Aero, Endurance and Superlight bicycles: here's the difference explain

Bicycles are becoming extremely specialized, with each manufacturer today having at least one different bike for every type of terrain and profile. There are no longer bikes that are good for any purpose. Instead, road bikes today are divided into three different categories based on certain conditions: superlight bikes suitable for climbing the toughest mountains, aerodynamic bikes ideal for high speeds, and endurance bikes for greater comfort. But that's not all; there's much more behind it! In this article, we've tried to simplify all the complexities of the world of road bikes to help you navigate better.

Aerodynamic Bicycles

Terrain: Generally flat courses where high speeds can be achieved. Features: More aggressive frame geometry, aerodynamic profile, high-profile wheels. Disadvantages: Comfort is sacrificed for speed, weight, difficulty handling in side winds.

Aggressive Geometry

The priority in producing aerodynamic bicycles is to reduce aerodynamic drag to be as "slippery" as possible. 85% of the resistance is given by the rider's body itself, so it makes sense to reduce the frontal profile as much as possible. The head tube of aero bikes, therefore, is very short to create a lower frontal profile and thus encounter less resistance. As a general rule, a head tube in an aero bike should be under 140mm, unlike an endurance bike which should be over 160mm. Along with the short head tube, aero bikes have a greater frame "reach" compared to endurance bikes. The "reach" is a specific horizontal measure from the center of the bottom bracket to the head tube. A high "reach" measurement and a short head tube mean that the cyclist will be more "stretched out" on the frame, reducing air friction. It's important to illustrate the difference between a frame's "reach" and a rider's "reach." The latter is measured from the tip of the saddle to the center of the handlebar. Unlike the frame's "reach," the rider's "reach" can be adjusted with a longer stem or a different saddle position. Adjusting the rider's "reach" can make their position on an endurance bike more similar to the position on an aero bike, and vice versa. Obviously, though, there are limits; the more you modify a position, moving away from the original, the further you move away from the bike's characteristics. Moreover, changing a cyclist's position too much could lead to musculoskeletal issues. Caution is advised. Having such an aggressive frame, on the other hand, can lead to some difficulties. Many cyclists do not have the flexibility required to reach the aerodynamic position of an aero bike or to remain in position for extended periods. The benefits of an aero, from the lower and more tucked position, are lost if you can't maintain the ideal position. Straining to hold such a position can sometimes lead to physical problems, for example, with the spine. The aerodynamic position puts a strain on a cyclist's neck.

Aerodynamics

The tubes of aero bicycles push the limits of UCI rules with a 3:1 profile; this means that every centimeter of depth can only correspond to 3 centimeters of length. The goal of an aero profile is to minimize aerodynamic resistance and be as "fluid" as possible in the wind. To achieve this, these frame tubes are long, thick, and tapered. The overall shape of an aero frame is angular and aggressive. The top tube is generally straight, unlike superlights and endurances which have a sloping top tube. With a straight tube, there is a shorter distance between the seat tube and the saddle itself, thus ensuring greater stiffness to the bike. This also reduces the bike's frontal profile. Endurance and superlight often have very long seat tubes to allow more flexibility and for greater comfort. The extra material needed for aero frames and their tubes adds weight to the bike. As a consequence, aero bikes are heavier than superlights even if they have more or less the same geometry and technical specifications. The components of aerodynamic bikes are obviously integrated into the frame. It can often be difficult to spot the brakes on an aero because they are hidden. Many bikes of this type have the rear brake hidden from the wind under the bottom bracket. It is rare to see cables on aero bikes as they are often hidden within the frame. Recently, the combination of stem and seamless tubes has become more common, not only to improve the bike's aerodynamics but also to increase the bike's stiffness. Completing the aerodynamics puzzle are the high-profile wheels. Aerodynamic bikes will always be equipped with high-profile wheels to reduce wind resistance and further improve aerodynamics. Normally, these wheels are at least 40 mm high, sometimes even 80mm. Additional weight and difficulty handling in strong and side wind conditions represent the downside of this choice.

Harder Gearing

This is not a universal feature of every aero bike, but it is more common here than on other types of bikes. They are frames built for speed, so it seems understandable that the gear ratios are less agile. Traditionally, road bikes are equipped with a standard 53/39 crankset. Many bikes are evolving to support a mid-compact 52/36 crankset. Obviously, the lighter and more agile the gear ratio (small in terms of metric development), the easier the gear is to pedal; which is perfect for reduced speeds uphill. Since aero are not designed for either of these purposes, often, they have a traditional 53/39 crankset to provide high speeds on the flat. The rear cassette ratio matches the need for speed. It is often equipped with an 11-25 cassette to allow for smoother shifting.

Superlight Bicycles

Terrain: Especially on routes with various climbs. However, they adapt a bit to everything. Features: Lightness and versatility. Disadvantages: It sits in the middle between the speed of an aerodynamic bike and the comfort of an endurance.

Lightness

As the name suggests, achieving the lowest possible weight is the goal of a superlight bicycle. Superlight bikes can weigh even less than 7 kg complete. UCI regulations impose that professionals not use bikes under 6.8 kg. It's a rule that perhaps should be updated, considering that carbon frames produced today can weigh much less than 700 grams. It was introduced in 2000 to prevent too much focus on weight at the expense of riders' safety. However, bikes sold to the public are not subject to these limits and today can weigh even less while still being very safe.

Versatility

Superlights are positioned in the middle between the features of a true aero and an endurance, making them the choice of many professional racers who aim for the general classification in a grand tour stage race. They are not as comfortable as endurances, but definitely more so than aerodynamics. Just as they are not as stiff as an aero, but are stiffer than an endurance. The reduced weight makes this type of bike more agile to handle than an aero. To achieve the most extreme lightness, traditional brakes must be mounted, however, we now find disc brakes even on superlight bikes. The tubes of a superlight are as thin as possible without excessively compromising strength and stiffness. Indeed, superlights always try to balance these two factors. Thinner tubes reduce weight and allow slight flexibility that reduces vibrations, making the ride more comfortable. To find the right balance between stiffness and weight, different types of carbon are used, sometimes layering it in certain points. A superlight might not be as stiff as an aero, but in relation to weight, it performs much better. The profiles of an aero are thicker and make it extremely resistant, but that extra material, along with other features, make it heavy. Superlights, on the other hand, offer similar resistance but cut away much of that extra weight.

Geometry

The geometry of a superlight tends to vary based on the manufacturer and its product line. Each manufacturer, indeed, mainly focuses on one type of road bike among those we are listing. Some brands might give their bikes, whatever type they are, a more aggressive cut because perhaps they own a much less angular endurance line as an alternative. Similarly, a manufacturer might choose to produce more comfortable bikes even when superlight, because they do not have high-range models. As already mentioned, superlights are the current choice for those who do all types of routes even daily. It is also for this reason that the geometry can vary a bit.

Endurance Bicycles

Terrain: Climb, flat, descent, it doesn't matter. What counts is comfort. Features: Comfort, durability, upright riding position. Disadvantages: Weight, less maneuverability.

Stability and Comfort

The purpose of an endurance is to be comfortable, robust, and durable. They were primarily created to face the Northern classics on cobbles such as Paris-Roubaix or the Tour of Flanders. These races, as the most passionate will know well, require going at high speeds even on the roughest roads. To try to reduce the stress that riders are subjected to with continuous vibration, endurances were created. They are bikes capable of better absorbing ground vibrations and mounting wider tires. Using wider wheels has many advantages, which is why there has been a gradual change of thinking in this direction. Wider wheels allow inflating the tires to a lower pressure compared to narrower wheels, thus reducing ground vibrations and allowing for smoother riding. Moreover, they also reduce rolling resistance and create inertia with their greater weight, a sort of flywheel effect. Most endurance bikes have a standard 28mm tire, in some cases even more.

Frame Geometry

In stark contrast to aerodynamic bicycles, endurances make the rider sit in a more vertical position. The head tube and the wheelbase are longer, the "reach" measurement is reduced, and the "stack" measurement is increased. This combination of factors allows for a less aggressive and more comfortable riding position, without straining the back, shoulders, neck, and tendons. The position, obviously, requires less flexibility, which is good, given that most of us struggle even to touch our toes. The wider frontal profile means it encounters more wind and greater resistance, but the comfort felt can make the ride smoother, the rider stronger, and, therefore, reach the same speed compared to a more aerodynamic but uncomfortable situation. Combined with the wider wheels, the longer wheelbase makes the bike more stable. Another element that increases the bike's stability is the wider handlebars; typically 44cm or 46cm, compared to 40-42cm of the aerodynamics and superlights. As the frame size increases, so does the handlebar size, because it is assumed that the rider is "larger." Regardless of the frame size, one can still expect the handlebar of an endurance to be on average 2 cm wider than any other size of its two competitors. The head tube angle of an endurance is also designed to make the riding sensation more relaxed.

Long-Distance Riding

As we've already said, endurances are built for those who pedal for many km. We've talked about the more comfortable frame geometry, but there are other features that allow the cyclist to pedal for a long time under any weather condition. Endurances are almost always set up with a compact crankset and a wide range of sprockets. This setup makes pedaling easy and ensures enough agility to overcome steep climbs even with tired legs. The sprocket pack is typically 11-28 or 11-32, and, when coupled with a compact 50/34 crankset, is sufficient to suit any type of cyclist. The use of disc brakes is a popular feature among endurance bicycles; they were the first to adopt disc brakes and then over time this technology also arrived at superlights and aeros. The type of riding for those who use an endurance makes disc brakes the best choice. Disc brakes outperform traditional brakes in every condition, offer greater braking power, and require less force to operate. Disc brakes also allow for mounting wider tires as manufacturers do not have to mount brake calipers.

Which to choose?

If you're flipping a coin to decide which of these bikes is more suitable for you, and you're not racers, comfort and durability should be a priority. The more relaxed frame geometry and the more robust nature of endurances should rank high on many people's personal rankings. If, on the other hand, you're thinking of racing, the two sides of the coin should only indicate aerodynamics and superlights. If uphill challenges are what you prefer, then the superlight is definitely your choice. For those who, on the other hand, love going fast on a circuit or on a Strava segment on the flat, for example, the most suitable choice should be an aerodynamic race bike. But the best option of all? Owning one of each model, of course!