How to choose a carbon road bike


Currently, if you want to buy a road bike, a certain part of what the market has to offer you is represented by carbon bikes. Quite affordable or rather expensive, heavier or lighter, produced by well known brands or by manufacturers raising their heads on the market, carbon road bikes represent the most advanced technology when it comes to bicycles. But, from so many models which one should you choose? To help you find an answer to this question we have prepared this guide to buying a carbon road bike.

Why carbon?

As we mentioned above, the vanguard of the bicycle industry is represented by carbon bikes. Although the first carbon frames appeared in the 90s, this technology has become accessible to more and more customers, and has been substantially improved only in the last few years. It should also be noted that at that time, carbon frames still did not manage to embed, at least not the way they do it now, their basic characteristics: strength, rigidity and light weight. A carbon frame can then be manufactured to provide rigidity right where this is needed and extra comfort for other areas. In addition, carbon fibers better absorb vibration.

A carbon bike is not cheap. Of course, we’re talking about quality carbon bikes, an issue that we intend to discuss in details in the next paragraphs. Such bike won’t turn you in the “super cyclist” you dream to be, but it will improve your performance to some extent and, most importantly, will offer you an absolutely unique pedaling experience. Few things compare to the feeling of riding on a carbon racer as this is something you must try at least once in life. All riding sensations, from speed up to comfort are amplified, and to put it in other words, satisfaction is on a much higher level when riding a carbon road bike.

Another thing you must have in mind is that a carbon racer, and we’re still talking about quality ones, is equipped with top of the range components, from wheels to seat and handlebar. In brief, such bikes really step out of the crowd!

Carbon Types

There are two types of carbon used in the bicycle manufacturing industry: unidirectional and woven. The difference is already visible, as for the first type of carbon fibers are oriented in one direction, while the other has fiber layers crossed  in several directions at various degrees (photo left). The biggest advantage of woven carbon is that a crack in one layer leaves the other unaffected. The only risk is the occurrence of cracks at other layers, but you can check it carefully inspecting the frame. Also, rigidity is another plus for this type of carbon.

Carbon can vary in strength. Thus, the least resistant carbon is low modulus, which can withstand a pressure of 240 kPa million, while the strongest is ultrahigh modulus, which can withstand pressures of up to 1 billion kPa. This means that ultrahigh modulus carbon fiber is 5 times stronger then steel.

Out of these types of carbon, 4 are currently used by bicycle manufacturers: unidirectional carbon (UD), modulus (M), high modulus (HM) and ultrahigh modulus (UHM).

Another aspect you must consider is carbon density, which is the number of filaments in a fiber, a value denoted by k. So, 1k carbon has 1,000 filaments/fiber, representing the minimum to be used in the industry. It is less durable, but lighter than, let’s take an example, 3,000 filaments 3k carbon. However, a frame made of 1k carbon may still be more resistant than 3k carbon if it combines several woven layers. Thus, the number of filaments is not necessarily a guarantee of carbon’s strength.

Another factor that you should keep in mind is how the frame was built. This is vital for the quality of the road bike and there are two options to consider when manufacturing a carbon frame: resin transfer moulding (RTM) and bonding (monocoque construction followed by bonding the frame’s tubes). The first method can be described in a nut shell as winding carbon fiber strips around a steel or aluminum frame. Option number two is basically casting carbon into a mold bearing the shape of various parts of the frame, while for RTM, tubes are sealed at their joints, same with non carbon frames. However, it must be said that for monocoque construction, the frame is not casted all in one piece, but rather in sections, such as the front triangle (headtube, top tube, down tube and seat tube) and the rear triangle. These two sections are then bond together, and this type of frame is often superior to the other two.

Carbon composite is another term often mentioned by carbon frames manufacturers.  This is not something unusual, as it only shows that carbon fiber layers have been intertwined with resin to obtain a better adhesion between them.

There are two characteristics to be observed in order to instantly recognize a carbon frame. It has no welding joints, as the frame is perfectly finished (as pictured right), and also a distinctive sound that you can hear if you knock your finger on it.  Also, if the frame has not been painted, you can see directly the texture of carbon tubes.

What carbon road bike should I choose?

As you could read above, carbon has a lot of coordinates and according to their values, it proves to be a better or worse option than other materials such as aluminum.

And now let’s get to the buying tips. From the start, we recommend woven carbon. The reason is that it is more resistant to impact than unidirectional carbon. It is also true that carbon has still some open road ahead until leaving steel or aluminum behind in terms of impact resistance. However, in case of failure, for woven carbon, tearing won’t be so violent to endanger you, as you will rather perceive it as a disfunction of the bicycle.

As for the different names associated with carbon, these are just different ways in which manufacturers try to differentiate themselves from the competition, and also give hints regarding the technologies they use. For example we have Trek’s OCLV frames and Cannondale’s BallisTec, but is worth saying that the relevant characteristics of the building process have been described above.

Focus your purchase on a bicycle coming from a well known brand and not on no-name producers! Besides their inherent value, frames coming from established brands are certain to have passed rigorous quality control. This has direct implications to your safety, as we previously mentioned that carbon has less impact resistance than aluminum, and, why not, to your pocket. Established brands offer warranty for their carbon frames and replace them in case of fault of construction.

The prices of carbon road bikes coming from a well known brand start around 1.200 euro, while for 1.500 you can already purchase a high-performance “machine”. Naturally, it all comes down to your budget and to your need, as the offer in this segment is quite rich.

Myths, gossip and rumors about carbon racers

Most often, carbon road bikes are criticized as being too expensive, too weak and most probably built in some Asian dark cellar. Let’s investigate these issues a little bit.

For sure, we could talk about their price all day long. Some find it extremely high, while others understand the situation as it is. Beyond doubts, to process carbon requires expensive technology, often borrowed from aeronautics. In fact, this is why only a few companies in the whole world produce the graphite used for carbon frames and other products. Another aspect of this discussion about price is the fact that as a carbon frame’s performance grows, so does the need for multiple technological processes and quality check procedures. In the end, it all translates into the final cost of the bike. Basically, the money you pay for a carbon bicycle also covers the skill of those who built it and the certainty that it was designed to safely provide the best performance, using the best materials. This is why we insist on saying that it’s best to buy a bike coming from an established brand. For sure, you don’t want your bargain bike’s frame to crack when you’re doing a nice 80 km/hours downhill!

And since I brought up the airline industry, a bicycle is much like an airplane when it comes to safety: you want to know everything about it and be sure it has been draconically tested before being approved for use.

The fact that they are made in Asia does not mean that carbon bikes are “traps” on two wheels. Most companies processing carbon are in China, Taiwan and Japan, and they are also the most famous at the same time. Toho Tenax, Toray and Mitsubishi Rayon Industrial are the top 3 names in the industry, responsible for 70% of the world production, and they are all are based in Japan. To sell their bicycles in Europe, all these manufacturers must test their products according to the European Commission for Standardization (CEN). There are warranty certificates that the frame and the rest of the components must receive and this is done through destructive testing, by independent specialized laboratories, approved by CEN.

Also, there is a total transparency for established brands bicycles, in terms of quality system, design process, material, and other important aspects.