Bike transmission and sprockets

[Thedude]

Do you think the sprockets on a bike will work for a go kart? Also what do you think about using the gear shift thing from the bike?

 

[Kaptain Krunch]

Nope, Even if the chain didnt just break, it would throw chains and wear out sprockets like crazy.

If you want a transmission get a motorcycle/atv engine.

 

[motor_head]

you mean a bicycle bike
maybe if you building a pedal kart, even a 3hp would wear it out pretty quick

 

[Kenny_McCormic]

Maybe with a little 50cc motor w/ cent clutch. That should be fairly soft on the trans. Just don't shift it under power.

 

[Thedude]

My plan was to use a centrifugal clutch to drive it so it wouldn't move at idle. Then I would shift into 1st drive until I want to shift to 2nd. Then I would release the gas, slowing down the tranny, shifting then putting the gas back on. Does anyone have any other ideas that are cheap?

 

[Sam W]

NOPE. lol tried it on my first cart

 

[Doc Sprocket]

What transmission are you referring to- The rear derailleur system from a bicycle? I don't think it's up to the task either. Maybe if you used a weedeater engine (25cc), but the gear ratios wouldn't be appropriate.

 

[dpaxson]

also, just because you let off the gas on an engine with a centrifugal clutch it won't disengage. the clutch will remain engaged until the kart has coasted down to a speed where the back wheels are spinning the engine below the engagement rpm

 

[motor_head]

you could build a light weight cart with a chainsaw motor to just drive around in and save gas

to shift bike gears just let off the gas so the hub freewheels then shift, it has to spin or it doesn't shift

 

[t0x1k]

also, just because you let off the gas on an engine with a centrifugal clutch it won't disengage. the clutch will remain engaged until the kart has coasted down to a speed where the back wheels are spinning the engine below the engagement rpm

What? no, the weights in a clutch are only operated by the engine by centrifugal force. Once the throttle is release the weights are retracted and the engine is free spinning.

 

[Russ2251]

dpaxson is 100% correct.
Shoes will not disengage until minimum lock-up rpm is realized.
Generally between 1800 to 2200 rpm, more or less according to model and is easily proved out.

 

[t0x1k]

That doesn't make any sense. I've had my original cart in the air with a hillard clutch and the shoes retracted after letting off the gas and the tires were still spinning. Same goes for a CVT, releasing the throttle disengages the clutch and the kart freewheels.
If that was the case and it didn't disengage until the kart was coasting at minimum engagement speed you would engine brake from the kart trying to over come the engine compression. Just like a car or truck with the shifter in 1st gear, the engine and transmission are locked together and RPMS never drop and you slow down like you're towing a building.
Unless you're talking about the time from releasing the throttle to idle rpms, which shouldn't be more than a couple seconds.

I'm confused now.

 

[lude]

That doesn't make any sense. I've had my original cart in the air with a hillard clutch and the shoes retracted after letting off the gas and the tires were still spinning. Same goes for a CVT, releasing the throttle disengages the clutch and the kart freewheels.
If that was the case and it didn't disengage until the kart was coasting at minimum engagement speed you would engine brake from the kart trying to over come the engine compression. Just like a car or truck with the shifter in 1st gear, the engine and transmission are locked together and RPMS never drop and you slow down like you're towing a building.
Unless you're talking about the time from releasing the throttle to idle rpms, which shouldn't be more than a couple seconds.

I'm confused now.

i agree with you dude, in my cart when i let off the gas wile still going my engine is at idol and therefore not engaged to the rear end.

 

[Doc Sprocket]

Unless you're talking about the time from releasing the throttle to idle rpms, which shouldn't be more than a couple seconds.

Maybe even only one second. An eternity when you're trying to grab a gear! It's all academic anyhow...

1) The driver actually HAS to move to accomplish a successful shift using a bike derailleur system. Ever try to shift a bicycle without pedalling?
2) These bike components are going to detonate anyhow. How many horsepower are YOU?

 

[Kaptain Krunch]

Basically you could not shift fast, rather than


brrrrrrrmmmm--brrrrrrrrrrmmmmmmmmmm
It would be
Brrrrrrrmmmm---------------------brrrrrrrrrrrrrrrrrrrrrmmmmmmmmm

The slower you shifter, the slower you will be moving by the time you get back on the gas, and as im sure you know, 5mph in second doesn't always work out so well.

Of course thats all theoretical anyhow, since it would not work. Your would break/wear through chains and sprockets like crazy.

 

[t0x1k]

Maybe even only one second. An eternity when you're trying to grab a gear! It's all academic anyhow...

1) The driver actually HAS to move to accomplish a successful shift using a bike derailleur system. Ever try to shift a bicycle without pedalling?
2) These bike components are going to detonate anyhow. How many horsepower are YOU?

Thats because there is a one way bearing in the rear to allow coasting without the pedals moving.

This could be achieved properly, but not easily or cheaply.
You would need a custom derailleur that moves farther left and right with each gear change, the sprockets would need to be custom, ever look at a multi speed bike sprocket? the teeth are beveled for a reason. It would have to be #35 or #219 chain. You would also need a guide between sprockets or else it would get jammed between gears. Jamming gears at 30 mph wouldn't be pretty. Plus a heavy duty chain tensioner. It probably wouldn't work without a one way bearing system on the rear axle. Have you ever pedaled as fast as you can and shifted gears, things normally go bad.
After all is said and done, you could probably have bought a bike engine and transmission.

 

[Russ2251]

As a test to see when centrifugal clutch disengages, get to your max speed and kill the engine. Engine will not stop immediately but will drag kart speed down fairly quickly until clutch completely disengages, at which time kart will then freewheel.

 

[BriggsTwins]

as far as i know, the clutch will remain engaged if the wheels and the motion of the kart are spinning it fast enough, just because the engine wants to slow down, doesnt mean the clutch wil release. if the kart makes it spin at the right speed (assuming its engaged) it will stay that way until it reached the disengage point. as for bike gears, they are not a good idea, not to bash on ya but the effort would be better spent on something better. youll be much happier with the result

 

[dpaxson]

if your clutch was really old and slipped it could disengage earlier but that shouldn't happen.

 

[Linksep]

I think a derailleur setup could be made to work, it might not work well, and I doubt it would last as long as a CVT or conventional single speed setup.

Now maybe a 3-speed hub system could be figured out?