Steel, aluminum, carbon fiber, and titanium. These are the most common materials used to make bicycle frames, both for road
and mountain
, gravel
or triathlon
. Most commonly, they are made of aluminum or carbon
. Or from a combination of both materials. There are also alloys that include chromium, vanadium, and there are even frames made from basalt fiber, which is a volcanic rock. But... which is better? People commonly tend to think that, between a bike with an aluminum frame and another with a carbon frame
, it is always preferable to choose the latter. However, this is not necessarily the case. Each material has its own peculiarities and offers a set of characteristics different from the others. That’s why, before letting yourself be seduced by aluminum, carbon, titanium, or any other raw material used for making frames, there are a series of factors you should consider:
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The type of use you are going to give the bike: What’s the point of spending €3,000 on a titanium bike if you’re only going to take it out a couple of times a month on flat sections of no more than 50 kilometers? It’s not the same to have a bike for racing, where the stiffness and lightness of the frame can make the difference of a few seconds more or less on the clock, as planning long routes on winding and irregular terrain that require greater flexibility and durability from the components.
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The weight: Many cyclists prefer a carbon bike over an aluminum one because the former’s frame weighs 300 grams less (in some models, even less). If the weight of your bike is a priority, maybe you should consider the option of buying lighter wheels instead of paying the price difference to swap an aluminum frame for a carbon one.
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The usage time: Are you going to buy a bike that will last you a lifetime or are you planning to change it within a year? Don’t forget that all materials experience wear and fatigue over time and with the intensity of use. But some wear out faster than others. Steel, for example, rusts more easily than aluminum, but its durability is also greater. Carbon fiber is more sensitive to major impacts, such as a fall onto rocks, but is less prone to wear from continuous use.
- The budget: It’s simple: with equal equipment and components, generally an aluminum bike costs more than a steel one, a carbon fiber one is more expensive than an aluminum one, and a titanium frame has higher manufacturing costs than the other three materials.
These factors are important when deciding on the frame material for our bike. To make the choice easier, we have prepared a simple guide with the characteristics of each material, their properties, and how they influence the handling of the bike.
Steel
Steel is considered an outdated material. In fact, the main brands stopped making steel frames for their mid-range and high-end lines years ago... and in most cases, also for their low-end lines. However, you can still find bicycles made of steel on the market. Until the 1970s, practically all bicycle frames were built from steel. In those years, mountain bikes appeared and, with them, the need for lighter materials. That’s how aluminum gradually began to be introduced into the cycling industry. In the 1990s, with the arrival of carbon fiber, steel was relegated to lower-end bicycles or white-label manufacturers. Nevertheless, there is a type of steel called CroMo that is still used as a material for frames of some high-end bikes. It is called this because it is made from an alloy of chromium and molybdenum. It is lighter and stronger than conventional steel. The main quality of steel bicycle frames is that they are cheaper, have greater durability than aluminum, and are easier to repair in case of dents or punctures. It is also a material with great strength. If you are going to carry a lot of weight, such as on a long adventure trip with dozens of kilos in your backpack and panniers, a steel bicycle can be a good choice. On the other hand, steel has the disadvantage of being heavier than other materials and is also more sensitive to rust.
Aluminum
Aluminum is currently the most widely used material for manufacturing bicycle frames. For frames, handlebars, cranks, seat posts, and various components. It was introduced to the cycling industry around the 1970s, and today all major bicycle brands have mostly aluminum models in their lineups. Unlike steel, aluminum is a material with very low density. In other words: aluminum is more malleable than steel and, in addition, it is lighter, making it an easier material to handle in the manufacturing of frames with different geometries. It is also cheaper than carbon fiber and requires less production time. Aluminum tubes can have different thicknesses. Manufacturers use this characteristic to create frames with an excellent combination of stiffness and lightness. For example, the ends of the top tube are usually thicker than the central part, thus enhancing the rigidity of the structure without increasing the weight. Another advantage of aluminum is its manufacturing cost, which is cheaper than carbon fiber. Moreover, it has excellent strength relative to how light it is and is less sensitive to corrosion than steel. On the other hand, it is a metal more prone to what is called material fatigue, which is structural wear due to the passage of time and intensive use. It is also a material more difficult to repair than steel. Aluminum frames are probably the best option in terms of budget and type of use for most cycling enthusiasts. However, even though brands use aluminum alloys with other metals to increase its strength, its durability is still less than that of carbon or titanium.
Carbon
Carbon fiber has become the star material of the cycling industry. Until 25 years ago, only a few professionals could enjoy bicycles with carbon fiber frames. Today they are part of the commercial catalog of most leading brands thanks to improvements in manufacturing processes, which have lowered their cost. It is a much more expensive material than aluminum and steel, but it can be adapted to practically any geometry. That is why in high-level competition there are more and more bikes with curved tubes or shapes that were impossible to manufacture just a few years ago... simply because the materials used had limited design capabilities. The great advantage of carbon fiber is its weight-to-stiffness ratio. It is a material that contracts and expands depending on the tension and the weight it has to absorb at any given time. That is why carbon bikes are more comfortable to pedal on irregular routes and long days on the road and off-road.
Another advantage is that it is a very lightweight material. Keep in mind that, although the frames are solid, they are actually made from fibers that in some cases are as thin as a human hair. These fibers are woven and reinforced with resin to create the frame structure. In addition, it does not have the corrosion problem that aluminum and steel face. And its durability is greater. That’s why some brands offer a lifetime warranty against material fatigue on their carbon frame models. You’re probably thinking that, since it’s a lighter material, has a longer lifespan, and is stiffer, it must also be better and worth paying the price difference to have a carbon fiber bike instead of an aluminum one.
However, you have to consider the downsides. Carbon is a fracturable material. That is, if a strong impact on an aluminum bike might cause a dent, on a carbon frame the material will directly fracture and in many cases is irreparable. The quality of a carbon fiber frame not only depends on the material, but especially on the manufacturing process. Depending on the thickness and placement of the fibers, the same frame can be more or less rigid and have certain points that are sensitive to breakage in the event of a sharp blow. Leading brands usually use the fiber cross-weaving technique to make their frames. For their top-of-the-line models, they use what is called a monocoque. This consists of a mold where the carbon is placed to create the triangle that forms the frame in a single piece. These molds are very expensive. That’s why monocoque bikes are not accessible to every budget. Carbon frame bikes make a notable difference for those who spend long days pedaling on the road, as they provide an extra degree of comfort and lightness. However, if you’re going to tackle technical trails, rugged paths, and routes of certain technical difficulty with your mountain bike
, you might want to consider whether it’s worth paying such a big price difference for a slightly lighter frame that could end up chipped if hit against a rock.
Titanium
When titanium made its appearance as a manufacturing material in the bicycle industry, it found itself sharing space with aluminum and carbon fiber. And, since the latter two were more affordable materials in economic terms, titanium bicycles were relegated to a very small portion of the market. Titanium is a material that shares properties with the other three mentioned above. It is as strong as steel, much lighter, resists corrosion better, and is much more durable. Practically, an optimally manufactured titanium bicycle is indestructible. We say 'optimally manufactured' because this is one of its major disadvantages, along with the price. Titanium is a component that hardly reacts with oxygen. That is why it is very difficult to weld the frame tubes and it must be done in chambers filled with argon gas. As for its advantages, the comfort when riding is more than notable given its combination of lightness and stiffness. And don't worry about the bike ending up crashing into a rock, because its ability to absorb impacts is superior. However, it is not cheap as a raw material nor is its manufacturing process simple. That is why the price of this type of bicycle is superior and many brands directly choose not to have models with titanium frames in their lineup.