Aero Bars: Performance Impact, Speed Gains, and Practical Considerations

How much of a difference do aero bars make?

Aero bars offer a significant aerodynamic advantage in cycling, primarily by reducing a rider's frontal area and optimizing their body position, leading to substantial speed gains or power savings, especially at higher speeds.

Understanding Aero Bars and Their Purpose

Aero bars, also known as time trial bars or triathlon bars, are an accessory designed to allow a cyclist to adopt a more aerodynamic body position. They typically consist of two extensions that project forward from the handlebars, often with armrests, enabling the rider to lean forward, support their upper body, and narrow their profile. The primary, overarching goal of aero bars is to minimize aerodynamic drag, which is the greatest impediment to speed in cycling on flat to rolling terrain.

The Science of Aerodynamics in Cycling

To understand the impact of aero bars, it's crucial to grasp the concept of aerodynamic drag. Air resistance is the force that opposes the motion of an object through the air. In cycling, it accounts for approximately 70-90% of the total resistance encountered by a rider at speeds above 15-20 mph (24-32 km/h). This drag is proportional to the square of the rider's speed, meaning a small increase in speed leads to a disproportionately larger increase in air resistance.

The drag force can be simplified by the formula: Drag = 0.5 * Air Density * Frontal Area * Coefficient of Drag * Velocity^2. Aero bars primarily work by reducing two key components:

• Frontal Area (A): By allowing the rider to tuck their head down, flatten their back, and bring their arms closer together, aero bars significantly decrease the amount of the rider's body directly exposed to the oncoming air.
• Coefficient of Drag (Cd): While less direct, the optimized body shape (more streamlined) can also slightly improve the Cd, although the reduction in frontal area is the more dominant factor.

The combination of reducing the frontal area and improving the rider's shape effectively lowers the overall Coefficient of Drag Area (CdA), which is the single most important metric for aerodynamic efficiency in cycling.

Quantifying the Difference: Speed and Power Savings

The difference aero bars make is not trivial; it's one of the most significant equipment advantages available to a cyclist.

• Speed Gains: For a rider maintaining a consistent power output, switching from a standard road position to an aggressive aero position can result in speed increases of 1 to 3 mph (1.6 to 4.8 km/h), particularly at speeds above 20 mph (32 km/h). For example, a cyclist averaging 20 mph in a road position might gain 1.5-2 mph, reaching 21.5-22 mph, with an optimized aero position.
• Power Savings: Alternatively, for a rider aiming to maintain a specific speed, aero bars can dramatically reduce the power required. Studies and real-world data suggest that an optimized aero position can save 10-20% of the power output required to maintain a given speed compared to a standard road position. This translates to significant wattage savings – for instance, a rider might save 30-50 watts at 25 mph (40 km/h). Over a long distance, these wattage savings allow a rider to either go faster for the same effort or sustain a given speed with less fatigue.
• Time Savings: In time trial scenarios, these gains accumulate rapidly. Over a 40-kilometer (25-mile) time trial, an aero position can easily save 2-5 minutes for a competitive cyclist, which is an enormous margin in races decided by seconds.

Factors Influencing the Benefit:

• Speed: The higher the speed, the greater the proportion of total resistance comes from air drag, and thus the more pronounced the benefit of aero bars.
• Rider Position: A poorly executed aero position (e.g., hunched shoulders, head too high) will yield less benefit than a well-optimized, flat-backed, head-tucked position.
• Course Profile: Aero bars are most effective on flat to rolling terrain. On steep climbs, where gravity is the dominant force, their benefit is negligible, and their added weight can even be a disadvantage.
• Equipment Integration: A fully integrated aerodynamic system (aero helmet, aero frame, aero wheels, skin suit, and aero bars) will yield greater benefits than aero bars alone.

Beyond Aerodynamics: Other Considerations

While aerodynamics is the primary driver, other factors influence the practical utility of aero bars.

• Comfort and Sustainment: An aggressive aero position, while fast, can be challenging to maintain for extended periods. Core strength, flexibility, and proper bike fit are crucial for comfort and the ability to sustain the position without undue strain on the neck, back, or shoulders. A comfortable aero position allows for maximal aerodynamic benefit over the entire race or ride.
• Handling and Safety: Riding in aero bars significantly alters bike handling. The hands are removed from the brake levers and shifters, and the rider's weight distribution shifts forward. This reduces steering control and makes quick reactions more difficult. Aero bars are generally not suitable for group riding, technical courses, or heavy traffic.
• Bike Fit and Adjustments: A professional bike fit is essential when adding aero bars. The entire bike setup (saddle position, handlebar height, reach) needs to be adjusted to optimize the aero position for power, comfort, and aerodynamics. A poor fit can negate aerodynamic gains, cause discomfort, or even lead to injury.
• Rules and Regulations: The use of aero bars is strictly regulated in many cycling disciplines. They are standard in time trials and triathlons but generally prohibited in mass-start road races (e.g., UCI World Tour events) due to safety concerns related to handling and braking. Always check the specific rules of your event or federation.

Who Benefits Most from Aero Bars?

Aero bars are particularly advantageous for:

• Time Trialists: Their specific design is optimized for individual efforts against the clock, where every second counts.
• Triathletes: Essential for the bike leg of triathlons, allowing for faster splits and preserving energy for the run.
• Long-Distance Solo Riders: Audax, ultra-endurance, or touring cyclists covering long distances alone can benefit from the reduced effort and alternative hand positions.
• Enthusiasts Seeking Marginal Gains: Any cyclist looking to maximize their speed and efficiency on flat to rolling terrain will find aero bars to be a potent tool.

Maximizing the Advantage: Proper Setup and Practice

Simply bolting aero bars onto a bike isn't enough to unlock their full potential.

• Professional Bike Fit: This is paramount. A good bike fitter will balance aerodynamics, power output, and comfort.
• Practice: Riding in the aero position requires practice to become comfortable and confident. Start on quiet roads and gradually increase your time in the aero position. Practice braking and transitioning in and out of the aero position.
• Core Strength: A strong core helps support the upper body in the aero position, reducing strain and allowing for a flatter, more aerodynamic back.
• Head Position: Learning to ride with a low, tucked head position while still maintaining awareness of the road ahead is a skill that significantly enhances aerodynamic benefit.

Conclusion: Are Aero Bars Worth It?

For the serious cyclist, triathlete, or time trialist, aero bars make an undeniable and substantial difference. They offer one of the most cost-effective and significant performance upgrades available, directly addressing the largest force opposing a cyclist's progress: aerodynamic drag. The quantitative gains in speed and power savings are significant, translating into minutes saved over typical race distances.

However, their benefit must be weighed against practical considerations such as bike handling, comfort, safety in group settings, and adherence to specific event regulations. When properly fitted, practiced, and used in appropriate scenarios, aero bars are an invaluable tool for maximizing speed and efficiency.