Cannonballs Abbynormal 3Speed.

[KCvale]

When factoring gear ratios the formula is in teeth.

The Primary is what is being driven by the engine, the secondary is what is being driven which in turn will become the primary in the next stage.

(Secondary/Primary sprocket teeth) x (Secondary/Primary) x (Secondary/Primary) all the way down the line to final ratio at the wheel on the road.

A reduction is a whole number, an increase is a decimal fraction number.
The farther you go down the line the less a difference you can make.
This iswhy you shoot for the closest ideal gear ratio as close to the source as possible, and then fine tune with final drive ratio on wheel.

A 2-stroke does a 4.1:1 gear reduction right at the clutch so all rpm calculations start with 4.1 as the primary.

4-strokes have no initial reduction, hence why they have a transfer case.
4-5:1 is typical.

Regardless of the engine type, or what is in front of it, just follow the math of reduction in direct relation to how many RPM's the engine is turning.

This is a handy tool to enter 3 of 4 variables to determine how fast you can, what reduction you need, tire size or RPM to go based on drive RPM, Tire size, speed or gearing differential.
http://www.advanced-ev.com/Calculators/TireSize/

Just for a simple stock direct drive 2-stroke with a 10T primary and 48T wheel mount final drive sprocket the formula is:

4.1 x ((48 {rear sprocket teeth} / 10 {engine drive sprocket} ) = 4.8)) = 19.68 reduction.

Just click the value you want computed.

For example I just filled in tire size as 26", speed at 40MPH, and differential of 19.68 and click compute RPM.
Just over 10K actual engine RPM for that gearing.

Drop the rear sprocket by 4 teeth to a 44T and the ratio changes.
4.1 X 44/10= and 18.04 ratio.
You can drive that speed at 9325 RPM.

Or, with the above 18 gear ratio and 9.3K RPM what size tire would I need to drive 45 MPH?
I just clicked compute tire size.
29.3 " wheel because you wheel is the last 'gear' in the equation ;-}

That should help you guys come with the right combinations you want, it sure helped my on my 4-stroke long shaft shifter project, I have a 22.2 ratio to start with ;-}

 

[KCvale]

I'm wondering how it would go driving the hub with a belt and pulley instead of a chain.

Something like this ;-}

CB2 has neat new option to make a direct drive at least a 2 speed, I just like using the parts as intended and get all the gears is all.

 

[Intrepid Wheelwoman]

Yes very much like that KC

 

[curtisfox]

Would a Schwinn approved austria 3 speed hub with oil cap be any good for this?.........Curt

 

[bowljoman]

I used one for a friction drive. It tried to sling all the oil out. I glued a 2 1/4 inch ID radiator hose over it in my initial search for friction drives. It worked, ran dry, bt I continued to glue on new hose chunks for a while.

Finally I got tired of disassembly that I just went with metal hub to tire.

after a hiatus of a few years, I brought it back out nad it worked as before but with an ever-widening neutral between 2nd and 3rd I think.

I would think it to work fine if one put a zirk on the oiler.

 

[cannonball2]

You can fill most anything that uses oil with 00 grease. Its a semi runny grease. Will stay in most things like gear cases even with bad seals that oil will leak from That said don't know how it will do in something subject to centrifugal force but bet it would do ok.

The bike is down now waiting on new tires, a clamp on style hub mount and 32t sprocket. Probably going to have an issue with that as finding a 32t that's decent to run a BMX chain has been a problem. The sprocket coming is for a 415 chain and there is probably no clearance since I designed the system around a BMX chain. Will have to see. May mean a machine shop visit to have the sprocket turned down.

 

[curtisfox]

Kool good to now, the hub is on a compleat Schwinn bike so will have to see what come later down the creek.................Curt

 

[cannonball2]

How To Avoid A Trip To The Machine Shop:

So I designed this build around BMX chains because I like them and they are compact. I dont like 415 chains they are always too loose on the sprockets side to side and that would crash with the other chain. So BMX it is. There WERE sprockets available but not now(at least any decent ones) So lets make one work. I had a tapered grinding stone that centered the sprocket perfectly. I clamped it in place and chucked it into my drill set at a very low speed. I then just proceed to reduce the thickness with my side grinder while the drill turned it. Didn't take long and its perfectly uniform. Looks crude but worked like a charm! Now fits the BMX chain. Next I carefully centered, drilled and counter sunk the sprocket to fit the clam shell adapter. About 45minutes of careful work and no$$ spent. I certainly don't mind paying the local boys for their fine machine work, but Im just as happy not too.
The small sprocket is a 32T which is what I wanted, the adapter came with a 36 which made a fine template.

 

[cannonball2]

So its finally finished(until the next thing happens). Sprocket worked out perfectly. The junk sprocket that came with the rag joint was improperly stamped causing all sorts of problems. Was blaming the rag joint for being impossible to get right. I have a rag joint/sprocket on the test mule bike, it has never given a problem. I know the clam shell is the way to go, just didn't want to spend the $$ until I saw whether this thing was gonna fly or not. Don't mind dropping a little $$ now

Anyway the bike is really cool with the 32t gearing. The engine has very little time on it so am not running it real hard. Still its fun to run through the gears. First will hit 18, second 26 and 35 in third is as high as I have taken it. Its very relaxed at 30. I believe when its broken in 40 is not out of the question. The ratio is actually overdriven a bit as the final drive sprocket on the hub has 23t vs. the 22 on the primary side, so the actual gearing is more like a 31t maybe?. I accidentally started the thing in second to no harm. The IGH is cool you can gear it down if you want, or just come to a stop and put it in first.
Now to get some time on it. Could last 10mi or 10years, hopping for the latter.

Heres the latest pics with the new tires, the modded CG sprocket and the reason to run the BMX chains. 415 can be used but it needs to be built that way.

 

[silverbear]

Congratulations! That is so clean and nice... must feel really good knowing that you did it. It works! Woohoo!
SB

 

[LandSpeedRecord]

Very nice Cannonball! When I re install my motor tomorrow I am going to look closely if this is a possibility on my bike. Really curious how this is going to hold up. I bet it will last a long time with a normal CG and not too much abuse. I find pavement cracks and rough roads seem to put quite a it of shock into the drive line. Let us know if there seems to be additional drive line lash with the set up. I would think the BMX chains are an especially good idea as they might be slightly weaker than the hub, depending the chain. I know some of them are stronger than standard 415 chains it just depends on which one. I really want to convert to them also and will probably do so with my next rear sprocket change. Happy motoring, and great work!!

 

[KCvale]

Well done.

I like 410 HD Z 'BMX' single speed chain too.
415 and especially 41 chain have always seemed like yacht anchor chain on a dingy to me but that is neither here nor there.

All the SBP jackshaft use it and that isn't what gives with a failure unless it's one your glad the chain broke and not your frame or wheel.

Another really good strong single speed chain is Z HS 710 1/2 link chain.
Expensive but darn strong and friendly to work with, every link is a 1/2 link so sizing is really easy.

Test time...
Like you mentioned, it may only make it around the block, but it may make it all the way around the world.
I hope for the latter for you ;-}

 

[Intrepid Wheelwoman]

So its finally finished(until the next thing happens). Sprocket worked out perfectly. The junk sprocket that came with the rag joint was improperly stamped causing all sorts of problems. Was blaming the rag joint for being impossible to get right. I have a rag joint/sprocket on the test mule bike, it has never given a problem. I know the clam shell is the way to go, just didn't want to spend the $$ until I saw whether this thing was gonna fly or not. Don't mind dropping a little $$ now

Anyway the bike is really cool with the 32t gearing. The engine has very little time on it so am not running it real hard. Still its fun to run through the gears. First will hit 18, second 26 and 35 in third is as high as I have taken it. Its very relaxed at 30. I believe when its broken in 40 is not out of the question. The ratio is actually overdriven a bit as the final drive sprocket on the hub has 23t vs. the 22 on the primary side, so the actual gearing is more like a 31t maybe?. I accidentally started the thing in second to no harm. The IGH is cool you can gear it down if you want, or just come to a stop and put it in first.
Now to get some time on it. Could last 10mi or 10years, hopping for the latter.

Heres the latest pics with the new tires, the modded CG sprocket and the reason to run the BMX chains. 415 can be used but it needs to be built that way.

Wonderful, congratulations, you did it CB

 

[cannonball2]

Thanks for all the kind words and compliments everyone! This wasn't a difficult build especially for a first. The only parts fabbed were the hub mount and the secondary sprocket(actually just modded). The hub seems strong enough. We will soon know as I plan to keep the bike on the road to find out.
If anyone needs more info on the conversion I will be happy to list out the parts used.

Now to add the reversed 3speed to the other bike to see how it works out. Cool thing is if either hub fails just remove the hub, mount and its chain, install a chain from the engine to the wheel and ride on.

 

[bowljoman]

Yay!!!

Sounds like its dialed in proper.

 

[bowljoman]

I expect you'll get thousands of miles if its built as tough as a nexus inter-3 tricycle hub I use. And I expect any modern hub to be capable when you remove the spokes and spin it up to 1000 rpm.

 

[bowljoman]

My original prototype back in 1993 used a 1970's SA 3 speed hub as a friction drive and would hit 30 mph using a large bore 4 stroke. I filed the spoke flanges off and used the IGH as a friction drive. Careful not to grind through the shell to the pressed in cariers or it will leak. I must have spent hours grinding down more than a couple .

 

[bowljoman]

About three years ago, I went to a used bike shop and looked for some IGHs.

I **** my pants when I saw one of the hubs I ground the spoke flang off of. I told them the back story and they gave it to me free.

 

[KCvale]

About three years ago, I went to a used bike shop and looked for some IGHs.

I **** my pants when I saw one of the hubs I ground the spoke flang off of. I told them the back story and they gave it to me free.

Hehhe, cool.
I like free, I like trading in new parts on a new bike I don't need for things I do at the bike shop to begin with.

That's a hard gig to pull off unless you have a friendly small local independent bike shop you do lots of business with.

According to my receipts I did near 5 figures with them last year and that doesn't count the customers that went up and bought the bike of choice for me to motorize.

 

[cannonball2]

KC I have been eyeing the 1/2 link chains, might just go for one. Invariably you wind up with one chain just a smidge too loose.

Bowljoman, sounds like you have been on this IGH thing for a couple of decades, you should know. The FD thing gives me inspiration to add one to my old Maytag powered FD. Hasn't got enough power to pull the skin off a rice pudding so to speak, so the hub should last forever.