Sapim CX-Carbon fiber spokes for road bike wheels

The new Sapim CX-Carbon is billed as the stiffest and lightest aero spoke ever, and with a weight of just 3g each, they’re backing that up.

The construction is full carbon fiber until the very end, where there’s a bonded stainless CX-Ray threaded end that uses a standard nipple. So, they can be built to any rim, but for now they’ll have to be built with a specific new hub set from Edco. The Swiss wheel and component brand co-developed the spoke with Sapim and is featuring it on a very lightweight new wheelset we’ll cover separately.

Assuming other hub manufacturers come on board, aftermarket retail price will be around $16 per spoke when they come out in early March 2016. The first batch will be sent to builders they’re familiar with to get their feedback, but eventually they should make their way to the rest of us.

Sapim CX-Carbon fiber spokes for road bike wheels Sapim CX-Carbon fiber spokes for road bike wheels

The head of the spoke has a 4.5mm bulb that needs to be trapped inside the hub somehow, which is a common design used by Mavic and others. But the shape is unique, so the hub needs to be designed specifically for these spokes.

Sapim CX-Carbon fiber spokes for road bike wheels Sapim CX-Carbon fiber spokes for road bike wheels

It’s at least 25% lighter than their other spokes, which is the main benefit, but they’re also about 10% stronger, which means they can be built into a stronger wheel. They have virtually zero elongation, so you could use a very high tension, but they say it should be tensioned like a normal spoke so it doesn’t rip your rim apart. They also say it’ll make for a comparatively stiff wheel, so it’s designed for crits or climbing, not cruising all day fondos. For comparison:

CX-Carbon CX-Super CX-Ray
3.00g 4.11g 4.86g

Sapim CX-Carbon fiber spokes for road bike wheels

The spoke is 3.0mm round just above the head, then flattens to a 3.0×1.9 oval shape, then round again to 3.5mm diameter before the 14G threaded insert.

Sapim CX-Carbon fiber spokes for road bike wheels

Why? Because they could, and they want to remain at the top of the spoke industry in terms of technology and reputation. And hell, because it’s freakin’ cool.


  1. Hmm, now hope the hub is seriously lightweight too, you save only 1.3 gram compared to the cx-ray, so if the front hub, for example, is above 75 gram you will be spending your money wiser on a extremely lightweight hub.

    If sapim makes it an open standard, it could be verry interesting in the future

  2. Interesting …… and dreaming about a wheelset with these spokes, an Enve carbon hubset (I know, not compatible yet) ans some SES 2.2 rims…..

  3. But the aerodynamic – which really matters – most probably is worse than with the CX-Ray. Which has a cross-section of 2.3 x 0.9 mm making it considerably thinner and providing a better length-to-thickness-ratio than 3.0 x 1.9.

  4. “Virtually zero elongation” is not necessary a good thing. Spoke elongation under tension is a key component in the strength of a bicycle wheel. If there’s no elongation, the spokes will go slack when the wheel is loaded and the rim deforms ever so slightly. With slack spokes the wheel will be less stiff and is more prone to go out of true.

    Also, as already pointed out, oval-shaped steel spokes like CX-Ray have a clear aerodynamic advantage while the weight difference is minimal.

    In general, I wouldn’t be surprised if these go away just like DT Swiss titanium spokes did some years ago… In some applications good old steel can really be the best option.

  5. hmm, I saw something similar many years ago. I think it was in 1992.
    But those spokes had a metal insert on both ends of the carbon blade and could be used on any rim and hub.
    The only problem was, that they broke very easily when something hits them.

  6. Didn’t Mavic try this with the R-Sys wheels. To disastrous effects if I remember. There were all sorts of horror stories of the spokes shattering under hard braking and eventually the wheels were recalled and replaced with steel spokes.

    But sure, lets try this again.

  7. The threads are bonded onto the carbon. This seems sketchy. Im no engineer, but with such little contact area I feel it’d be under a ton of stress.

  8. Well, I’d like to see what happens when on of those inadvertent rocks is thrown into the wheel from one of your riding buddies.
    @Antti, great points on elongation.
    I’ll pass and stick with my dura-ace tubeless wheelset with steel spokes. Easily trued (when it’s needed which is rare).

  9. I’m not an engineer either, but I’ll take a guess at how the threads are connected. Ok, someone hold my beer, here it goes…

    The metal thread piece has an eye that the core sections of carbon nano-tubes are threaded through. So continuous strands of carbon start at the bulb, get looped through the eye, and end back at the bulb. Then the shaping fibers are layed over top of everything to make the aero shape and cover the looped core fibers and make the bulb at the other end. They spinkle it with some pixie dust and Old Bay and it’s done.

    There it is, sorry I figured out you junk Sapim.

  10. Still laughing reading this:

    –>“Virtually zero elongation” is not necessary a good thing. Spoke elongation under tension is a key component in the strength of a bicycle wheel. If there’s no elongation, the spokes will go slack when the wheel is loaded and the rim deforms ever so slightly. With slack spokes the wheel will be less stiff and is more prone to go out of true.<–

    Elongation =strength=stiffness=bread=jam=colour

  11. You’re confusing elongation and elasticity.
    Then again maybe Sapim are too?
    Language is a tricky thing as it is, it only gets worse when you have unintuitive terminology from the physical sciences being related by someone in their second language.

  12. Seems like an extremely high price for an extremely marginal gain and with a questionable reliability factor thrown in. I think I’ll let someone else guinea pig this one. The concept of composite spokes doesn’t bother me so much as the price for so little gain. Seems like a prime example of “just because you can doesn’t mean you should”

  13. @AJax: if steel is stronger than composites please explain why 30 years ago the Army gave up steel helmets in favor of composite helmets? Or why Formula 1 cars have become more survivable as they’ve increased the amount of composites used in their construction? Or any number of other examples that show your statement to be completely uninformed.

  14. Very cool. This is not for everyone and those that are complaining seem to always complain about everything.

    The other funny thing is the people that are posting on here that think they know more about spoke design and technology than SAPIN. Really. Because SAPIN I believe knows quite a bit about spokes.

  15. It’s like R-Sys NEVER! HAPPENED!

    I love Sapim’s spokes, but this is a really expensive solution for marginal gains – and if the Mavic experience holds here as well – with the possibility of exploding wheelsets.

  16. Stiffest maybe but not the lightest. The lightest aero spoke is the pillar extra light titanium which weigh approximately 2.5 grams per spoke.

  17. STS. If the shape is good then there is potentially good aero benefits.
    See a small steel framed bike versus a very fat carbon but better shaped one.
    There may even be useful cross wind stability benefits.

  18. The elongation is the property of the carbon fiber filaments to stretch, and in its case immediate failure upon exceeding the tensile strength. The issue in past was the inability to model all the forces experienced upon a wheel, which has become far better at today than in the past. Its also true that these CFP materials typically don’t have great impact resistance, but materials have been advancing so what had been a past failure could be successful today. Also, I would be curios to how it performs as the material is an-isotropic and presents a very different challenge in design. Have they made a layup design that would give similar modulus at any vector or used the bladed shape and designed for specific vectors.

    This will be a very rarely used solution for a lighter wheels (my guess it will be discontinued due to lack of interest). Also, lighter hubs often introduce lower bearing load capacities and reduced stiffness at the hub body, axle, and wheel. Only competitors at the very top levels going uphill would have any interest and would also require UCI changing the minimum weight rule to have any worthwhile gain. A very marginal one at that.

    I just would like to know if it actually works from an engineering exercise.

  19. LOL R-sys replaced with steel spokes? Love some good humor in the morning.

    Having owned two sets of R-Sys I can assure you they have not been replaced with steel spokes. Also steel spokes on a mavic? Ksyriums have always been Alloy. The spokes they issued after just have a kevlar strand inside. Those who have had problems have damaged the spoke.

    R-sys are sick and I am 250 lbs, never a moments worry with those things. Stiffer than shit. Light responsive wheels.

  20. OK Sapim, you thought you knew something about spokes, didn’t you? That was until you came here and you got taught…except you didn’t and still do so continue.

    Bottom line, I’m guessing Sapim knows a bit about spokes. Reputation and pride is important especially when people can say “I don’t like this, I’ll stick with your other excellent product”.

    What I say is, Sapim due to your other top products, I’ll give you the benefit of doubt, and the fact that you probably know more about spokes than most others here…probably 🙂 I’ll assume you didn’t just find some off cuts and try to make a few spokes without testing them first!

  21. Sapim knows their stuff. Pretty sure most people here who are proficient wheelbuilders know that the CX-ray is a great spoke to build with and the lazer is just as good. Also steel spokes on r-sys wheels is a laughable statement. These spokes and the way the r-sys spokes were set up and placed under tension (or lack thereof) are completely different systems.

    That being said, this will be big with the boutique cycling customer. I can imagine the guys over at Fairwheel are excited about these and the potential for ultra lightweight climbing wheelsets. Only a matter of time before tune/extralight/dash make hubs that are compatible with these spokes.

  22. ok …. the hubs are of course open source. we have several very good companies getting drawings and any help they need to make hubs. you will see hubs in the next couple months even before the spokes will be ready to ship to customers.
    price…. we are working dilligently on lowering the pricepoint and it is looking good so far, again more when the spokes are actually flowing out of the machines.
    rims, nothing special is needed, the spokes have a regular cxray thread part.
    works at sapim usa

  23. thor, how is the spoke durability from dropped chains and getting knocked around in the back of a car? Steel is very good at this. What keeps the embedded thread portion from turning in the spoke? It will be under a lot of stress during truing or wheel building at the high end of the tension. thanks.

  24. Guys, this is not a solution, it is another option for those that love forward thinking technology. If it’s not for you, it’s not for you. If it weren’t for companies like Sapim pushing the boundaries… where would we be today?

  25. Sapim is one of the biggest manufacturer of spokes and they have much experience in this market.
    So i think Sapim knows the requirements of spokes and they can handle the problems.
    Of course you will need a special hub but you will need also a special hub for straight pull spokes.
    I think other hub manufacturers like Tune will not dispense of wheels with this very light spokes for his Skyline wheels.

  26. While development is important, it shouldn’t be put ahead of safety and service life. If you need really light spokes Pillar Titanium are probably the lightest at the moment and would likely outlast carbon. I have used thousands of them and not many complaints.

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