Road bikes are classified based on specific parameters. Generally, we distinguish three main categories:
- Aero road bikes - ideal for those who can sustain high speeds;
- Endurance road bikes - perfect for maximum comfort.;
- superlight road bikes - best suited for climbing-heavy routes.
But there’s more to this classification than meets the eye, as bike manufacturers are becoming highly specialized. Nowadays, there are no longer models that work well for every "occasion." Instead, each brand offers at least one bike tailored to different types of terrain and riding profiles.
In this short guide, we’ve broken things down to help you quickly and easily understand the key differences between aero, endurance, and superlight bikes.
Aero Road Bikes
Ideal terrain: predominantly flat routes where maintaining high speed is crucial.
Key features: aggressive frame geometry, aerodynamic profile, deep-section wheels.
Disadvantages: reduced comfort in favor of speed, heavier weight, challenging to handle in crosswinds.
Aero road bikes are designed to minimize air resistance and be as "slippery" as possible. Since 85% of the total drag comes from the rider's body, the goal is to reduce the frontal profile as much as possible. This is why aero bikes have a very short head tube, creating a lower frontal position that encounters less wind resistance. As a general rule, the head tube length is typically under 140 mm, whereas endurance bikes usually have a head tube longer than 160 mm for a more upright and comfortable riding position.
Profile of an Aerodynamic Road Bike
Over the years, the ratio between the length and width of the frame tubes has always been pushed to the limits of UCI regulations. Since the goal of an aero profile is to minimize aerodynamic drag, manufacturers focus primarily on tube length and thickness when designing the frame.
The shape of an aero frame is sharp and aggressive. The top tube is generally straight, unlike lightweight and endurance bikes, which feature a sloping top tube. This design reduces the distance between the seat tube and the saddle, increasing the bike’s stiffness while also minimizing the frontal profile.
All the additional material required for a frame (aero in this case) increases the bike’s weight. That’s why aero bikes tend to be heavier than lightweight models, even though they share similar geometries and technical specifications. Additionally, the components of aero bikes are often integrated into the frame. One example is the rear brake, which is hidden from the wind and positioned under the bottom bracket. Recently, the combination of seamless joints and tube shapes has become more common—not only to enhance aerodynamics but also to improve the bike's overall stiffness.
Deep-Section Wheels
Deep-section wheels complete the profile of an aero bike, as they are essential for reducing wind resistance and further enhancing aerodynamics. Typically, their rim depth starts at 40 mm and can go up to 80 mm. However, the added weight and the challenges of handling in strong crosswinds are the trade-offs.
Frame Reach vs. Rider Reach
Aero bikes also have a longer frame reach compared to endurance bikes. A greater reach combined with a short head tube positions the rider in a more stretched-out posture, reducing air resistance. However, it's important to distinguish between frame reach and rider reach. Rider reach is measured from the tip of the saddle to the center of the handlebar and can be adjusted by changing the stem length or modifying the saddle position.
Can a Cyclist's Reach Be Adjusted?
Adjusting a cyclist's reach can make their position on an aero bike resemble that of an endurance bike, and vice versa. However, there are limitations—deviating too much from the original position can compromise the bike’s intended characteristics.
Additionally, excessive modifications to a cyclist’s position can lead to musculoskeletal issues, so adjustments should be made with caution. On the other hand, an aggressive frame geometry can present challenges, especially for riders lacking the flexibility to sustain an aerodynamic position for extended periods. The benefits of an aero bike can diminish if a rider cannot maintain the required posture. Forcing oneself into an aggressive aero position may lead to physical issues, particularly in the spine. This is because the aero position places significant strain on a cyclist’s cervical spine.
Gear Ratios
Road bikes are typically equipped with a standard 53-39 crankset, although there is a growing trend toward mid-compact 52-36 setups. Naturally, the lighter and more agile the gear ratio (smaller in terms of gear inches), the easier it is to pedal—an ideal condition for climbing.
However, since aero bikes are designed for speed, they often feature a traditional 53-39 crankset, paired with a rear cassette (usually 11-25) that aligns with the need for high velocity and ensures smoother shifting. As a result, it’s understandable that aero bike gear ratios are generally less forgiving when it comes to climbing.
Bianchi Oltre RC 2025 aero road bike
Endurance Road Bikes
Ideal terrain: climbing, flats, descents—it doesn’t matter. What counts is comfort.
Key features: comfort, durability, upright riding position.
Disadvantages: heavier weight, less maneuverability.
Endurance road bikes are built to be comfortable, robust, and long-lasting. Primarily designed to tackle the cobbled roads of Northern Classics like Paris-Roubaix and the Tour of Flanders—races that demand high speeds even on rough terrain—this type of bike reduces rider fatigue by absorbing road vibrations more effectively. This is also thanks to wider tires, which allow for lower air pressure compared to narrower ones, resulting in a smoother ride. Additionally, endurance road bikes minimize rolling resistance and, due to their heavier weight, generate a flywheel effect that helps maintain momentum over long distances.
Profile of an Endurance Road Bike
In stark contrast to aero bikes, the profile of an endurance road bike places the rider in a more "upright" position. The head tube and wheelbase are longer, the reach is shorter, and the stack height is greater. This combination allows for a less aggressive and more comfortable riding posture, reducing strain on the back, shoulders, neck, and tendons—requiring less flexibility. That’s a good thing, considering most cyclists struggle to even touch their toes.
The front profile is wider, which increases wind resistance, but the added comfort makes pedaling easier. A strong rider can still reach the same speeds as someone in a more aerodynamic (and less comfortable) position.
Wider Wheels and Handlebars
Most endurance bikes come with standard 28mm tires, though some models feature even wider options. Combined with wider wheels and a longer wheelbase, this setup enhances the bike’s stability. Another factor contributing to this stability is the wider handlebars, typically measuring 44 cm or 46 cm compared to the 40/42 cm found on aero and lightweight bikes.
As the frame size increases, the handlebar width also grows in proportion to the rider’s height. Regardless of the frame size, an endurance bike’s handlebars are, on average, 2 cm wider than those of an aero or lightweight bike of the same size. Additionally, the head tube angle on an endurance bike is designed to create a more relaxed and stable riding experience.
Gear Usage and Brake Type
Beyond the more comfortable frame geometry, endurance bikes have additional features that enhance the rider's position, allowing for longer rides in any weather condition. These bikes are almost always equipped with a compact crankset and a wide-range cassette (11-28 or 11-32), making pedaling easier and ensuring enough agility to tackle steep climbs even when fatigue sets in. When paired with a 50-34 compact crankset, this setup provides a versatile solution suitable for cyclists of all levels.
Disc brakes are the most common choice for endurance bikes, which were among the first to adopt this braking system due to their specific riding style. Over time, disc brake technology has also been incorporated into aero and lightweight models. Disc brakes outperform traditional rim brakes in all conditions, offering greater stopping power and requiring less force to engage. Additionally, they allow for wider tires since manufacturers don’t need to accommodate caliper brakes.
BMC Roadmachine 01 FOUR 2024 Endurance road bike
Superlight road bikes
Ideal terrain: all types, especially routes with significant elevation gain.
Key features: lightweight and versatile.
Disadvantages: a balance between the speed of an aero bike and the comfort of an endurance bike.
Superlight road bikes are designed to achieve the lowest possible weight. These models can weigh as little as 7 kg or even less. According to UCI regulations, professional cyclists cannot use bikes weighing under 6.8 kg—a rule introduced in 2000 to prevent excessive focus on weight at the expense of rider safety. However, this regulation might be outdated, considering that modern carbon frames can weigh well below 700 grams while still ensuring structural integrity and safety.
Profile of an Superlight Road Bike
Superlight road bikes are a hybrid between aero and endurance bikes, which is why they are the preferred choice for many pro riders aiming for the general classification in a Grand Tour. While not as comfortable as endurance bikes, they are certainly more forgiving than aero models and stiffer than endurance frames.
Their reduced weight makes them easier to handle compared to aero bikes. Additionally, while achieving extreme lightness often required traditional rim brakes in the past, disc brakes are now increasingly common even on superlight road bikes.
A Balance Between Stiffness and Weight
The tubes of a superlight frame are very thin without compromising strength and stiffness, always maintaining a balance between these two factors. Thinner tubes reduce weight and allow for slight flexibility, which in turn absorbs vibrations and makes pedaling more comfortable.
To achieve the perfect balance between stiffness and weight, different types of carbon fiber are used, often layered in certain areas. A superlight bike may not be as stiff as an aero bike, but when considering the weight-to-stiffness ratio, it performs much better. Aero bike profiles are thicker, making them extremely resistant, but the extra material, along with other features, adds weight. Superlight bikes, on the other hand, offer similar strength without carrying all that extra weight.
Geometry of a Superlight Frame
The geometry of a superlight frame tends to vary depending on the manufacturer and its product line. Each brand primarily focuses on developing a specific type of road bike. However, some manufacturers may give a more aggressive design to any model in their collection, especially if they also offer a much more relaxed endurance line as an alternative.
Similarly, a brand that doesn't produce high-end models might choose to design more comfortable superlight bikes. As mentioned earlier, ultra-light road bikes are the go-to choice for riders tackling all kinds of terrain, even on a daily basis. This is why their geometry can vary slightly.
Specialized S-Works Aethos 2023 Superlight road bike
Aero, Endurance, or Superlight Bikes: Which One to Choose?
We've reached the end of this long and (hopefully) comprehensive guide to choosing between an aero, endurance, or superlight road bike. Now you have all the tools to safely purchase a bike online without the risk of disappointment. So, here's a final quick recap:
- if you're not a professional or an advanced amateur, endurance road bikes are the best solution, as they provide comfort and durability.;
- if you love competition and can't stay away from racing, an aero road bike or a superlight bike (if you also enjoy challenging climbs) might be the right fit for you.:
- are you a natural-born sprinter, or do you always chase KOMs on the flats in Strava? Then the aero bike is your best choice.;
- the best option of all? Head to bike-room.com and get one of each!
