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One topic often discussed when choosing carbon wheels is spokes. In this article we’ll look at the pros and cons of carbon vs. steel spokes. I’ll share my experience testing over 15 different pairs of carbon wheels as well as insights from industry experts.
KEY TAKEAWAY
Carbon spokes are lighter and stiffer than steel spokes. Carbon-spoked wheels are usually less comfortable as more road vibration is transferred from the wheels to the frame and the body. Therefore, I don’t recommend them if you live in an area with bad roads or rough asphalt and don’t want to compensate for the stiffness with lower tire pressures. They are also more difficult to replace as they aren’t readily available, and you often need to contact the manufacturer to send a replacement spoke, which can take several weeks.
Steel spokes are the exact opposite. They are usually readily available, so sudden service is not a problem. However, they are heavier and less stiff, which leads to a higher overall weight of the wheels but better ride comfort.
Pros and Cons of Carbon vs. Steel Spokes
The following table summarizes the advantages and disadvantages of carbon vs. steel spokes. I will discuss them in more detail below.
| Pros | Cons | |
|---|---|---|
| Carbon spokes | • Lower weight • Higher stiffness • Better aerodynamics • Higher corrosion resistance | • Poorer ride comfort • Higher fragility • Higher price • More demanding repairs |
| Steel spokes | • Better ride comfort • Higher durability • Lower price • Easier repairs | • Higher weight • Lower stiffness • Poorer aerodynamics • Higher susceptibility to corrosion |
Weight
While the average steel spoke weighs about 5g, the average carbon spoke weighs 3g. The average steel-spoked wheel has 24+24 spokes. So, if we calculate the total weight of spokes for the popular Sapim CX-Ray (4.25g/pc), we get to about 204g. Carbon spoked-wheels usually need fewer spokes, e.g., 21+21, which gives us about 126 grams.
We are talking about a difference of about 80g per wheel or 160g per pair. That’s not exactly an insignificant difference. The less experienced probably won’t be able to tell, but you’ll notice the difference if you’re more sensitive.
Stiffness
Perhaps the biggest difference between carbon and steel spokes can be seen in their stiffness. Even though I weigh about 68 kg and am not the strongest cyclist, I can feel the higher stiffness of carbon-spoked wheels. I notice it most during accelerations and when sprinting. Less obvious is the behaviour of the wheels on descents, when they don’t feel as compliant, or on long rides (more on comfort later).
Unfortunately, I don’t yet have a way to quantify the stiffness of already built wheels, nor do I dare to estimate it in percentage terms. I can only describe my feelings. With carbon-spoked wheels, you feel like all the energy you put into the pedals is almost instantly redirected into forward motion.
In terms of tensile strength, steel spokes such as Sapim CX-Ray and Pillar Wing 21 have a tensile strength of approximately 280-290 MPa. In comparison, carbon spokes with a diameter of 2.3 mm have a tensile strength of between 480-600 MPa.
During stress tests, the metal parts of the carbon spokes (the nipple) separate from the spoke rather than the spoke itself breaking. The wide range of 480-600 MPa is due to differences in bonding and fixing methods used by different manufacturers.
On the other hand, steel spokes tend to break in the spoke itself. In stiffness tests, carbon spokes show 20-30% less deflection under the same load than steel spokes, indicating higher stiffness.
Riding Comfort
Regarding ride comfort, steel spokes are the clear winner here, as they can absorb ride vibrations better. You’ll appreciate this, especially on rough roads and long rides. When I tested the super-stiff Lún MEGA carbon-spoked wheels, I felt more fatigued than I did with regular wheels after riding for over 3 hours on bad roads. We just don’t have the conditions for such wheels here because, combined with the relatively higher pressures, they transmit basically all the vibrations to the bike and then to the body. This results in “vibration fatigue”.
So before buying, consider what roads you’ll be riding on, what parameters are important to you, and where you’ll be using the wheels most. Some people prefer comfort, others stiffness. Some people race, and some people ride for fun. Everyone’s needs are different, so take yours into account.
Aerodynamics
Some tests show that at high speeds (40 km/h or more), carbon-spoked wheels can reduce aerodynamic drag by 2-5 W compared to steel-spoked wheels. I found this claim from Up-Vine, a Chinese manufacturer of carbon wheels. Unfortunately, I don’t have the data or the reference point.
However, I found a test from FLO Cycling that looked at the difference between the Sapim CX-Ray and standard round spokes. And the result? Flattened spokes save 9 seconds per 40km. That may not seem like much, but you have to remember that the Sapim CX-Ray spokes are relatively narrow. At their widest point, they measure just 2.3mm. Carbon spokes are be 5mm or wider. The 9-second saving was also measured on one wheel, so on two wheels, the saving is 18 seconds. So we’re talking about a potential 84-second saving on an Ironman distance.
Durability and Maintenance
By durability, I mean mechanical and corrosion resistance. It can happen (especially in gravel and mountain biking) that a rock gets stuck in your spokes. It will probably bounce off in most cases, and nothing will happen. However, there are extreme cases where carbon spokes will be damaged because although they are much stronger in tensile strength than steel spokes, they are more fragile from side impact.
Corrosion can also be treacherous. I’ve had steel nipples corrode at the nipple/spoke connection of steel spokes, leading to failure and subsequent replacement. With carbon spokes, where the nipple is usually metallic, galvanic corrosion can occur. I have not personally encountered this yet, and the likelihood of it occurring is low but not zero. The risk is increased, especially when riding in rain or salty snow.
If you need to replace the carbon spoke, you may face availability issues unless you have a spare. They are not yet widespread enough to order online. It can take time to get a replacement directly from the manufacturer. Then the replacement itself is also somewhat more challenging, as you need to avoid twisting the spoke, which would lead to damage, and also ensure the correct (and usually higher) tension.
Price
For Chinese wheels, you will pay about 200-500 USD more for carbon spokes than for comparable wheels with steel spokes. For Western brands, you can multiply this amount by two, sometimes three. It very much depends; the question is whether these price differences are worth it.
Personally, I prefer wheels with carbon spokes that are not overpriced. Besides the handling characteristics, looks are also a significant factor for me. Carbon spokes tend to be wider, making the wheels look cooler. As they say, it’s not how you ride; it’s how you look, right?
Summary
So, what spokes should your new wheels have? Personally, I recommend those with steel spokes for more relaxed and longer rides, especially on rougher roads. You won’t be as fatigued by riding vibrations.
Carbon spokes are the way to go if you’re more performance-oriented, don’t want to waste precious watts, and are willing to sacrifice ride comfort.
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