Zipp 202 NSW

[pdlpsher1]

I was under the impression that 2 cross lacing pattern (24 or 28 spokes) preferred by wheel builders make stiffer and stronger wheels over 14 spokes drive side and 7 spokes non-drive side. Isn't the sole purpose of this to save weight by having less spokes?

No. The 21 spoking pattern is done not to save weight but to increase wheel stiffness immensely. The 7 spokes on the non-drive side have much higher tension than the 12 spokes in a 24-spoke lacing pattern. Let's say you start with 12 spokes on a 24-spoke wheel. You cut and remove five spokes. To maintain the same dish the remaining 7 spokes must be tensioned higher to make up the lost force provided by the deleted 5 spokes.

[mpulsiv]

I was under the impression that 2 cross lacing pattern (24 or 28 spokes) preferred by wheel builders make stiffer and stronger wheels over 14 spokes drive side and 7 spokes non-drive side. Isn't the sole purpose of this to save weight by having less spokes?

No. The 21 spoking pattern is done not to save weight but to increase wheel stiffness immensely. The 7 spokes on the non-drive side have much higher tension than the 12 spokes in a 24-spoke lacing pattern. Let's say you start with 12 spokes on a 24-spoke wheel. You cut and remove five spokes. To maintain the same dish the remaining 7 spokes must be tensioned higher to make up the lost force provided by the deleted 5 spokes.

Oh, I didn't know this.
Is there a reason wheel builders prefer 2 cross lacing pattern? Less labor intense?
My rear is laced 2 cross with 28 CX-Ray spokes for strength, stiffness and longevity, despite average 75kg. I'd love to see on paper whether 21 spokes lacing pattern is up on par with 28 spokes. Dave published 24 vs. 28 a while back http://www.novemberbicycles.com/blog/20 ... pokes.html
Not every rim can withstand high spoke tension though.

[NovemberDave]

While it's true that having 2:1 lacing increases tension of non-drive spokes, it's not across the board true that it makes a stiffer wheel.

In order for 2:1 to convert to a stiffer wheel, the non-drive flanges need to be pushed farther out, increasing their bracing angle. On some hubs, this is done, on some it isn't. As you push the non-drive flanges out, you make the tension balance worse again, which takes back some of the tension balancing gains that the 2:1 lacing gave you in the first place. And with fewer spokes on the non-drive, some of the stiffness from the increased flange spacing is gone, too.

Increasing spoke tension beyond the point where spokes aren't going slack does nothing to increase wheel stiffness.

There are some downsides to 2:1 lacing as well, most prominent among them from my perspective being that you have quite long spans between spokes. You need a quite stiff rim that is very very straight and round in order to get the best build on 2:1 builds. The other big one is the lack of availability of parts to make optimized 2:1 builds. Doing 2:1 with standard hubs only increases non-drive tension relative to drive tension, and does nothing to increase wheel stiffness. As long as you're able to get the non-drives tight enough to not go slack within the constraints of max drive side tension, 2:1 solves for a non-existent problem while introducing the down side of that long unsupported span between NDS spokes.

[pdlpsher1]

While it's true that having 2:1 lacing increases tension of non-drive spokes, it's not across the board true that it makes a stiffer wheel.

In order for 2:1 to convert to a stiffer wheel, the non-drive flanges need to be pushed farther out, increasing their bracing angle. On some hubs, this is done, on some it isn't. As you push the non-drive flanges out, you make the tension balance worse again, which takes back some of the tension balancing gains that the 2:1 lacing gave you in the first place. And with fewer spokes on the non-drive, some of the stiffness from the increased flange spacing is gone, too.

Increasing spoke tension beyond the point where spokes aren't going slack does nothing to increase wheel stiffness.

There are some downsides to 2:1 lacing as well, most prominent among them from my perspective being that you have quite long spans between spokes. You need a quite stiff rim that is very very straight and round in order to get the best build on 2:1 builds. The other big one is the lack of availability of parts to make optimized 2:1 builds. Doing 2:1 with standard hubs only increases non-drive tension relative to drive tension, and does nothing to increase wheel stiffness. As long as you're able to get the non-drives tight enough to not go slack within the constraints of max drive side tension, 2:1 solves for a non-existent problem while introducing the down side of that long unsupported span between NDS spokes.

The German Tour magazine is my go-to source to differentiate and substantiate marketing hypes. On the lateral stiffness test for the rear wheels, the Shimano and Campy wheels with the 2:1 pattern rise above the rest with conventional lacing. Not just a little bit better but substantially better. So yes, a properly implemented 2:1 wheel is both stiffer and lighter than a conventionally laced wheel.

[NovemberDave]

Which contradicts nothing of what I said. The unequivocal statement that 2:1 is always stiffer is false, while "a properly implemented 2:1 wheel is both stiffer and lighter* than a conventionally laced wheel" is a true statement.

*except for that - that isn't necessarily true.

[mpulsiv]

Thanks Dave!
On this note, what's your take on 3 cross lacing pattern with 28 spokes? Is there a marginal advantage to it over 2 cross?

[F45]

The German Tour magazine is my go-to source to differentiate and substantiate marketing hypes. On the lateral stiffness test for the rear wheels, the Shimano and Campy wheels with the 2:1 pattern rise above the rest with conventional lacing. Not just a little bit better but substantially better. So yes, a properly implemented 2:1 wheel is both stiffer and lighter than a conventionally laced wheel.

What issue is that?

[pdlpsher1]

The German Tour magazine is my go-to source to differentiate and substantiate marketing hypes. On the lateral stiffness test for the rear wheels, the Shimano and Campy wheels with the 2:1 pattern rise above the rest with conventional lacing. Not just a little bit better but substantially better. So yes, a properly implemented 2:1 wheel is both stiffer and lighter than a conventionally laced wheel.

What issue is that?

Issue 8 2016.

Rear wheel stiffness in Newtons/mm deflection

Fulcrum Racing Quattro 21 spokes 47N/mm
Campy Bora 50 21 spokes 47N/mm
Shimano C35 21 spokes 50N/mm
Shimano C50 21 spokes 58N/mm
Zipp 202 24 spokes 37N/mm
Zipp 303 24 spokes 39N/mm
Zipp 404 24 spokes 38N/mm

[F45]

Cool, thanks.

[ergott]

Zipps use CX-Rays while the others use a heavier gauge spoke. You need to know more about the wheel to understand why those results are what they are. It's not just one aspect.

Sent from my SM-G920V using Tapatalk

[pdlpsher1]

Both Shimano and Campy use very thin spokes. They are comparable to the CX Rays. The Shimano C50 uses a very heavy aluminum/carbon bonded rim and hence it's very stiff. Thus I believe the C50's stiffness value is an outlier. The other three rims and spokes are comparable to the Zipps. In a nutshell I do believe the 2:1 lacing is responsible for their outstanding stiffness.


Sent from my iPhone using Tapatalk

[mpulsiv]

Shimano C50 is crazy stiff for 21 spokes. C35 is thin wall aluminum rim wrapped with carbon for added strength and C50 is carbon rim with a bonded aluminum brake track.

[F45]

Both Shimano and Campy use very thin spokes. They are comparable to the CX Rays. The Shimano C50 uses a very heavy aluminum/carbon bonded rim and hence it's very stiff. Thus I believe the C50's stiffness value is an outlier. The other three rims and spokes are comparable to the Zipps. In a nutshell I do believe the 2:1 lacing is responsible for their outstanding stiffness.

Then you say stuff like this that makes me think you just have internet knowledge filled in with dreamed up fantasies. Shimano c24 uses thin spokes, close to cx-ray. C35 and C50 use bladed spokes that are equivalent in weight to straight 2mm round spokes. I've weighed them.

[pdlpsher1]

Both Shimano and Campy use very thin spokes. They are comparable to the CX Rays. The Shimano C50 uses a very heavy aluminum/carbon bonded rim and hence it's very stiff. Thus I believe the C50's stiffness value is an outlier. The other three rims and spokes are comparable to the Zipps. In a nutshell I do believe the 2:1 lacing is responsible for their outstanding stiffness.

Then you say stuff like this that makes me think you just have internet knowledge filled in with dreamed up fantasies. Shimano c24 uses thin spokes, close to cx-ray. C35 and C50 use bladed spokes that are equivalent in weight to straight 2mm round spokes. I've weighed them.

I used to own a pair of the 9000 C50 and the spokes appear thin to me, but not quiet as thin as the bladed spokes on my Bora. I certainly wouldn't call them heavy spokes. What weight did you come up with? And was the spoke from the 9000 or an older series?

The C50 is truly stiff but it's way too heavy. Shimano could have easily removed some materials and made the wheels much lighter.

[Beaver]

Shimano uses "heavy" spokes, the rear ones of a C35 wheel come in a ~6g.

For comparison: http://www.wheelbuilder.com/aero-bladed-spokes/

Giant also uses 2:1 lacing and the wheels are as stiff as Shimano. They use 7 DT Aerolite as pushing spokes, 7 DT AeroComp as pulling spokes and 7 DT AeroComp on the non drive side.

If Zipp used a CX Sprint/CX Ray combo on their rear wheels, they would be much stiffer. But then again the 70kg triathlete won't notice and need it.