Dishless disc hub

jakerollo · Mar 18, 2005

A major weakness of the IS disc standard is that most, if not all, front disc hubs are dished. This leads to a weaker wheel with unequal spoke tension. Some hub manufactures make the disc side flange diameter larger than the other. It helps a little but it is not perfect.

On some forks there is room for the disk to be moved further towards the left leg. That is the case of my fork. A On-One Ti fork.

I have made a hub with equally space flanges and a disc adapter that moves the calliper the right amount to the left. The hub also features large axle ends to make a good connection with the fork ends, bolt on instead of QR, adjustable bearing preload and a 20mm axle.

I wonder how the big companies could agree over a standard that could easily have been a lot better by making it possible to make non dished wheels.

kept man · Mar 19, 2005

That sir, is a great idea.

What can you do for rear hubs next?

jakerollo · Mar 19, 2005

kept man said:
That sir, is a great idea.

What can you do for rear hubs next?

I have a singlespeed rearhub on the drawing board. I will probably never make a cassette style multispeed rearhub since I have Rohloff Speehub.

The singlespeed hub will feature a rollerclutch mechanism with infinite engagement points and maybe also with variable engagement degree.

It will have a 17 mm axle and have large diameter axle ends like the front hub. It will also be a bolt on design with M8 bolts.

Five bearings will be used, two on the none driveside (maybe fixed) to support the hubshell, two in the driveside to support the hubshell, and one to support the rollerclutch mechanism. All bearings will be id17, od30, w7 and the preload will be adjustable.

The flanges will be wide spaced, wider than most production singlespeed hubs.

It will use a standard ISO threaded track cog, 1.375" x 24tpi.

Axle will be aluminium or titanium with stainless steel ends to avoid wear. Hubshell will be stainless steel. Rollerclutch will be hardened steel.

weight will be around 400g including track cog.

All for now. Maybe drawings and more on materials later.

20.100 FR · Mar 19, 2005

I like your idea very much.

I ride 29er, and we need a wider spaced hub to have the same angles for the spokes compared to a 26, thus the same lateral rigidity.

I'am also working on an internal transmission frame, and would need a fixed gear rear hub with disk mounts.

I would be very interested in your drawings, if you are willing to share.

vortex_fr@yahoo.fr

jakerollo · Mar 19, 2005

No Problem

20.100 FR said:
I like your idea very much.

Thank you!

20.100 FR said:
I would be very interested in your drawings, if you are willing to share.

On Monday or Tuesday I will send you the drawings for a fixed disc rear hub. I have them at work. It should be quite simple.

Zubi · Mar 21, 2005

Interesting,

But only 1 question: Have you think on the braking forces? How would spoke tension be in this situation?

jakerollo · Mar 21, 2005

Zubi said:
Interesting,

But only 1 question: Have you think on the braking forces? How would spoke tension be in this situation?

It should be a great advantage to have equal spoke tension on the two sides. The forces from the disc is distributed through the hubshell to both flanges. When someone states that there is a "breaking side" on a wheel it makes no sense. That would mean that the shell twists under breaking. That would lead to a immediate failure of the shell. This also makes it clear why the shell should be like a pipe with a large diameter. It is the hardest shape to twist.

That means that my hub pulls with the same force on more eyelets than a normal dished disc hub. For a 32 hole wheel that means that the hub and rim is equally loaded in 16 holes each where a normal disc hub has a high load on 8 holes and higher load on 8 other holes.

20.100 FR:
Drawings tomorrow...

Zubi · Mar 22, 2005

jakerollo said:
It should be a great advantage to have equal spoke tension on the two sides. The forces from the disc is distributed through the hubshell to both flanges. When someone states that there is a "breaking side" on a wheel it makes no sense. That would mean that the shell twists under breaking. That would lead to a immediate failure of the shell. This also makes it clear why the shell should be like a pipe with a large diameter. It is the hardest shape to twist.

That means that my hub pulls with the same force on more eyelets than a normal dished disc hub. For a 32 hole wheel that means that the hub and rim is equally loaded in 16 holes each where a normal disc hub has a high load on 8 holes and higher load on 8 other holes.

20.100 FR:
Drawings tomorrow...

Then when wheel-makers choose different spokes configuration for disc side is due to they have dished disc hubs, and not owing to the disc-brake forces. Is this correct?

jakerollo · Mar 22, 2005

Correct

Zubi said:
Then when wheel-makers choose different spokes configuration for disc side is due to they have dished disc hubs, and not owing to the disc-brake forces. Is this correct?

Correct

20.100 FR · Mar 22, 2005

Waiting for it !

I have acces to ProE, Catia, SolidWorks, but send whatever format you have got !

It would be interesting to have an idea of the stifness of spokes compared to the torsonial rigidity of a hub....
I have to test some FEM software tommorow afternoon (european time). Be fast enough jakerollo if you want to see fast results !

I love straight pull spokes, and will try to make mines like that.

Warp · Mar 22, 2005

Sell the stuff, man!!!

Before some malintentioned big corporation realizes about how good your idea is.

jakerollo · Mar 23, 2005

20.100 FR said:
Waiting for it !

I have acces to ProE, Catia, SolidWorks, but send whatever format you have got !

It would be interesting to have an idea of the stifness of spokes compared to the torsonial rigidity of a hub....
I have to test some FEM software tommorow afternoon (european time). Be fast enough jakerollo if you want to see fast results !

I love straight pull spokes, and will try to make mines like that.

Check your mailbox. Please note that the shell was designed with some kind of stainless steel in mind and axle and end in aluminium. Fell free to find the right thickness of the shell!

Remember, I have not build this yet. It is still only on the drawing bord.

Be carefull with straightpull and disc.

Disc version next week.

20.100 FR · Mar 25, 2005

I have straigh pull spokes on my 26 xmaxsl and my 29 speedcity.
I don't see a problem here, except that it needs a 5 axis CNC to make the hole in the right direction.

jakerollo · Mar 25, 2005

The problem with straight pull

20.100 FR said:
I have straigh pull spokes on my 26 xmaxsl and my 29 speedcity.
I don't see a problem here, except that it needs a 5 axis CNC to make the hole in the right direction.

A good wheel for me should meet three criteria:

1: High torsional stiffness. If you apply a torque to the hub, rear or front, it has to transfer this torque to the rim in a way with minimal loss. The spokes is the connection between the hub and the rim so they should be placed in a configuration where they are pulled instead of bent. They are pulled (and pushed - not good) in three cross pattern.

2: High sideways stiffness. Minimal flex should appear when a force, normal to the wheel, is applied to the rim. A stiffer wheel is possible by

- increasing the spoke hole diameter

- increasing the flanges to center distance

- increasing the spoke tension.

3: Some radial forgiveness. To absorb some hits and shocks a wheel should have some radial forgiveness. It is quite complex to figure out how straight pull spokes and three cross pattern spokes behave different from each other when radial forces is applied to the rim.

All these parameters should be adjusted to each other with the best set of compromises to build a good wheel. And then there is material choice, axle -width and -diameter, connection to the fork, bearings, rim rigidity and probably a lot more parameters.

[EDIT] What kind of holes can you make with a 5 axis milling CNC that you can't make with a traditional manual milling machine? [/EDIT]

Warp · Mar 25, 2005

jakerollo said:
[EDIT] What kind of holes can you make with a 5 axis milling CNC that you can't make with a traditional manual milling machine? [/EDIT]

Agreed. The 5 axis are needed to mill. To drill you only need a (duh!) drill, a lot of patience and good fixtures.

MD Bullit · Mar 26, 2005

jakerollo said:
I have a singlespeed rearhub on the drawing board. I will probably never make a cassette style multispeed rearhub since I have Rohloff Speehub.

The singlespeed hub will feature a rollerclutch mechanism with infinite engagement points and maybe also with variable engagement degree.

It will use a standard ISO threaded track cog, 1.375" x 24tpi.

If you used a threadec track cog on a cassette hub, how would you ever remove the cog? You wouldn't be able to hold the cassette body immobile to remove the tightly threaded on track cog.

jakerollo · Mar 26, 2005

MD Bullit said:
If you used a threadec track cog on a cassette hub, how would you ever remove the cog? You wouldn't be able to hold the cassette body immobile to remove the tightly threaded on track cog.

I have thought this through. Because I can't show you the drawings right now (I am a few hundred kilometers away from them) it is a little difficult to explain how it will work. But I will give it a try:

The engagement mechanism is meant to pop right of the shell and axle when the hub is not mounted in the frame and the axle is disassembled. A "inverse" part to this mechanism with the track cog on, should be mounted in a vise. The engagement mechanism will then be fixed both clockwise and counterclockwise and the cog should be easy to remove with a chain whip.

20.100 FR · Mar 27, 2005

Jakerello : i agree with you on the overal function needed by a good whellset.
I would like to stress out that you can increase the lateral stifness AND increase the vertical forgiveness by using the more "spread out" pattern of the spokes like you did on your hub.

This is my problem with 29er whells that propotionnaly have a "close" spoke pattern.

jakerollo said:
- increasing the spoke tension.

This is a common mistake.
You will NOT get a stiffer whell with higher spoke tension (assuming you don't allow the tension to go so low that there are not any more traction in the spoke when it's at the bottom).

This is the same as on a suspension : you will not change the stiffness of a spring with a higher preload, you need to change the spring itself. (this is why there are several spring available for forks).

If you want stiff spokes, you need a material with a high young modulus, and a shape (mainly the section) the bigger possible (as you said)

Straight pull spokes can be used in a 3 cross pattern. The difference is just in the head. The fact that it's straight allows a greater stifness of the spoke compared to the same spoke with a bent head.

You have to machine the head so that it has the correct angle for the 3 cross pattern and so that it goes towards the center of the rim. So there is 2 angles here, needing a 5 axis mill, or good fixture to do it manually.

jakerollo · Mar 27, 2005

This is a common mistake.
You will NOT get a stiffer whell with higher spoke tension (assuming you don't allow the tension to go so low that there are not any more traction in the spoke when it's at the bottom).

This is the same as on a suspension : you will not change the stiffness of a spring with a higher preload, you need to change the spring itself. (this is why there are several spring available for forks).

If you want stiff spokes, you need a material with a high young modulus, and a shape (mainly the section) the bigger possible (as you said)

Straight pull spokes can be used in a 3 cross pattern. The difference is just in the head. The fact that it's straight allows a greater stifness of the spoke compared to the same spoke with a bent head.

You have to machine the head so that it has the correct angle for the 3 cross pattern and so that it goes towards the center of the rim. So there is 2 angles here, needing a 5 axis mill, or good fixture to do it manually.

Thank you! You just made me realize that "straight pull" is not the same as "radial lacing". I am very sorry for my ignorance. Straight pull is a great advantage. Radial lacing is not.

I will agree on the spoke tension question (almost). Steel is indeed a linear material with constant Young's modulus over its elastic region. But, as you say, the spokes would need to have just a little bit of preload. I have often seen poorly laced wheels where the rim had to do the spokes job.

My "greater spoke tension" statement should be "proper spoke tension".

I also better like more spokes, to some point at least, instead of few. This does, as you say, increase the sideways stiffness of the wheel. A rim should be supported as many places as possible because of aluminiums lack of fatigue limit. This is a contradiction to what i said in "3" about radial forgiveness. But I guess you can't have it all...

It should not be too hard to machine a straight pull hub, but it would take some time.

20.100 FR · Mar 28, 2005

Technical english can be confusing, especially when a Danish talks with a French

Radial lacing is the best for a whell with no torque transmited to the hub, such as a front whell with v brakes. As the load on the frange has a different direction than on a 2 or 3 cross, you need a stong frange.

The question of the number of spokes is very intersting. For sure it would be better to have a lot of low weight spokes connected to the rim, so that they give a more "constant" support.

But i think that the problem of this approach is aerodynamics. A lot of spokes would lead to sensibility to lateral wind, and more important would create a lot of drag while spinning.

I was thinking of using 36 spokes on my whells, but with light and aerodynamic spokes like Sapin CX rays (available in straight head).

Rolf whells used very low spokes count. They connected the spokes head by two (one from the right and one from the left), removing lateral stress on the rim. But it gives less support to the rim between the spokes.
May be it would be interesting to use this approach ?

20.100 FR · Mar 31, 2005

Here is a picture of an edco straight pull hub.

Edco (Ch) as been bought by sapim (Be) in 2001, but i haven't seen any products yet...

Sapin profides all its bend spokes with a straight pull option, such as the famous cx-ray :

Vacation Special · Apr 16, 2005

Would it be possible to make a hub with the disc mount being concentric to the flange and move the non-disc side over a bit to compensate? Does anyone do this? I look around and didn't find anything.

jakerollo · Apr 16, 2005

Vacation Special said:
Would it be possible to make a hub with the disc mount being concentric to the flange and move the non-disc side over a bit to compensate? Does anyone do this? I look around and didn't find anything.

I am not absolutely sure I now what you mean, but if I understand you correct your idea would make very little, if any, room for the brake caliper. Some calipers does not require much space but most does.

Low_Rider · Apr 17, 2005

Good stuff - I don't understand why I didn't check this thread 4 weeks ago!! If you don't mind, it would be great if you could send me a copy of your drawings!! Any format is fine.

Do you have any plans to make a batch of hubs, or create a buisness, or are you just 'tinkering' for the moment.

Keep us posted!

Cheers, Dave.

jakerollo · Apr 17, 2005

Low_Rider said:
Good stuff - I don't understand why I didn't check this thread 4 weeks ago!! If you don't mind, it would be great if you could send me a copy of your drawings!! Any format is fine.

It might take a week or two until I can send you the drawings for the front hub. I am not near a computer with cad/cam software right now and I don't have the files where I am typing now.

Do you have any plans to make a batch of hubs, or create a buisness, or are you just 'tinkering' for the moment.

I have a ideas for a few other things (the rear hub I mentioned above) but this front hub would not be suited for mass production because it should be different for each fork and brake. Not all forks have the dropout lining up with the inner side of the leg and different calipers require different amount of space. Also the axle ends should be made to fit each fork.

If I at some point start a business I would make these kind of special solutions on order. It would be more expensive but there should be a market.

Vacation Special · Apr 17, 2005

jakerollo said:
I am not absolutely sure I now what you mean, but if I understand you correct your idea would make very little, if any, room for the brake caliper. Some calipers does not require much space but most does.

Good point, I guess only about 1 cm could realistically be gained, depending on the brake.

Dishless disc hub

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