Anyone Running Power THRU the Bottom Bracket?

[5-7HEAVEN]

I don’t think so.

That’s what threw me on an expensive and time consuming tangent.

It took me a long time looking for correctly sized bearings and shafts,

only to realize that even expensive, one-off bearings won’t fit.....

only inexpensive, widely available bronze bushings.

 

[5-7HEAVEN]

Those look nice. Think you can find thin enough needle bearings that could fit between the 2 shafts?

Dan, I did some research.

There IS a 1.25"(31.75mm) x 3/4" x 6" hollow shaft that can be turned down to 30mm(1.1811").

It costs $19 on Ebay.

This can be cut to 30mm at the center, where it enters the BB, and
1"(25.4mm) along the left side and right side rest of the shaft.
The shaft's 3/4" ID can be reamed at both ends to accept the 5/8" x 13/16" x 3/4" needle bearings.

One sprocket can be welded onto the keyless shaft.
The sprocket on the other side can have its freewheel adaptor welded onto 2 lock collars,
then slid onto the 1" section of the shaft.

Using this method, the BB sprockets, bearings
and spindle can all be serviced or replaced without cutting the main shaft in two.


It SHOULD work.

However, it'll need a LOT more machine work to do it this way.

 

[5-7HEAVEN]

The needle bearings in the shaft would only enhance(maybe) the pedaling.

Not worth it, in my opinion, to spend $50 more for this.

 

[5-7HEAVEN]

I'm also leery about using 30mm bearings in the BB,
instead of 25mm ones.

I'll try to find pics of the 30mm bearing next to other bearings,
and the review on it.

Read this:

BB86/BB92 Bottom Brackets with a 30mm or SRAM DUB Crankset - A recipe for disaster - Hambini Engineering

A common question I am often emailed about is asking if I can supply a bottom bracket that will allow a 30mm crank to be fitted into a BB86 bike frame. This

www.hambini.com

 

[5-7HEAVEN]

So I'll machine the shaft to fit the bottom bracket(BB).....

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

and 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.


I'll have pictures of the entire assembly,

exploded, then assembled.....

when this BB contraption is completed.

 

[Chainlube]

Well, it was nothing I did!

 

[5-7HEAVEN]

 

[5-7HEAVEN]

My quote on July 14, 2020, post #87:

"Another night, another bright idea.....

This time, it's running engine power thru concentric shafts in the BB.

To be continued....."

And that's when it all started to come together.

 

[5-7HEAVEN]

I'm getting sidetracked again.....

What if I connect the clutch on the engine directly with the bottom bracket(BB) spindle?

No jackshafts!

I have a clutch with a 23-tooth timing pulley.

If I find a HUGE!! timing pulley, I can weld it onto the 1" spindle.

That'd mean the engine would have to be mounted several more inches towards the right.....

or the left-side main shaft would have to be extended further.

Gearing will rise: I can only use 5 speeds.

Good enough.



Update: I bought a used 150-tooth timing pulley on Ebay for $10.
It's 9.375" diameter, same as a 59-tooth chainring.

 

[5-7HEAVEN]

Eureka!

I have a few adaptors from Staton-inc.com to mount freewheels to shafts of various sizes.
The freewheel threads are 1.37 x 24tpi.

Some freewheels are left-hand threaded and some are right-hand threaded.

These adaptors slide onto 5/8", 3/4" and 1" jackshafts or the BB spindles.

Then the adaptors screw onto freewheels, which then bolt onto 5-hole sprockets.

The adaptors' threads are the same size as my bottom bracket(BB)shell!

That's the bike frame itself.

My BB was removed, so I tried to thread the left-side Staton freewheel adaptor directly onto the bike.....

IT FIT!!!!!

The right-side adaptor fits too!

All I have to do is bore both adaptors to fit bronze bushings for the 1" hollow main shaft.

Then I use 1" lock collars to secure the slip-fit bushing into the BB!
(At least one bearing has to be slip-fit, so the bearings and shaft can be removed and serviced.)

No fancy bottom brackets are needed, no 25mm-30mm skinny bearings.

No need to machine the main shaft from 25.4mm to 25mm diameter, to fit the 25mm bearings.