Chainlube
Well-Known Member
Now, about about making a gearbox for the two gears off the motor, basically running 1-1. Then have shaft from the second gear come through the gearbox and attach a TAV that has a chain going to the chainring.
Has Anyone Moved The 212 Engine's Clutch To The Flywheel Side?
- Thread starter 5-7HEAVEN
- Start date
5-7HEAVEN
Well-Known Member
I've run into a MAJOR stumbling block.
It's NOT about fabricating and scrounging/resourcing parts never made for this purpose.
It's about gear ratios.
Moving the clutch to the spindle eliminates the much-needed mathematical relationship.
It deprives the bicycle of a necessary multiplying factor.
For example, a 10t clutch and a 20t sprocket = 2:1.
A 34t chainring and a 10t sprocket = 3.4:1
2 x 3.4 = 6.8
That's 6.8:1, which is GREAT for a 212cc engine.
Move the clutch to the jackshaft, eliminating the 2:1 reduction.
Now you have 3.4:1.
Your bike literally goes nowhere on engine power,
and your clutch burns up.
That's a gigantic number in lowering/raising gear ratios.
It's NOT about fabricating and scrounging/resourcing parts never made for this purpose.
It's about gear ratios.
Moving the clutch to the spindle eliminates the much-needed mathematical relationship.
It deprives the bicycle of a necessary multiplying factor.
For example, a 10t clutch and a 20t sprocket = 2:1.
A 34t chainring and a 10t sprocket = 3.4:1
2 x 3.4 = 6.8
That's 6.8:1, which is GREAT for a 212cc engine.
Move the clutch to the jackshaft, eliminating the 2:1 reduction.
Now you have 3.4:1.
Your bike literally goes nowhere on engine power,
and your clutch burns up.
That's a gigantic number in lowering/raising gear ratios.
5-7HEAVEN
Well-Known Member
Now I realize that multi-speed hub needs to be internal, not cassette-type.
Why?
Because the biggest commonly-used cassette gear has 34 teeth.
A 24t sprocket is the smallest that'll bolt onto a freewheel.
That's 34/24 = 1.42:1
An 8-speed Sturmey-Archer internal gear hub(IGH) has a 3.25:1 First gear.
Multiply its 25t sprocket with a 24t chainring = 1.041 = 3.385:1
Since the engine-to-clutch is 1:1, there's no extra gearing.
3.385 x 1 = 3.385:1
The clutch will self-destruct, and
THAT'S in First gear!
Not in Eighth gear, but First gear!
Even with a low 3.25:1 First gear
Back to the drawing board.
Why?
Because the biggest commonly-used cassette gear has 34 teeth.
A 24t sprocket is the smallest that'll bolt onto a freewheel.
That's 34/24 = 1.42:1
An 8-speed Sturmey-Archer internal gear hub(IGH) has a 3.25:1 First gear.
Multiply its 25t sprocket with a 24t chainring = 1.041 = 3.385:1
Since the engine-to-clutch is 1:1, there's no extra gearing.
3.385 x 1 = 3.385:1
The clutch will self-destruct, and
THAT'S in First gear!
Not in Eighth gear, but First gear!
Even with a low 3.25:1 First gear
Back to the drawing board.
5-7HEAVEN
Well-Known Member
It'd be MUCH easier if I eliminated the pedals.
Then I could use an NINE-TOOTHED sprocket on the BB.....
and a 45t rear wheel sprocket.
That'd give me 5:1 in Eighth gear, and
and 15.75:1 in First gear.
I'm guessing this 7"(45t) sprocket could be attached to the 25t IGH sprocket.
But where's the challenge, if I don't have pedals, lol?
Then I could use an NINE-TOOTHED sprocket on the BB.....
and a 45t rear wheel sprocket.
That'd give me 5:1 in Eighth gear, and
and 15.75:1 in First gear.
I'm guessing this 7"(45t) sprocket could be attached to the 25t IGH sprocket.
But where's the challenge, if I don't have pedals, lol?
Last edited:
Chainlube
Well-Known Member
Ya, you want to make a bicycle, not a motorcycle.It'd be MUCH easier if I eliminated the pedals.
Then I could use an NINE-TOOTHED sprocket on the BB.....
and a 45t rear wheel sprocket.
That'd give me 5:1 in Eighth gear, and
and 15.75:1 in First gear.
I guess this 7"(45t) sprocket could be attached to the 25t IGH sprocket.
But where's the challenge, if I don't have pedals, lol?
5-7HEAVEN
Well-Known Member
I'm giving this one up.....
because I've got ANOTHER wild idea, lol!!
So much Covid-19 time on my hands.
because I've got ANOTHER wild idea, lol!!
So much Covid-19 time on my hands.
Chainlube
Well-Known Member
Well, if you finish it off as a regular shift kit, your bike is still going to be fast and probably not burn up any bearings.
Chainlube
Well-Known Member
Then on to wilder ideas!
5-7HEAVEN
Well-Known Member
Yahoo!
5-7HEAVEN
Well-Known Member
Well, this idea still lives.
The gearing ratio issues can been resolved. by using an internal gear hub(IGH) on the rear wheel.
Ratios range from 1.00 to 3.25:1.
With a 12t clutch, a 48t and 24t chainring and a 25t rear sprockets, gearing ranges from 4.17 to 13.54:1.
Or a 120t timing pulley and a 23t pulley clutch, a 27t chainring and a 25t rear sprocket results in 4.83 to 15.7:1
Perfect in both cases.
A #41 48t chainring sprocket on the right side of the BB is drilled to bolt to an SBP freewheel,
which screws onto the SBP crank arm.
410 A 48 Tooth for 5 hole Flange type freewheel (staton-inc.com)
Front Freewheel - Heavy Duty - Sick Bike Parts
Front Freewheel - Heavy Duty - Sick Bike Parts
The inboard 24t chainring is 1/2 x 1/8 and uses a BMX chain to connect to the IGH.
The 48t and the 24t chainrings bolt to each other, using 5 M6 bolts.
Now comes the interesting part.
The 12-tooth 3/4" clutch is moved to the right side of the engine.
The clutch will spin clockwise, which is ok.
The pull start, fan shroud and fan is discarded.
Of course, the engine now needs an electric starter,
or a cable-activated manual/centrifugal clutch,
The clutch needs to be mounted on the flywheel.
To do so, the flywheel needs to be removed and
a flat 4" circle spot-faced/machined to accept a
5-bolt go-kart sprocket hub.
4" x 4" Go-Kart Live Axle Hub with 1" to 3/4" Step-Down | eBay
A 3/4" keyed shaft about 3" long is welded into the hub.
So now the clutch slides onto the shafted hub, which is
bolted onto the engine flywheel.
A #41 chain connects to the chainring, and
completes the conversion.
The weak link MIGHT be the flywheel nut,
which could be locktited, lockwashered or
the flywheel nut can be brazed to the crankshaft.
This is my Plan B, in case my Plan A, which is
running engine power through the bottom bracket fails.
No expensive custom welding or fabricating parts
Minor machining and welding.
No relying on thin 30mm BB bearings.
The gearing ratio issues can been resolved. by using an internal gear hub(IGH) on the rear wheel.
Ratios range from 1.00 to 3.25:1.
With a 12t clutch, a 48t and 24t chainring and a 25t rear sprockets, gearing ranges from 4.17 to 13.54:1.
Or a 120t timing pulley and a 23t pulley clutch, a 27t chainring and a 25t rear sprocket results in 4.83 to 15.7:1
Perfect in both cases.
A #41 48t chainring sprocket on the right side of the BB is drilled to bolt to an SBP freewheel,
which screws onto the SBP crank arm.
410 A 48 Tooth for 5 hole Flange type freewheel (staton-inc.com)
Front Freewheel - Heavy Duty - Sick Bike Parts
Front Freewheel - Heavy Duty - Sick Bike Parts
The inboard 24t chainring is 1/2 x 1/8 and uses a BMX chain to connect to the IGH.
The 48t and the 24t chainrings bolt to each other, using 5 M6 bolts.
Now comes the interesting part.
The 12-tooth 3/4" clutch is moved to the right side of the engine.
The clutch will spin clockwise, which is ok.
The pull start, fan shroud and fan is discarded.
Of course, the engine now needs an electric starter,
or a cable-activated manual/centrifugal clutch,
The clutch needs to be mounted on the flywheel.
To do so, the flywheel needs to be removed and
a flat 4" circle spot-faced/machined to accept a
5-bolt go-kart sprocket hub.
4" x 4" Go-Kart Live Axle Hub with 1" to 3/4" Step-Down | eBay
A 3/4" keyed shaft about 3" long is welded into the hub.
So now the clutch slides onto the shafted hub, which is
bolted onto the engine flywheel.
A #41 chain connects to the chainring, and
completes the conversion.
The weak link MIGHT be the flywheel nut,
which could be locktited, lockwashered or
the flywheel nut can be brazed to the crankshaft.
This is my Plan B, in case my Plan A, which is
running engine power through the bottom bracket fails.
No expensive custom welding or fabricating parts
Minor machining and welding.
No relying on thin 30mm BB bearings.
Last edited:
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