Shiftable Gears

azbill

Active Member
Joined
Dec 15, 2006
Messages
3,697
I believe that you will want the tensioner on the bottom of chain, the engine will pull from top, and shred tensioner quickly, at least, thats what I was told about the tensioner in the bike kit
 


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SlicerDicer

Guest
azkronic said:
I believe that you will want the tensioner on the bottom of chain, the engine will pull from top, and shred tensioner quickly, at least, thats what I was told about the tensioner in the bike kit

It really makes no matter on top/bottom to me. I am just guessing here as I do not have my engine yet.

I do know that the tensioner needs to be on the return leg as there is really no tension on the chain on that side. Not like the driving side of the chain anyway.
 
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Lukass

Guest
The bottom of the chain is the return.

As much as I would love to see this work (48 and a 36 would be sweet you wouldn't need the one in between) I'm pretty convinced it just isn't going to happen.

Have you ever looked at a bike cassette or the ring gears? You will notice they have cut down teeth in some spots and teeth machined on an angle to allow the chain to run off the gear it is currently on. When you actually get a sprocket and chain in your hands you will appreciate how hard it is going to be to get the chain to run off this gear.

Based on the thickness of the chain and the sprockets you will have roughly 15mm between the centreline of the two rear sprockets. I don't know your exact length but I work that out to be roughly 3 degrees deflection from the front sprocket centreline. This is an awful lot for a chain, you can get away with it but it will be noisy as hell and create extra drag.

Have you got enough chain clearance from the frame to fit another sprocket?

You can't run a spring loaded tensioner because the slack side of the chain becomes the loaded side when you pop the clutch to start it.

There is nothing insurmountable there but I think you have your work cut out for you.
 
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custom_tecumseh

Guest
This is how I am planning on shifting gears on my mountain bike.

1774_bike_schematic_1.jpg


I'm probably going to have to remove my pedals becuase i fear i may injure myself if my feet were to come in contact with the crank.

I have sheetmetal to make a guard for that...lol

Comments are welcome, yays and nays.
 
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SlicerDicer

Guest
lol I thought you were going to rip your legs off till I read about the crank. Why not just drive the rear sprocket and use that if your going to remove the pedals?
 
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custom_tecumseh

Guest
Because then I would be limited to only one gear while riding....

doing it this way would enable me to run through my 6 rear gears while already in high gear up front, the 3rd gear.

The centrifugal clutch on my engine should allow me to pedal when the engine is idling...

Atleast thats the plan, lol.

I gotta get a picture of this thing soon...
I'll probably get laughed right out of here, lol.
 
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custom_tecumseh

Guest
I have a 1 piece crank.

So by buying the...

-Freewheel crank adapter
-Cyclone crankset

I'd be well on my way, but...

Aren't these a direct replacement for 3 piece cranks only?
 
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JosephGarcia

Guest
How about using a Jackshaft to transfer engine power to the bicycle drive chain, using the bicycle gears. It would require a chain that not only fits the bicycle pedal drive, but also handle engine torque. It would also require abandoning the pedals as an alternate power source. Maybe keeping them on (but not actually connected to the rear sprockets) to be "legal" They will not notice a small chain missing from that sprocket to the rear.

If this has been mentioned already, it's becuase I'm tired and will read all of your guys posts later, :D in which case this post will be edited.
 

azbill

Active Member
Joined
Dec 15, 2006
Messages
3,697
custom_tecumseh said:
I gotta get a picture of this thing soon...
I'll probably get laughed right out of here, lol.

if you make it and show pics
(even if it doesn't work)
aint nobody here gonna laugh (at least, not too hard) 8)
too many tinkerers and mad scientists :LOL: :LOL: :LOL:
 
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