What is the best frame material for gravel riding? Aluminum vs. Steel vs. Carbon Fiber
Like their road and mountain bike cousins, gravel bikes can now be found in the three most common frame building materials: aluminum, steel and carbon fiber. There are seemingly never-ending debates in online cycling forums about the benefits and drawbacks of each frame material, let alone other materials like Titanium and frames that use mixed materials. Let’s have a look at what each of those three frame materials has to offer when it comes to gravel bikes.
Before the relatively recent advancements in composites materials manufacturing which made carbon fiber bikes more accessible, aluminum was the dominant material in the cycling industry. Aluminum has a very good strength to weight ratio, and the use of different aluminum alloys allows manufacturers to use tubing that best suits their frame building methods and bike design specifications. Additionally, Manufacturing technologies like hydroforming (the use of hydraulic pressure to shape metal alloy by pressing it into a die) allow bike manufacturers to manipulate tube shapes to optimize the weight and ride characteristics of their frames.
- Various alloys and modern manufacturing technologies can produce high-performance bike frames
- Relatively short fatigue life. Aluminum frames are also difficult to repair if cracked due to the difficulty of heat-treating outside large-scale manufacturing.
There is much truth in the oft-used phrase “steel is real”. Steel is abundant, tough and easy to manufacture. Like aluminum, it can be combined with other metals into alloys to suit various uses. Two renowned manufacturers of high-quality steel tubing used in bicycle manufacturing are Columbus and Reynolds. For gravel bikes, which are subject to more vibrations on rough terrain more than their road counterparts, the most important quality of a steel frame would be its excellent damping characteristics. Nowadays, the number of steel gravel bike offerings on the market is limited compared to aluminum and carbon fiber, with high-end tubing often only found on expensive custom-made framesets. Still, some very good steel gravel bikes are offered by several companies including All-City, Salsa and Niner.
- Great ride quality due to the superior vibration damping of steel.
- High ductility and less prone to cracking or breaking due to material fatigue compared to aluminum. Easier to repair if broken, too.
- Heavy except for the fanciest, thinnest and most expensive tubing.
- Susceptible to corrosion.
Carbon fiber has gained much ground in recent years in the bicycle industry. The material has an exceptional stiffness to weight ratio, enabling manufacturers to make bikes that are simultaneously very light and super strong and able to withstand the stresses of off-road riding. Moreover, manufacturers are able to use various carbon layups, or the direction in which each layer of carbon fibers are placed in relation to the layer below it, to manipulate the flex characteristics of the final component. An example of this is the thin chainstays with a flatter profile seen on many modern bikes, which arguably result in a smoother ride over uneven terrain.
- Can be used to make remarkably strong and light bikes.
- Very malleable and can be used to make complex frame shapes and optimize the flex properties of frame tubes.
- Not all carbon fiber is created equal, and it is often difficult for the average consumer to differentiate between good and mediocre carbon fiber construction.