though, I would like to see pics of how it's going.

 

[joshua97]

hmm i threw out a motobecane wheel shame haha. yea thanks i welded it today and lined up sweet, and got a hot strong weld so i suppose ill just see how it goes ( ill test it on my 70cc pit bike motorised bike first to see how strong it is) cheers, and ill upload pics asap

 

[Loose Nut]

Glad it went well.

 

[joshua97]

thanks

 

[butterbean]

Unless the pocket bike has internal reduction, direct drive from clutch to rear wheel may not work out as well as you think. This is not meant as disrespect, so please don't take it that way. Race bikes go clutch to rear wheel because they have modifications that allow theengine to hit peak rpm's in a very short amount of time. Unless you have experience with these modifications and are an expert tuner, the engine most likely will not reach optimum rpm's for direct drive most of the time. When (if) it does reach peak rpm's, it's either going to climb walls or take off like a raped ape, but you won't get both i.e if it climbs hills well it will have no balls on the flats at all, or it goes like a demon on the flats and you spend a lot of time pedaling whilst staring up at the tops of hills. Unless this engine is already modified to run as direct drive, in which case you will still need expert tuning knowledge to keep it alive. A pocketbike engine running 24 or 26 inch wheels direct drive, I just don't see it working out well. You have to remember that wheel diameter plays a part in gear ratio as well. Not everyone realizes that the wheel is the final pulley/gear and the larger the wheel, the more speed but the less torque. From what I know, pocketbike engines are high revving, so the larger the wheel you're driving, the more reduction is needed to achieve a usable gear ratio. You may end up with a bike that takes a kilometer of pedaling just to get out of its own way. At the very least, find out the max rpm's of your engine and use a gear ratio calculator to plug in different numbers until you come up with the top speed you want and then you will know if direct drive is a possibility or not. There is a sticky somewhere with a link to a good executable ratio calculator, I will find it.

 

[butterbean]

http://jimsitton.net/ratiocalc/ here you go, just download and click run and plug in the numbers you plan to use.

 

[butterbean]

Download the gearratio.exe file