Anyone Running Power THRU the Bottom Bracket?

[5-7HEAVEN]

Dan is right.

The motor chain must turn the shorter, outer(hollow) shaft.

The pedals spin the longer, inner shaft.

 

[Chainlube]

The outer (hollow) shaft would have to be some heavy walled molly tubing to withstand the torque of the 212.

 

[CrazyDan]

I think if you want to make this viable, you will need to use an outer shaft milled to be just under the BB inner diameter and external cups to hold much larger bearings. Then you can run bearings between the hollow and solid shafts. I would use 4+ sealed bearings between the 2 shafts.

 

[5-7HEAVEN]

Yes, I agree.

 

[5-7HEAVEN]

I'm putting this project of running engine power thru the bottom bracket(BB) on the back burner.

After months of racking my brain and buying parts to make it work, I've realized:

1)It takes a LOT of time to design it and source parts.
2) Because the spindle is hollow and keyless, the hubs are VERY expensive and extremely hard to find.
And after you buy them, you still need machining to do.
3 No one sells parts to spin a 1.125" shaft thru the BB.
4))Parts aren't off the shelf. It takes time and $ to buy stuff, which end up not fitting.
5)My idea of using gokart and assembly line pulleys proved very expensive and VERY heavy.
The pulleys, shafts and adaptors weigh over 10 pounds!

I should've used sprockets, not pulleys.

I'm not giving up, though, just setting it aside to make my 212cc build finish earlier.


So I'll just use a a Max Torque 10t clutch, 5 feet of chain, 22t and 10t jackshaft sprockets and a 42t chainring sprocket.

I thought up my entire driveline, from clutch to chainring in less than 2 hours.
And it only cost $100.

And I've spent MONTHS! and $$$ working on sending power through the BB!

 

[5-7HEAVEN]

Well, ya can't keep a good project down, lol!

The physical weight of the pulleys was VERY discouraging,
as well as the fact that its expensive and rare pulleys and hubs needed machining to fit.

When I decided to use generic Ebay sprockets, this project was rejuvenated!

Selecting proper gear ratios was easy: I wanted 5.0:1 or better gear ratio in final drive(7th gear).

So a 10t clutch and a driven 22t jackshaft = 2.2:1.....
A driving10t jackshaft and a 42t left-side driven chainring sprocket = 4.2:1.....
A 24t right-side driving chainring sprocket and a 14t driven 7th gear = .5833:1.....

2.2 x 4.2 x .5833 = 5.39:1.....

perfect.

 

[5-7HEAVEN]

Hopefully, I'll meet up with member Crimson Prince today.

He can upload pictures of this project and my fantastic "battery box".

 

[5-7HEAVEN]

Not much machining to do.

The 25.4mm(1") hollow main shaft needs to be turned down to 25mm.
This is because most bottom brackets(BB)have 24mm-25mm-30mm sealed bearings.

There are no 25.4mm(1.00") bearings for any BB's.

The 1" hollow shaft is 6" (~152mm)long.
About 120mm of it needs machining to 25mm.

That's the part that slides thru the BB's 25mm bearings.

The 42t chainring needs welding to the hollow shaft on the left side(1").

Both ends of this shaft need bronze bushings installed and reamed to accept the 5/8" inner shaft.

MBRebel.com sells a BB spindle that's 13" long and 3/4" diameter, with tapered ends.

To make it fit, the entire shaft just needs to be turned to 5/8".

A 24t sprocket and adaptor slips onto the right side of the shaft, which is shaved to 25mm.

This hollow shaft has no keyway to secure its sprockets.

If both left-side and right-side sprockets are welded on, there's no access to the BB's bearings.

SBP's crank arms will bolt directly to the 13" inner shaft., clearing the 212cc engine.

The arms are unmodified
and should clear both sides.

If 13" proves to be too long, the shaft can be shortened.

Chain size is #40, left-side.
Standard multi-speed chain is the weakest link.

 

[CrazyDan]

Sounds like you are almost on the same train of thought as me, just a boxcar away. That should work too, I just hate bronze bushings.
If you make external cups for the outer shaft you can use a much larger outer shaft. Then you can use sealed bearings through it for the inner shaft to ride on. Use as much space as you can in the BB and have the bearings outside of it.

 

[5-7HEAVEN]

To secure the 24t without welding it to the main shaft, the sprocket and shaft adaptor from Staton slips onto the shaft's right side.

Then, 2 locking collars slide onto the shaft.
The collars will be welded to Staton's adaptor, but NOT to the sprocket OR the hollow main shaft.

This should make the entire bottom bracket solid, but removable.

Now to find the correct bottom bracket to fit my frame!