When it comes to bicycle components, few decisions have the impact of choosing between thru axles and quick-release. These small but critical parts determine how your wheels connect to your bike frame, directly affecting performance, safety, and handling. Whether you’re a road cyclist, mountain biker, or casual rider, knowing the differences between these two systems can help you make an informed decision.
This article will explore the ins and outs of both thru axles and quick-release skewers, including their history, mechanics, advantages, and disadvantages, and what kind of rider would benefit most from each. We’ll also discuss the changing landscape of modern bike designs and how these systems fit into current trends.
The Evolution of Wheel Attachment Systems
Before diving into the technical details, it’s helpful to understand the evolution of bicycle wheel attachment systems. For decades, quick-release skewers were the dominant technology. Invented by Tullio Campagnolo in 1927, the quick-release skewer allowed cyclists to remove and replace wheels without the need for tools. This was revolutionary at the time, especially for competitive cyclists who needed to change wheels quickly during races.
The quick-release skewer became the industry standard and was ubiquitous in road bikes, mountain bikes, and even some commuter models for decades. However, as bikes evolved—particularly in terms of speed, terrain diversity, and technology—the limitations of the quick-release system started to become evident.
Enter the thru axle. First appearing in the mountain bike world around the early 2000s, thru axles were designed to address the shortcomings of quick-release skewers, particularly in terms of stiffness, strength, and stability. Over time, they have gained traction in road bikes, gravel bikes, and cyclocross as well. Today, many cyclists face the dilemma of which system is best suited for their needs. Let’s break down the key aspects of each.
Understanding the Mechanics
Quick Release
A quick-release consists of a thin metal rod that passes through the hub of the wheel. At one end is a lever, and at the other is a threaded nut. When the lever is closed, it tightens the skewer, securing the wheel to the bike’s dropouts (the slotted ends of the frame where the wheels attach). The system works by clamping the dropouts together, holding the wheel in place.
The primary appeal of the quick-release system is convenience. Riders can remove and replace their wheels in seconds without tools, which is especially useful for puncture repairs, transporting the bike, or switching wheels during races.
Thru Axles
Thru axles, on the other hand, are thicker, stronger rods that pass through the frame and the hub. Unlike quick-release, which simply clamp the wheel into place, a thru axle screws directly into the frame, creating a much more secure connection. Thru axles are typically threaded on one side and tightened using an Allen key or built-in lever, depending on the model.
The primary advantage of the thru axle system is its superior stiffness and strength. By eliminating the possibility of slippage or misalignment in the dropouts, thru axles provide a more solid connection between the frame and wheels. This is particularly important for mountain bikers and road cyclists who demand precise handling and maximum power transfer.
Key Differences Between Thru Axle and Quick Release
Stiffness and Stability
One of the most significant differences between thru axles and quick releases is the level of stiffness they provide. Because quick releases rely on clamping force to hold the wheel in place, there is a degree of flex, especially during hard cornering, sprints, or when riding rough terrain. This flex can affect handling and stability, particularly for heavier or more aggressive riders.
Thru axles, by contrast, are significantly stiffer. By threading directly into the frame, they eliminate flex in the dropouts, ensuring that the wheel stays perfectly aligned with the bike. This translates into better handling, especially at high speeds or when riding on challenging terrain. The additional stiffness is especially beneficial for mountain bikers who tackle rough trails or for road cyclists sprinting or descending at high speeds.
Safety and Security
Quick releases have been criticized for their potential safety risks. In some cases, riders may not fully tighten the skewer, leading to a loose or improperly secured wheel. While most quick releases are designed with safety mechanisms to prevent this (such as “lawyer lips” on the fork that make it harder for the wheel to accidentally come off), accidents can still happen, especially in high-pressure situations like racing.
Thru axles, on the other hand, offer a more secure attachment by threading directly into the frame. This makes it much less likely that the wheel will come loose, even under extreme conditions. The added security is one reason why thru axles have become the preferred standard for downhill mountain biking and gravel riding, where the stakes are higher if a wheel were to come loose.
Weight
When it comes to weight, quick-release skewers have the advantage. They are typically lighter than thru axles due to their simpler design and use of thinner materials. For weight-conscious riders, especially those in road racing, every gram counts. Quick-release systems are often favored by those looking to shave off as much weight as possible from their bikes.
That said, thru axles have become lighter over the years as manufacturers have refined their designs and materials. While thru axles may still be slightly heavier than quick-release skewers, the weight difference is not as substantial as it once was, especially when considering the performance benefits that thru axles offer.
Ease of Use
For riders who prioritize convenience, quick releases are hard to beat. The ability to remove and replace wheels without tools is a major advantage, especially for casual riders or those who frequently transport their bikes. Quick-release can be removed or adjusted in seconds, making them ideal for scenarios where speed and simplicity are critical.
Thru axles, on the other hand, require a tool (usually an Allen key or a built-in lever) for removal and installation. While this process is not particularly complicated, it is less convenient than a quick-release system, especially if you’re used to making adjustments on the fly.
Compatibility
Another important consideration is compatibility. Quick-release have been the standard for decades, meaning that many older frames and wheelsets are only compatible with this system. If you have an older bike or want to swap wheels between different bikes, quick-release may be the more versatile option.
Thru axles, however, are becoming increasingly common, especially in newer bike models. Most modern road, gravel, and mountain bikes are designed with thru axles in mind, particularly at the mid to high-end price points. If you’re buying a new bike, there’s a good chance it will come with thru axles, limiting your ability to use older quick-release wheels without additional adapters or modifications.
Performance
For performance-oriented riders, thru axles offer several benefits that can significantly enhance riding quality. The improved stiffness and security translate into better power transfer, more precise handling, and increased confidence when tackling technical terrain or descending at high speeds.
Quick releases, while convenient, do not offer the same level of performance. The potential for flex and misalignment can affect handling, especially under extreme conditions. However, for casual riders or those who primarily stick to smooth roads, the performance differences may be less noticeable.
(Source: pedalchile)
When Should You Choose Quick Release?
Quick-release remain a popular choice for certain types of riders. If your primary concerns are weight, convenience, and compatibility with existing components, quick releases may be the right choice for you.
Casual Riders: If you’re a recreational cyclist who sticks to smooth roads or bike paths, a quick-release system is likely sufficient for your needs. The convenience of tool-free wheel removal and the lightweight design make quick releases a great choice for leisurely rides.
Weight-Conscious Road Racers: For road cyclists who prioritize reducing the overall weight of their bike, quick releases offer a lighter option compared to thru axles. However, this weight advantage must be balanced against the potential loss of stiffness and performance.
Older Bikes or Multiple Bikes: If you have an older bike frame or want to use multiple wheelsets, quick releases offer greater compatibility. Most older bikes, especially road bikes, are designed around quick-release systems, making it easier to swap between different bikes or wheelsets.
Frequent Travelers: If you frequently transport your bike by car, train, or plane, quick releases are advantageous for quickly removing wheels and packing your bike. The simplicity and speed of the quick-release system can save valuable time when packing or unpacking your bike for trips.
Elitewheels’ Drive &Marvel Rim Brake Wheelsets are compatible with quick release.
When Should You Choose Thru Axles?
Thru axles are the preferred choice for riders who prioritize performance, safety, and handling. While they may be slightly heavier and less convenient to use, the benefits they provide in terms of stiffness and security make them the ideal choice for more demanding types of riding.
Mountain Bikers: For mountain bikers, particularly those riding technical trails, downhill, or enduro, thru axles offer superior stiffness and security. The added strength of the thru axle system prevents the wheel from moving or flexing under hard impacts, ensuring that the bike remains stable and predictable.
Gravel Riders and Cyclocross: For riders tackling rough gravel roads or cyclocross courses, thru axles provide the necessary stiffness and reliability to handle the challenging terrain. Thru axles ensure that the wheels remain aligned even when riding over uneven surfaces, improving handling and control.
High-Speed Road Cyclists: For road cyclists who enjoy sprinting, descending, or riding at high speeds, thru axles offer improved stability and power transfer. The added stiffness allows for more precise handling, especially in tight corners or when riding at speed.
E-Bikes and Heavier Riders: Heavier riders or those riding e-bikes may also benefit from the added strength and stiffness of thru axles. The additional weight and torque generated by e-bikes can put more strain on the wheel attachment system, making thru axles a safer and more reliable choice.
Elitewheels’ road & gravel Disc Brake Wheelsets are all compatible with thru axles. And its MTB Wheelsets are compatible for both quick release and thru axles.
Size Differences Between Thru Axles and Quick Releases
Quick Release Skewer Sizes
Quick-release skewers are generally thin and lightweight. They have a standard diameter of 5mm, making them compatible with most traditional bike frames and wheels. The length of the skewer varies depending on whether it is for the front or rear wheel. Front skewers typically measure around 100mm in length, while rear skewers are about 130mm for road bikes and 135mm for mountain bikes. These measurements correspond to the spacing of the bike’s dropouts—the slots in the frame where the wheel attaches.
Because of their relatively narrow diameter and length, quick-release skewers are lighter and allow for greater flexibility in terms of frame design. However, this smaller size also means that they offer less stiffness and security compared to thru axles.
Thru Axle Sizes
Thru axles are larger in diameter and length, contributing to their increased strength and stiffness. Unlike quick-release skewers, which are a uniform 5mm, thru axles come in a variety of diameters and lengths, depending on the type of bike and the specific model. The most common thru axle diameters are 12mm for road and gravel bikes and 15mm for mountain bikes, although there are other variations such as 20mm axles used in downhill mountain biking for even greater strength.
In terms of length, the standard sizes for thru axles vary based on the width of the bike’s hub. The most common sizes are:
100mm for the front axle of road and gravel bikes.
142mm or 148mm (Boost spacing) for the rear axle of road and gravel bikes.
110mm for the front axle of mountain bikes (often with 15mm diameter).
148mm for the rear axle of mountain bikes (Boost spacing).
The increased diameter and length of thru axles not only provide a more rigid connection between the frame and wheels but also contribute to their ability to handle the greater stresses of modern riding, particularly on rough terrain or during aggressive maneuvers. The larger size ensures that the wheels remain securely in place and aligned with the frame, reducing the risk of flex or misalignment, especially when tackling technical trails or rough roads.
The Future of Thru Axles and Quick Release
The cycling industry is constantly evolving, and while quick-release systems are still prevalent, the trend is moving toward thru axles, particularly in high-performance road and mountain bikes. Most new bikes, especially at the mid-to-high end of the market, now come equipped with thru axles as standard. As frames and wheelsets continue to advance, we may see quick-release systems become increasingly relegated to entry-level bikes or specific niche applications.
That said, quick releases are unlikely to disappear entirely. Their convenience, compatibility, and lightweight design will continue to appeal to certain riders, particularly those who don’t need the added performance benefits of thru axles.
Conclusion
Choosing between thru axles and quick-release skewers ultimately depends on your riding style, performance needs, and the type of bike you have. Both systems have their place in the cycling world. The key is to understand your own priorities and choose the system that best meets your needs. Whether you opt for the tried-and-true quick-release or the modern thru axle, you’ll be better equipped to enjoy the ride, knowing your wheels are securely attached to your bike.
