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Discussion Starter · #1 ·
I'm putting together a pretty light and very stiff XC race wheelset with Hope Pro II hubs and Light Bicycle 27mm hookless carbon 29er rims. I want it to be a race worth weight, under 1600 grams, but also very stiff.

I have built wheels with both Comps and Revolutions before, and wasn't disappointed by the stiffness of the revolutions on my Arch EX wheelset. I just want this wheelset to go beyond that for stiffness, hence the carbon rims.

I like the idea of CX Rays and being able to see spoke windup, which was the biggest complaint with Revolutions.

The real question is, will they build a stiffer wheel? Is it worth the extra $120

Right now my options are

1. Cx Rays all around

2. Revolutions all Around

3. Comps on Drive side rear and Brake side front. I have done this alternating on rear road wheels and have had success.

4. Comps all around, not preferred for weight.

Any thoughts are appreciated
 

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Are Sapim CX-Ray spokes worth it over DT Comp/Revolutions? For a Carbon XC Wh...

The real question is, will they build a stiffer wheel?
No.
CX Rays are Lasers (Sapim equivalent of the Revo) that are rolled flat.
No more steel in the cross section = no more stiffness.
Same weight, same performance. The only differences are aerodynamics, which are moot on a mountain bike, and the ease of preventing wind-up. Whether that's worth $120 to you is your call. It ain't to me.
 

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Bladed spokes like CX-Rays are simply easier to build than round butted spokes like Sapim Laser or DT Revs as you can see if they are winding up and use a tool to hold them strait. They are basically Lasers with the middle section flattened. Since aerodynamics aren't in play on mountain wheels there are no other advantages.
 

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If you use revolutions you could put a small dot on one side of the spokes near the nipple with a sharpie so you can see any windup and return them to neutral after each adjustment.
 

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If you use revolutions you could put a small dot on one side of the spokes near the nipple with a sharpie so you can see any windup and return them to neutral after each adjustment.
+10

I can't believe how many posts I see on a regular basis implying that you need bladed spokes to be able to keep track of spoke wind up. What non-sense...
 

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I had a chance to ride same rim tire (blunt sl, karma) combination with dt and cx rays on the same course. I found the deflection to be less in a g outs and stiffness in corners to be much better with the wheel built using the cx rays. I changed the order I had already placed with revo to upgrade to cx rays. I highly recommend cx ray spokes for xc/light weight builds.
 

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I had a chance to ride same rim tire (blunt sl, karma) combination with dt and cx rays on the same course. I found the deflection to be less in a g outs and stiffness in corners to be much better with the wheel built using the cx rays. I changed the order I had already placed with revo to upgrade to cx rays. I highly recommend cx ray spokes for xc/light weight builds.
that's called confirmation bias
 

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Perhaps one unintended advantage of the cx rays is their ability to cut / chop through small branches and twigs. I always use cx rays because I have had good luck with them and my experience has been that the bladed profile of the spoke is pretty good at handling small debris that gets into the spokes from time to time whereas a rounded profile may not work as well.
 

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Are Sapim CX-Ray spokes worth it over DT Comp/Revolutions? For a Carbon XC Wh...

I had a chance to ride same rim tire (blunt sl, karma) combination with dt and cx rays on the same course. I found the deflection to be less in a g outs and stiffness in corners to be much better with the wheel built using the cx rays. I changed the order I had already placed with revo to upgrade to cx rays. I highly recommend cx ray spokes for xc/light weight builds.
Despite the opinions of others (most of which have not ridden CX-Rays) I have had the same basic experience with CX-Rays. I would use them for all my wheels if I could afford them, which is not very often. Hard to justify 3.5X the cost.

CX-Rays are Lasers that have been forged (not rolled) into an ellipse blade shape. Forging does change the grain structure of the metal.
 

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CX-Rays are Lasers that have been forged (not rolled) into an ellipse blade shape. Forging does change the grain structure of the metal.
But the Laser/Revolution is also forged/coldworked, as are all spokes. It would be nice to see someone do an real stiffness test of each of a variety of spokes. Put a known tension on them and measure the deflection.
 

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Are Sapim CX-Ray spokes worth it over DT Comp/Revolutions? For a Carbon XC Wh...

But the Laser/Revolution is also forged/coldworked, as are all spokes. It would be nice to see someone do an real stiffness test of each of a variety of spokes. Put a known tension on them and measure the deflection.
Drawn, which is different than forging.

Sapim claims the CX-Ray has a center section strength of 1600 N/mm2, while the Laser is 1500 N/mm2.

Not an elasticity test, but it shows there is a difference in the spokes.

All else being equal, it is elasticity, not stiffness, of the spokes, that matters in the amount of lateral deflection in a tensioned wire wheel.
 

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Drawn, which is different than forging.
Both can be done at either "cold" or "hot" temperatures, and have a similar effect of realigning the grain structure of the metal.

Anyone know the exact processes DT/Sapim/etc use to produce spokes? Is it all cold processes, hot, a combo of both? Any heat treating done after forming the spokes?

Has any 3rd party actually done any strength/stiffness test on spokes? That would be some interesting data.

EDIT: Found this article, it's interesting: To the Point - DT Swiss Talks Spokes - Pinkbike

Contrary to popular belief, butted or bladed spokes are not "drawn" or stretched into their butted profiles by DT Swiss. Most people think the butted portion of the spoke is stretched into shape that is the finished product. This is not the case because it would leave the metal strained and weak. The butted spoke is actually is forged into its shape and while the process may seem similar, it isn't. The forging process allows the metal to be compressed into a denser package and this strengthens the metal by aligning the grain, giving rise to a part with improved strength characteristics.

...

Given that our aero spokes go through an extra forging process, they do gain some strength over their round cousins. Also, bladed spokes provide additional stiffness under braking and acceleration loads.
 

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Are Sapim CX-Ray spokes worth it over DT Comp/Revolutions? For a Carbon XC Wh...

Both can be done at either "cold" or "hot" temperatures, and have a similar effect of realigning the grain structure of the metal.

Anyone know the exact processes DT/Sapim/etc use to produce spokes? Is it all cold processes, hot, a combo of both? Any heat treating done after forming the spokes?

Has any 3rd party actually done any strength/stiffness test on spokes? That would be some interesting data.

EDIT: Found this article, it's interesting: To the Point - DT Swiss Talks Spokes - Pinkbike
Sapim has similar info on their site.
http://sapim.be
They do say the butted spokes are "drawn" with a cold forging process.
Sapim site said:
Sapim butted spokes have two major benefits: less weight and more strength! The SCFT-system (Sapim Cold Forging Technology) ’stretch‘ the spoke while retaining the linear molecular structure of the material, thereby increasing the spoke strength at the middle by at least 48%.
Stainless steel is drawn into the wire used for spokes.
Sapim use to have more info about the CX-Ray process. It broke the equipment if they tried to do more than one spoke at a time.
 

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Lots of the information here falls in that category except many have not tried both/several options available. i.e

This is the best bike ever....but I haven't tried anything else.

Having tried multiple options and like one over the other is call an informed opinion. Although it is based on subjective measurement like "feel".

Or maybe I do need to feel better about liking expensive spokes.;)
 

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Discussion Starter · #17 ·
Does anyone have side to side comparison with equal rims? I know the cross sectional area between Lasers and Cx Rays is the same, but does the further work and shape do anything to enhance the strength and stiffness, or is it all power of suggestion that makes them better?

Does anyone have side by side or any tests to prove?
 

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Do not confuse strength and stiffness.
Steels differs in strength a lot (tempering state, machining), but steel stiffness is pretty much a constant.

Look at matwebb.com the difference in elasticity modulus for a given steel (4130 for example) at different hardness: it's the same.

Look at difference in elasticity modulus between 4130 steel (chromo) and 431 (stainless): pretty much the same (205 vs 200GPa).
There is more variation between steels and stainless because of the nickel/chromium content, 316 stainless for example is 193GPa, but again, this is only 5%.
 

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Do not confuse stiffness with elasticity either.

Rather than just these generic property specs, would like to see the ratings of the alloys after they have gone through various forming/shaping/treatment processes. A part machined from a cast block is not going to perform the same as a cold forged part.
 

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Modulus of elasticity is "stiffness" for a material, but there are more mudules to consider. In reality only constructions and parts have a stiffness.

Also ausenitic stainless can only be hardened through cold working, and the harder it gets the more brittle it gets (toughness-resistance to impacts).

Cast material will always be lower strength due to microscopic faults I believe its about 20% or so weaker compared to forged. Btw all steels are forged already at the mill, except those that are cast or powedered, sintered and hip'ed.

I believe drawn spokes are actually "cold forged" but maybe not reduced as much?

Cold forging is usually only used on metals that are not heat treatable.

Work hardening - Wikipedia, the free encyclopedia
 
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