In recent years carbon fiber construction technologies have gained much ground in the bicycle industry. The material has an exceptional stiffness to weight ratio, enabling manufacturers to make bikes as well as components that are simultaneously very light and super strong, and able to withstand the demands of both road and off-road riding. Moreover, manufacturers are able to use different carbon layups, or the direction in which each layer of carbon fibers are placed in relation to the layer below it, to manipulate the characteristics of the final component.
Though there is still much room for improvement and refinement in carbon construction technologies, contemporary carbon fiber road and mountain bike wheels are more reliable than they have ever been. Many bike manufacturers are introducing carbon wheels as standard on their top end offering. Additionally, many carbon wheel manufacturer have introduced generously long warranties as well as crash replacement programmes on their carbon hoops. It is then no surprise that carbon fiber wheels are now a common sight at the trailhead and on the road.
While carbon components certainly have clear advantages and a certain allure, metal alloys have been around for much longer than composites, and as such the construction techniques are better established and easier to automate compared to the labor-intensive nature of carbon wheel manufacturing. Alloy rims are formed and welded very quickly. In comparison, it takes a multi-step process to make one carbon fiber rim. Due to this, and even with the decrease in the manufacturing costs of carbon fiber, aluminum alloy wheels are still cheaper by a significant margin.
When it comes to comparing bike component construction materials, things can get a little tricky and often polarizing. There are no clear-cut choices or recommendations here. Cycling is a diverse discipline and different materials can have their place in disparate riding applications. In this article, our intention is to look at the general characteristics of carbon and aluminum wheels and the factors that may encourage a rider to choose one over the other.
Aluminum wheels:
What’s great about aluminium wheels?
- Cost: Due to the aforementioned reasons, even the highest quality aluminium alloy wheels are almost always cheaper than their carbon counterparts.
- Ease of wheel-building and finding replacements: If your rides take you to locations where finding a well-stocked bike shop can be tricky, your chances of finding a replacement alloy rim are much higher than finding a carbon one. This is especially important if you intend to do, say, off-road or long-distance bikepacking.
- Better ride quality: Due to the material flex inherent in metal alloy, aluminium rims give a more compliant and comfortable ride than the often super stiff carbon rims.
- Easier to spot damage: Alloy has tell-tale signs before failure. Generally speaking you will be able to spot a dent in an alloy rim and be able to replace it before a more catastrophic failure happens. This is trickier to do with carbon.
What’s not so great about aluminum wheels?
- Weight: comparing like-for-like (wheel diameter, hub type, number of spokes, riding application, etc), aluminium wheels are heavier than their carbon equivalents.
- Flex: Alloy wheels tend to have more significant flex and they deform on impact. Compared to carbon wheels, alloy wheels tend to go out of true quicker.
- Corrosion: while rather rare with modern alloy rims, it can happen with wheels which see a lot of usage and infrequent maintenance and cleaning. Carbon does not corrode.
Carbon wheels:
What’s great about carbon wheels?
- Strength-to-weight ratio: on the bike, rotating weight matters more than other type of weight. Additionally, weight at the rim has a more significant effect than weight that is in a more central location, like the hub. Therefore, the weight savings between comparable aluminium and carbon wheels can be felt on the bike more than any other component swap. With lighter carbon fiber wheels, acceleration and power transfer is more immediate, and the bike just generally feels snappier.
- Stiffness: Carbon wheels are much stiffer than alloy ones at the same weight. This can be good or bad, depending on your own riding needs, but generally speaking stiffer wheels are always appreciated and sought after by performance-oriented riders, like racers. A stiffer wheel will make for sharper steering, a bike that is more responsive under acceleration and pedalling forces, better tracking when pushing the bike harder in corners and helps the rider maintain speed while expending less energy due to less of it being lost to material flex.
- Stays true for longer: carbon doesn’t bend as much as alloy, and as such (well-built) carbon wheels are less susceptible to going out of true quickly when used frequently on aggressive terrain.
- Looks: this is subjective of course, but the various surface finish techniques of carbon fiber construction can make for some really cool looking wheels.
What’s not so great about carbon wheels?
- Cost: Carbon wheels are still much more expensive than comparable alloy wheels.
- More difficult to spot impending failure: Carbon fiber is more susceptible to catastrophic failure because it does not exhibit signs of material fatigue as alloy does.
- Less comfortable: Due to the higher stiffness, carbon wheels offer a less comfortable ride than aluminium due to the lack of the flex inherent in alloy rims.
Conclusion: Should you go with carbon or aluminium wheels?
As with most comparisons: there is no absolute answer here. Many factors come into play including the riding application (casual riding vs performance cycling and racing), budget, longevity, etc. Racers will appreciate the weight savings and higher stiffness of carbon wheels, while casual riders, those on a budget and comfort chasers might want to go for aluminum alloy rims. One thing to keep in mind is that the rim material choice is only one component of many when it comes to bike wheels. A well-built wheel using cheaper material is usually better than a shoddily built one with fancier materials. Carbon construction technologies continue to improve and composite wheels are becoming more and more accessible, but alloy wheels are here to stay.
