Dual freewheel BB

[HAL9000v2.0]

After plaing with different rc setup I found out that the most anoing sound is comming form freewhels. As Shimano made its silent frewheels obsolete i was thinking of making one myself and came out with this idea:
Tripple coaxial axle drive that fits into standtard 1,375"x24TPI x68mm BB. The input sprocket can be made on left side also.
It will be PITA to make it with standard parts in 35mm dia but I think it is doable. Here is the idea:

 

[boostjuice]

Now that's thinking outside the box. Nice concept Hal! can you build two?

 

[Miles]

Nice idea to keep things within the BB shell. I think the problem would be getting enough torque capacity for the clutches closest to the centre. 16mm ID 16mm long (26mm with bearings) roller clutch capacity is 20 Nm.

I worked out a symmetrical one with external sprag clutches but the Q factor mounts up....

 

[HAL9000v2.0]

I know. That is why I wrote that I don't think it can be done well in 35mm. I think the minimal BB dia will be around 55mm.
There is two way to construct this:
1. from crank axle to outside
2. from bb dia inside.
I think 22 mm crank axle will be sufficient for the bearing to hold.
BTW. I have tested 16 mm one way needle bearing 20mm wide and it slips/brakes at 143Nm. I did that because the Nm values in SKF catalogue doesn't seams right.

 

[Miles]

I know. That is why I wrote that I don't think it can be done well in 35mm. I think the minimal BB dia will be around 55mm.

Let's hope the BB30 standard becomes more widely adopted. That still only gets you to 42mm ID, though.

 

[Miles]

BTW. I have tested 16 mm one way needle bearing 20mm wide and it slips/brakes at 143Nm. I did that because the Nm values in SKF catalogue doesn't seams right.

That's good to know. Peak torque capacity is usually double the nominal capacity rating and even that's a long way from breaking point, I guess....

 

[liveforphysics]

I like everything about it, except the little needle sprague clutches.

If you're going to use them, you gotta make sure the surfaces of those areas they bite upon are exactly the surface roughness, hardness, alloy, and only ever see the exact recommended lube.

The wrong lube will have them skipping and destroyed in short time, and the wrong surfaces (or anything aluminum etc) will result in prompt failure.

So make sure if you're going to make a proto, you research the heck out of the surface requirements to get some decent life.

 

[nikos7]

I know. That is why I wrote that I don't think it can be done well in 35mm. I think the minimal BB dia will be around 55mm.
There is two way to construct this:
1. from crank axle to outside
2. from bb dia inside.
I think 22 mm crank axle will be sufficient for the bearing to hold.
BTW. I have tested 16 mm one way needle bearing 20mm wide and it slips/brakes at 143Nm. I did that because the Nm values in SKF catalogue doesn't seams right.

Shimano cranksets with Hollowtech II (XTR, XT, LX, etc) have a 24mm OD (and non-standard proprietary bearings) on their crank axle and they hold up great...

 

[HAL9000v2.0]

I think BB30 with hollowtech II will be the way to do it...

 

[HAL9000v2.0]

I like everything about it, except the little needle sprague clutches.

If you're going to use them, you gotta make sure the surfaces of those areas they bite upon are exactly the surface roughness, hardness, alloy, and only ever see the exact recommended lube.

The wrong lube will have them skipping and destroyed in short time, and the wrong surfaces (or anything aluminum etc) will result in prompt failure.

So make sure if you're going to make a proto, you research the heck out of the surface requirements to get some decent life.

Thet is general idea, to make it from thin hardened steel and use tubes as inner and outher bearing shell at the same time.

It should be around 45% lighter then standard alu bb and two freewheels.

 

[MotoMel]

I know that this is an old thread but ... http://www.youtube.com/watch?v=ztM-UZ3oaqk and more generally http://www.youtube.com/user/BikeMotive?feature=mhee

'Twasn't easy.


or cheap.


or quick.


or painless.

But if I don't look at the financials, it has been some fun...