Anyone Running Power THRU the Bottom Bracket?

[5-7HEAVEN]

So I'll machine the adaptors to install bushings for the 1" hollow shaft.....

then weld either the 42t sprocket and 24t sprocket onto both sides of the shaft.....

or weld the 150-tooth timing pulley and 24t sprocket onto both sides of the shaft.....
(still undecided If I'm using 10t clutch/22t jack/10t jack and 42t sprocket,
ORRR the 150t pulley and 23t pulley clutch, on the left side.)

UPDATE: I decided to run power from the engine's clutch, directly to the BB.

No jackshafts.

then slide the pedaling shaft into the hollow shaft.....

then bolt the aluminum SBP crank arms onto the shaft.....

and connect to the 24t chainring sprocket.....

so there it is, in a nutshell.

 

[5-7HEAVEN]

I did some measuring.....

Good news is that the 212cc engine will still remain centered in the bike’s frame.

Both left and right pedals should clear the engine.

Bad news is that the 6” hollow main shaft on the engine side is too short.

The total length on the hollow main shaft is only 6" long.

An 8” shaft needs to be made.

I have a inner shaft that’s 12” long.
It has the correct ends to attach the crank arms.

Measuring the diameters of the cog clutch and the 150t on the hollow main shaft, there’s little more than 3” distance between the two pulleys.

All good for Plan C

 

[Frogslayer]

You're getting so close!

 

[5-7HEAVEN]

Yes, Frog. So close.

I'm set to go to the machine shop.

1.Machine the custom 3/4" bottom bracket (BB) spindle down to 5/8" diameter.

2.Install 5/8" spindle and bushings into the hollow 1" main shaft.

3.Weld the left-side sprocket hub onto the main shaft.

4. Weld the right-side sprocket hub to two lock collars, then bolt onto the main shaft.
This is so the shafts can be removed and serviced.

The BB shell on the bike is very small, with 1.37" inside diameter(ID).

The 2 BB adaptors are 1.37" OD and thread into the shell.

They need boring, from 1" to 1.060".

Then the shop will install and ream the .060" bushings to fit the 1" hollow shaft.

If the .060" bushings fail, the adaptors and new bushings will be milled a little larger.

If that fails, then I'll change over to oversize/external BB brackets and 25mm bearings.

 

[Sidewinder Jerry]

Yes, Frog. So close.

I'm set to go to the machine shop.

1.Machine the custom 3/4" bottom bracket (BB) spindle down to 5/8" diameter.

2.Install 5/8" spindle and bushings into the hollow 1" main shaft.

3.Weld the left-side sprocket hub onto the main shaft.

4. Weld the right-side sprocket hub to two lock collars, then bolt onto the main shaft.
This is so the shafts can be removed and serviced.

The BB shell on the bike is very small, with 1.37" inside diameter(ID).

The 2 BB adaptors are 1.37" OD and thread into the shell.

They need boring, from 1" to 1.060".

Then the shop will install and ream the .060" bushings to fit the 1" hollow shaft.

If the .060" bushings fail, the adaptors and new bushings will be milled a little larger.

If that fails, then I'll change over to oversize/external BB brackets and 25mm bearings.

I'm so ready to see the final product. Got my shifter working perfectly now. Like you went through several heartaches working out issues.

 

[5-7HEAVEN]

I’m glad your shifter’s working perfectly.

Yep, still have heartaches.

The cheapest and simplest solution is to clearance the 25mm bearings about .5mm oversize.

Next cheapest solution is milling the hollow shaft by .5mm.

Most expensive, difficult and undependable is boring these BB adaptors and bushings.

 

[5-7HEAVEN]

This is a mock up.

The inner shaft still has to be machined to fit.

The adaptor in front would need to be bored 1.060” inside diameter.

The 1.25” outside diameter bronze bushing needs to be machined down to 1.056”.

Of course, the hollow shaft needs to be trimmed about 5”.

The Max-Torque clutch has 23 teeth, and the driven sprocket has 150 teeth.

The drive sprocket on the left has 24teeth.

 

[5-7HEAVEN]

That’s the 150t sprocket and hub that belts to the 23t clutch.

 

[5-7HEAVEN]

So would you be deleting the pedals entirely then? I can't think of a way to send power through the bottom bracket without spinning the pedals as well, unless you engineer something crazy like a bottom bracket with two concentric shafts.

Not to discourage you or anything, but I'm having trouble seeing where this is going. Seems to me like it's just reinventing the wheel.

And here it is!

I engineered something crazy, like a bottom bracket with two concentric shafts.

The pedals will be working, as you will see.

The right-side SBP crank arm and freewheel separates pedal power from engine power.

The 212cc engine will twist the hollow, outer main shaft and the right 24t chainring.

The freewheel on the SBP crank arm prevents both pedals from spinning.

Both pedals are bolted onto the inner shaft, independent of the outer main shaft.

Using 5 bolts, this same freewheel then connects to the 24t chainring sprocket.

That’s how the pedals connect and drive the rear sprockets.

It looks odd, not to have a sprocket on the SBP crank arm.

Only the freewheel is needed there, not a sprocket.

 

[5-7HEAVEN]

Or build our own left hand lower drive...

The Left side of the pedal crank set...

Then too a reversed internal left hand rear gear set...
Of course we would need to rely on our machine shop person to build this for us... Ha
View attachment 97771


Part of the trick is too use a 140,,, 160,,, or 200mm fat tire bike frame...

Use a narrower hub so we can add a left hand side engine drive sproket,,, or add a thinner right hand side cassette too gain more room for the engine drive side...

No Jack-shaft kit needed,,, the engine is easy to swap out since there is no Jack-shaft brakets in the way """if"" we need too swap out engines,,, and the pedal bike chain and gears remain untouched...

We will put a wider crank set stem on,,, a large floating bearing so the 2 sprokets turn by engine power on Left side...
1 sproket the driven,,, the other will be the drive that will feed power to rear hub...

Yes,,, thinking out side the box,,, at least there wont be no Jack-shaft kit ...
And we get to run the heavy duty drive chain

Still designing Don

When the rear tire is going around,,, both chains to sprokets will be spinning,,, let clutch out and Zoom Zoom...

We will find out if our machinest can add a nutral in the rear internal gear hub...
That way we can pedal the bike with no engine drive chain drag...

The drawing is a 2+ 2 gear set for the engine power side...

I’m revisiting posts in this thread to respond to:

Don, if I’m reading you correctly, you do not need a machinist to create this idea of yours.

You can do it!!

Are you eliminating the jack shaft and trying to connect the engine to the bottom bracket?

It’s been done before. In fact, Sportsman Flyer has this option.

Also, I’m helping a fellow member create the same setup I think you’re trying to.

Basically, the engine clutch drives a chain to a large chainring idler sprocket.
This sprocket is bolted to another chainring sprocket.

Both of these chainrings are on the left side of the spindle.

Then that chainring is chained to the rear wheel sprocket.

Using a large 4-stroke engine allows you to create a gear ratio low enough to power the bike.

It’d be very difficult to gear a 2-stroke engine, low enough to optimize its potential.

Thankfully, it’s easier for Crimson Prince, the member I’m helping.

He’s using a pocket bike engine with a tiny 6-tooth clutch sprocket and a 54t chainring sprocket.

Since this sprocket has 8mm pitch, the 54t chainring is less than 5.5” diameter.

That’s the size of a 34t bike sprocket.

So, the engine connects to the 54t.
Then, this sprocket bolts onto a smaller chainring sprocket.
This is then chained to the rear wheel sprocket.

But won’t the pedals spin, when the engine drives the chainring sprockets?

No!!

The secret to its success is that the chainring sprockets run on IDLER BEARINGS!

This means that both sprockets won't spin, when the pedals and their spindle spin.

They have bearings which allow them to spin, independently of the shaft.

In fact, the chainring drive sprocket can “float” around the bottom bracket spindle.

That’s because the 54t driven sprocket is literally supporting the 25t drive sprocket in midair!

From there, it’s a chain to the rear wheel sprocket.

Seems simple, right?