For discussion: Offset spoke beds for everyone?

[echelon_john]

Saw a mention of OSB rims which got me thinking.

Would it make sense for rim makers to ONLY make off-center rims? Sounds stupid, right, but hear me out:

- It's easy to understand the benefits of an OSB rear to make up for poor dish with wide cassettes

- The loads/stresses that are on a front wheel are much lighter overall than a rear wheel

- Hence, the slight "dishing" of the front wheel with an OSB wouldn't cause any meaningful compromise to longevity/performance

- It would also be helpful on front wheels for disc brake bikes, where the offset would help compensate for the disk rotor.

What think ye?

[saab2000]

http://www.reactiongifs.com/r/2013/09/Dwight-Schrute-Shakes-Head-and-Rolls-Eyes.gif


Rear wheel and disc wheel only. But they should be available for rears. I can't wait until I'm able to get a set of the new Pacenti Forzas laced to the Wheels Manufacturing version of the Alchemy hub.

[oldpotatoe]

Saw a mention of OSB rims which got me thinking.

Would it make sense for rim makers to ONLY make off-center rims? Sounds stupid, right, but hear me out:

- It's easy to understand the benefits of an OSB rear to make up for poor dish with wide cassettes

- The loads/stresses that are on a front wheel are much lighter overall than a rear wheel

- Hence, the slight "dishing" of the front wheel with an OSB wouldn't cause any meaningful compromise to longevity/performance

- It would also be helpful on front wheels for disc brake bikes, where the offset would help compensate for the disk rotor.

What think ye?

For a symmetrical hub, it wouldn't help anything. It would cost people trying to sell these things a ton of time to explain why the front wheel(non disc) has offset spoke holes. It would be cheaper for rim makers.

I used to build 32h wheels with the 'crossed' spoke section(as opposed to the 'parallel' spoke section, like at the valve hole) at the seam and valve hole..the least strong parts of the rim(how my wheel building teacher taught me..1985)..but trying to explain, 'so this is why I do it, and yes, you can still get a pump head on the valve', type stuff, I stopped.

[ColonelJLloyd]

- It would also be helpful on front wheels for disc brake bikes, where the offset would help compensate for the disk rotor.


This is a thing? Not in my experience.

[Mark McM]

This is a thing? Not in my experience.

????

Just about every disc brake front wheel I've seen (for standard 100 mm front axle width) has been dished, due to the difference in right/left flange offsets. For that reason, I've built my disc brake front wheels with off center rims.

For example, the White Industries CLD disc front hub has flange offsets of 20.5mm left/34.5 mm/right, which gives it almost as much dish as an 10 speed rear hub:

http://www.avt.bike/images/White/White-Industries-Front-Center-Lock-Disc-Hub-Black.jpg

[ColonelJLloyd]

????

Guess I'm 3 for 4. The only front disc hubs I have built are SP PD-8, SP PL-8X and SRAM 900. In the case of the SP hubs, the flanges are the same diameter, 50mm apart and centered. The SRAM 900 uses a larger flange on the rotor side. I just looked back and seems I did use spokes 2mm different on the SRAM 900.

This explains, I guess, why SP disc hubs are known to cause spoke interference with the really wide TRP Spyre caliper.

Is the high/low flange design not beneficial for front disc hubs? If so why doesn't everyone go with it? Because it's heavier by a few grams?

[Mikej]

Well, to me the problem is there really isn't a problem to begin with. It seems like wheels hold up pretty well, even with the current dishing. My 32 spoke x3 King MTB / DT SWISS rimmed disc wheels hold up pretty damn good. I would say these wheels have easily taken the beating of a life time already...maybe a clyde would need 36h.

[Mark McM]

Guess I'm 3 for 4. The only front disc hubs I have built are SP PD-8, SP PL-8X and SRAM 900. In the case of the SP hubs, the flanges are the same diameter, 50mm apart and centered. The SRAM 900 uses a larger flange on the rotor side. I just looked back and seems I did use spokes 2mm different on the SRAM 900.

The SP hubs aren't dished because the have reduced flange spacing on both sides - on the left for the disc rotor, and on the right for the generator electrical connection. Everything else being equal, this means wheels built with the these hubs will be weaker and more flexible than if built with wider flange spacing.

The SRAM 900 hubs are dished, by about the same amount as a 7spd rear wheel (flange offsets 22 mm left/34 mm right).


Is the high/low flange design not beneficial for front disc hubs? If so why doesn't everyone go with it? Because it's heavier by a few grams?

There is not much structural benefit to making a flange larger than is necessary to hold the spokes. Flange size is more often governed by the mechanical requirements of the hub internals than by any affect on wheel strength/performance. For example, PowerTap hubs use large flanges due to the size (diameter) of the torque tube and electronics required for power measurement.

The most common reason for high-low rear hubs is the design of the bearings/pawls. Many rear hubs locate the ratchet ring/pawls within the right flange, so the right flange must be large to leave space for the internals. The left flange can be smaller.

On disc brake wheels, the left spoke flange must often be oversized so that the spoke holes clear the disc mounting flange - otherwise, you wouldn't be able to thread the spokes into the spoke flange. The right flange can be made standard size. The Shimano Centerlock system uses a smaller spline diameter for disc mounting, so smaller flanges can be used on both sides of the hub.

[Mark McM]

Well, to me the problem is there really isn't a problem to begin with. It seems like wheels hold up pretty well, even with the current dishing. My 32 spoke x3 King MTB / DT SWISS rimmed disc wheels hold up pretty damn good. I would say these wheels have easily taken the beating of a life time already...maybe a clyde would need 36h.

Highly dished wheels can be made with non-OCR rear rims as well. But an OCR rim will make the wheel a little more reliable, or allow a slightly lighter rim to be used with equal reliability. The same will be true for dished front wheels.