Very satisfied with my first build!

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Pappy

Pappy

New Member
Apr 19, 2009
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Anderson, IN.
If I had a Transmission like this that had a sprocket for a normal chain, I would not need the jackshaft/drivetrain






 
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a_dam

a_dam

New Member
Feb 21, 2009
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Momence, IL
With the setup in the last illustration, you would have a ratio of almost 27:1. That bike could climb a tree! A 6-tooth sprocket on the motor? I didn't know you could get them that small. With the other 3 sprockets (44t, 17t, 62t), and an 8-tooth on the motor, you would have about 20:1, which might still be too much reduction. At 27:1 you will have a very slow top end (about 13mph at 6000 rpm).

Also, in the illustration the 17t sprocket doesn't have much chain contact. It is better to have a drive sprocket at the end so the chain wraps around it as much as possible. The carrier/idler/tension sprocket can go somewhere in the middle between the two ends. Know what I mean?

If built just like the drawing, the 17t would be very likely to skip on the chain.

Looks like you're getting close, though.
 
a_dam

a_dam

New Member
Feb 21, 2009
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Momence, IL
I always think of something else to say after pressing the "post" button.

Like I said, 27:1 is almost certainly too much reduction. I mentioned that changing the motor sprocket from 6t to 8t would give a ratio about 20:1. I picked the motor sprocket just because it would make the most difference with the least amount of change. Two more teeth would barely change the distance between motor and jackshaft. But of course you could change the overall ratio by changing one of the sprockets between jackshaft and wheel instead.
In my opinion, it is better to have more reduction on the first half (motor to jackshaft). That way the chain speed is slower "up front", where your legs and other body parts are, in case a chain breaks. Plus, the jackshaft will rotate slower; easier on j-shaft bearings.
 
Pappy

Pappy

New Member
Apr 19, 2009
214
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Anderson, IN.
The reason for the (carrier sprock) is so that the chain will clear the brake arm, but your rite, the chin could slip or rerail, I'll remove the brake arm's and use a disk brake system that I have, this will do away with the third sprocket. Is there a sprocket that replaces the 6T sprocket on the clutch? the chain and two sprockets on the left side of the bike are mini toothed, meaning that the chain is only about 3/8 thin, half the size of a standard chain. If I can find such a sprocket, say a 12T or 15T then I can do away with the jackshaft altogether and have 12 to 44 or 15 to 44 what ratio would that give me?


Scott
 
NEAT TIMES

NEAT TIMES

New Member
May 28, 2008
1,964
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PENSACOLA, FL
Pappy, Thats A Great Drawing. Did You Change All Those Gears Already? You Will Have A Good Machine When The Sprockets Are Right. You Will Need The Jack Shaft. The China Girl Motors Already Have A 4.2:1 Ratio In The Engine, Thats Why They Don`t Need A Jack Shaft. The Reason I Recomended The 63 Tooth On The Rear Axle, So You Would Need To Get Only I Sprocket. I Did Not Take Account Of Your Smaller Rear Wheel. I See Now That You Have The Chopper Rear Wheel (20" X 4" Wide?). It Looks Like You Have 1/2" Pitch Bicycle Chain On The Rear, Thats Fine. I Have 3 Schwinn O C Choppers, I Will Measure The Rear Tire Tomorrow(chopper) They May Close Enough To 26" With That Fat 4" Tire. What Sprockets Do You Have On The Bike Now? I Will Look At Your Last Blue Print Again. I Had The Members Mixed Up, A-dam Got The 200 Mpg.. So Many Members, It Gets Confusing.
 
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NEAT TIMES

NEAT TIMES

New Member
May 28, 2008
1,964
1
0
PENSACOLA, FL
If You Want To Give It A Try, Make The Front 8 Tooth On Engine To The 62 Tooth You Have On There. Then The 17 To The 36 And You Will Be Real Close (16.4 To 1). That Should Be Fine With The Smaller Wheel. You Can Try It With The 6 Tooth On The Engine, It Won`t Hurt Anything.
 
a_dam

a_dam

New Member
Feb 21, 2009
351
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0
Momence, IL
I see now that you already have 6t and 62t mini-toothed sprockets. That's fine. Use what you got. Also, if you already have a 44t on the wheel, that's fine too. Then you can adjust your gearing with the small j-shaft sprocket. I think 17t will be too small. I'd try about a 25t. That'll give you 18:1 which should be in the ballpark. Gearing is a personal thing depending on riding style, terrain, etc.


Oops... I posted too late, Neat Times! It's like dueling banjos!
 
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