Has Anyone Moved The 212 Engine's Clutch To The Flywheel Side?

5

5-7HEAVEN

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Right now, I'm almost done with running my 212cc engine's power through the bottom bracket(BB).

Doing so significantly trimmed down the standard shift arrangement.
It eliminated one chain, two sprockets, the jackshaft and its bearings.

It also added safety and more leg space,
due to the absence of the jackshaft under the rider.

However, running engine power through the BB is very complicated.

So I'm thinking of a simpler way to create a shift kit.
Shift kits allow the engine to transmit power through the bicycle's rear gears.

How about installing the clutch on the flywheel side?⚙
 
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Basically, the idea is to connect the engine's crankshaft to the bottom bracket(BB),
on the RIGHT SIDE of the bicycle.

There is just as much power at the flywheel, as there is at the opposite end.

There is no transferring power from the left-side to the right-side of the bicycle.

The fan and fan housing might need to be thrown out or drastically modified.

A custom PTO(power take off) shaft would need to be threaded into the right side of the crank.

Or welded on, if you prefer.

Make the PTO as short as possible, for less radial and axial forces.

Radial forces come from the sprockets' and chain's yanking action.
Axial forces come from the crankshaft's twisting torsional action
onto the pulleys and sprockets.

The longer the crank or axle, the more its mechanical advantage of
twisting and damaging itself or its outer components.

Hey, that's what I'm THINKING, lol.
I might be wrong.:)

Or relocate the clutch to the bottom bracket,
and place a 10-tooth sprocket at the crankshaft.

Then you'd just need a 1" crankshaft stub connection.

Luckily, centrifugal clutches will spin counter or clockwise, so no problem there.

One must be careful with the flywheel's reattachment.
Crank and flywheel have a tapered-bore connection.

The flywheel and CDI will not be touched, modified or need to be adjusted.

So that's it.

I believe the weakest link will be the threaded connection between
the crankshaft stub and the crankshaft.

Thoughts?
 
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While the PTO stub threads onto the crankshaft,
its other purpose is to secure the flywheel to the crank.

So the crankshaft end of the PTO stub would need to be
machined to accept an open-end wrench.

Orrr, the outer end could be machined for a box-end or socket wrench.

And of course, the PTO stub is slotted to accept a key,
to secure the clutch or sprocket..
 
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Of course, the pull start is eliminated in this arrangement.

How in the heck will you start this engine,
WITHOUT A PULL START??

I'm thinking 3 different ways:

1)When you fabricate the PTO shaft,
thread its outer end to accept the OEM flywheel bolt.
Then use a cordless drill to spin-start the engine.

2)The crankshaft on the left side is free!
Slide any sized v-pulley on it.
Groove the pulley's outer edge.
Wrap a rope into the v-pulley and pull-start the engine.

3)Install an electric starter and flywheel.
 
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Whenever you relocate the centrifugal clutch away from the crankshaft,
be very careful which size sprocket you replace it with.

Say you have a 12t clutch on your engine.
You don't have enough space around it,
so you need to relocate it to a jackshaft.
Replacing a 12-tooth clutch with a 12t crank sprocket causes no problems.

When you install a crank sprocket with less or more teeth,
it changes the gear ratio, and your clutch engagement too.

Installing a 10t crank sprocket with your 12t clutch lowers your effective gear ratio(s).
It'd be like swapping your cruising 36t to a winding 43t.....
just by that simple change.

AND THEN.....
at the same time, your clutch which engaged at 1800rpm.....
engages 20% HIGHER!
Since the clutch is spinning SLOWER,
it fully engages at 2160 ENGINE rpm.

Now you sound like a modified moped, lol.

If you put a 12t crank sprocket and a 10t clutch sprocket,
your 1800rpm clutch will engage at 1500rpm.....
and creep you out at idle speed.:(
 
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Chainlube said:
Turn the whole motor around and put a gear on crank and another gear on the bottom of the first gear and now you're running backward compared to the motor. From the second gear run a chain to the BB.

This kind of gear. https://fortnine.ca/en/s-s-cycle-ou...Mxk76tLSfniQZ-rlH9dTPf_j_yi5ye4BoCxkQQAvD_BwE
Click to expand...

The one word that makes everything EXPENSIVE($$$) is.....PROTOTYPE.

The FIRST ONE, the first creation, the first of its kind!

I like your idea, but your way is VERY expensive.
Gears alone are $317 plus shipping.

Don't forget to mention that the gears need to MESH with each other,
not with a chain or a belt.

That's where everything installed needs to be PRECISE, exact and expensive.

No more sliding the sprockets or adding spacers/washers to make adjustments.

If you contract EVERYTHING out, I'd say it'd cost you thousands.

If you've got mad skills and a machine shop, I'm guessing $1K to make a working prototype.

First, you would need a custom main gear or sleeve adaptor made.
Orrr, search the 'net for a PAIR of gears which would work together.

The thick aluminum mounting plate, machining($$$) and secondary gear mounting this protoype needs to be
precise and extremely secure.

Did I mention it'll cost you $$$ to design it, then BUILD this custom HUMUNGOUS($$$) block of billet($$$) aluminum.

Don't forget you'll have to have a custom mounting hub for the secondary gear, with a shaft to support bearings on either side of that secondary gear.

You just know that mounting plate's not gonna line up, and bolt on with common spacers.

It'd take a machinist a LOT of time($$$) to design and fabricate everything.....
and he's not gonna guarantee it'll work!

If it fails, then there's more time($$$) to re-design and re-machine($$$).

Gear lash must be VERY precise, but adjustable.

And YOU!! have to design a way to adjust backlash!


Sooo, from the second gear, you have a chain sprocket bolted onto it.

Of course, you'll need an outer bearing support.

If you don't have that outboard support,
you just KNOW it'll wreak havoc on the primary/secondary backlash.

Now let's talk gear ratios.....
 
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One look at the gears on your link tells me.....

it'll NEVER work.:(

Why?

The rules of physics.

I still remember what I learned in science class 60 years ago.....
small gear/pulley & big gear pulley relationships.

All engines' rpms need to be lowered drastically, especially on bicycles.

To do so, you need a very small gear on the crankshaft,
and a VERY LARGE secondary gear.

That's not why I'm seeing on your link.
 
What about two gears of the same size, maybe timing gears salvaged from the dead car lot. And there's lots of room on that side of the motor to attach a mounting plate for the second gear.
You are right about everything has to be precise.
 
Someone on this forum advised me to strive for 15:1 First gear and 5:1 final drive, with my 212cc engine.

I use a 24t chainring, and my final gear has 14 teeth.
That RAISES the ratio to .5833:1.

So, gearing towards the engine must be 8.57:1,
because 5:1/.5833 = 8.5714.

Using a driven 44t chainring and a 10t reduces gearing to 1.95:1.

So that means you'd need a 20-tooth crank gear, mated to a 39t crank gear.
Or a 25t crank gear meshed to a 49t secondary crank gear.

It's all in the details you forgot to mention.
Chainlube said:
What about two gears of the same size, maybe timing gears salvaged from the dead car lot. And there's lots of room on that side of the motor to attach a mounting plate for the second gear.
You are right about everything has to be precise.
Click to expand...

Two same-sized gears gives you 1:1.

You need 8.57:1 at the bottom bracket.
You could then put a 10t sprocket at the secondary straight-cut gear.....

and an 86-tooth chainring sprocket!
That's almost 14" diameter.

That combination would give you 5.02:1
 
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