Bike-Axles
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Bike Axles: Everything you need to know?

“Bike Axles” is a vital part of the bicycle structure, which not only connects the wheel and the frame. but also directly affects the stability and performance of the ride. Bike Axles originated in the early 19th century when the bicycle structure was relatively simple. and the wheels were mostly made of wood and metal. It was not until the 1860s that Quick Release Axles began to appear and simplified the process of wheel removal and installation. At the beginning of the 20th century, with the continuous progress of bicycle design. the structure and material of the axle gradually diversified. No matter what kind of car you are, different types of axles have unique designs and applications.

This paper discusses the type, material, and size of bicycle axles, how to choose the right axle, and how to measure the size of a bicycle axle. And everything about Bike Axles to help you better understand this part, so that you can choose the right type of axle for your bike. Please dive with me!

Bike-Axles-1

What are bike axles?

The Bike Axles are an important part that connects the Bike wheel (650b Wheels) to the Bike Frames (or front forks). which are responsible for supporting the wheel and allowing it to rotate. It can be simply said that the Bike Axles is the core part of the bicycle wheel. because it ensures the smooth operation of the bicycle by fixing the position of the wheel set and transmitting force. The origin of Bike Axles can be traced back to Bike Axles. At the time, the earliest bicycles such as the “Boneshaker” and the “Penny Farthing” relied on a simple metal rod as the central axle of the wheel. which was used to hold the wheel and maintain the rotation function. With the advent of the chain drive system, bicycle design is gradually optimized. and higher requirements are put forward for the rigidity, durability and flexibility of the axle. Until the early 20th century, with the popularity of ball-bearing technology. Bike Axles gradually evolved into its modern form.

Bike Axles Function:

  • The Bike Axles stabilizes the wheels to prevent them from falling off or wobbling.
  • It allows the wheel to rotate freely, reducing friction resistance.
  • It has a transmission function, which transmits the trampling force through the wheel and pushes the bicycle forward.
  • It has good support to ensure that the wheels are running in the correct position.

Types of Bike Axles

Bike-Axle

There are many types of Bike Axles, you can choose the right axle according to the design and riding needs of Different types of Bikes. It mainly includes the following categories: Quick Release Axles, Thru Axles, Bolt-On Axles, and Solid Axles. These classifications can ensure the strength, ease of use, and compatibility of various types of axles used by some businesses in various scenarios of bicycles. Below I will describe the types and introduction of these bicycle axles:

Quick Release Axles:

quick-release-axles-1

Quick Release Axles, often abbreviated QR, are widely used for their ease of quickly installing and removing bicycle wheels. They consist of a fork that passes through the hub and is held in place by a lever and CAM mechanism. It quickly loosens the bar and lets you easily remove the wheel without any tools. It’s designed to be lightweight, and compatible with rim brakes and some older disc braking systems. But its security is relatively poor, not very strong.

The Quick Release Axles are beginner-friendly and easy to disassemble. But, compared with other axles, its stiffness is low, and he does not need other tools to open the lever, there are certain safety risks.

ParameterFront AxleRear Axle
Axle Diameter (Skewer)5 mm5 mm
Dropout Slot Width9 mm10 mm
Hub Spacing (Standard)100 mm130–135 mm
Thread PitchM5 x 0.8 mmM5 x 0.8 mm
Lever Length~12–14 cm~12–14 cm

Thru Axles:

thru-axles-2

The Thru Axles is a safe and sturdy bicycle axle, a modern axle designed for increased stability and rigidity. Unlike the Quick Release Axles, they are threaded and threaded through the hub and screwed directly into the frame or front fork for a tight, precise fit. It also has a larger diameter, with common sizes including 12×100 mm for road bikes and 15×110 mm for mountain bikes. The biggest advantage of Thru Axles is that it will enhance the bike’s handling. also prevent wheel bending, and improve the performance of the suspension and disc brakes. But, it is slightly heavier than the Quick Release system and requires tools such as an Allen wrench to install and remove. which is not as convenient as the Quick Release Axles.

It is often used in modern mountain, gravel, and high-end mountain bikes.

ParameterFront AxleRear Axle
Axle Diameter12 mm, 15 mm, 20 mm12 mm, 15 mm
Hub Spacing (Standard)100 mm, 110 mm (Boost)142 mm, 148 mm (Boost)
Thread DiameterM12, M15M12, M15
Thread Pitch1.0–1.75 mm1.0–1.75 mm
Axle Length (Overall)~120–180 mm~160–180 mm
MaterialAluminum, Steel, TitaniumAluminum, Steel, Titanium

Bolt-On Axles:

Bolt-on axles are generally secured with nuts on both axles. which provide a firm fit and are preferred primarily for their anti-theft and ruggedness. It is usually found on some city bikes, utility bikes, and some single-speed bikes, and has a strong anti-theft, durable, safe, and reliable. Because disassembly requires the use of tools, it is heavy use.

But, Bolt-On Axles are slower to disassemble and install than quick-release systems, requiring tools to operate. The length of the bolt shaft depends on the hub width and bicycle type, and the weight of the bolt fixed shaft depends on the material and length. In short, they all complement each other.

ParameterFront AxleRear Axle
Axle Diameter9 mm, 10 mm10 mm, 12 mm
Hub Spacing (Standard)100 mm130 mm, 135 mm
Thread DiameterM9, M10M10, M12
Thread Pitch1.0 mm, 1.5 mm1.0 mm, 1.5 mm
Axle Length (Overall)~120–180 mm~160–190 mm
MaterialSteel, Chromoly, StainlessSteel, Chromoly, Stainless

Solid Axles

Solid Axles is a traditional shaft design that is completely solid with no internal voids. There is only a single solid rod that passes through the hub and is secured by nuts on both sides. So, it is stronger and more durable than hollow shafts. Moreover, it has a simple and durable structure and low maintenance cost. which is very suitable for affordable and low-performance bicycles. But, it is heavier than modern axles, so it is suitable for BMX bikes, fat tires, or practical bicycles with heavy loads. And Solid Axles are not easy to break under extreme pressure, because the shaft is made of materials such as steel or chromium molybdenum. which has the toughness required to withstand harsh riding conditions and heavy blows, because of the solid. which is why it affects the weight of the bike itself.

ParameterFront AxleRear Axle
Axle Diameter9 mm, 10 mm10 mm, 12 mm
Hub Spacing (Standard)100 mm130 mm, 135 mm
Thread DiameterM9, M10M10, M12
Thread Pitch1.0 mm, 1.5 mm1.0 mm, 1.5 mm
Axle Length (Overall)~120–150 mm~150–180 mm
MaterialSteel, Chromoly, StainlessSteel, Chromoly, Stainless

Bike Axle Sizes

What you need to know is that different Bike Axle sizes will affect strength, weight, and many other reasons. Its diameter determines the bearing’s ability to withstand load and resist bending. and the length can ensure the correct fit with the wheel hub and frame to prevent mechanical problems. Below I will show you some common sizes:

Bike axle diameter

  • 9mm shaft (quick release): Weight is easy to use, and rigidity is poor compared to through shafts. Used for traditional quick-break road and mountain bike front axles.
  • 10 mm: provides slightly higher strength and stiffness for rear axles with quick-release systems for road bikes and mountains westwards.
  • 12 mm: It is the standard of modern bicycle axles and is more common in road and gravel bicycles. It provides a lightweight construction and enhances the balance between rigidity. enhancing wheel positioning and stability at high speeds.
  • 15mm: Generally used for the front axle of mountain bikes to provide better stiffness and load handling capacity for rough terrain. suitable for off-road riders and mountain cyclists.
  • 20 mm: Found on downhill and freeride bikes, it maximizes strength and stiffness for extreme impact. It offers heavy-duty options for intense off-roading.

Bike axle length

  • 110.0 mm
    Primarily used for older road bikes and mountain bikes with quick-release front axles, providing basic stability.
  • 137.0 mm
    A standard quick-release rear axle width for road bikes, widely used in traditional models for secure rear wheel integration.
  • 141.0 mm
    Found on modern quick-release rear axles, commonly used on road bikes and some gravel bikes, ensuring compatibility and stability between the frame and wheelset.
  • 146.0 mm
    A specialized width for certain mountain bike rear axles, offering additional width for better stability on rough terrain.
  • 155.0 mm
    Less common, typically used in specialized applications requiring slightly longer axles, such as custom or unique bike setups.
  • 158.0 mm
    Designed for bikes with wider rear hubs, such as certain mountain bikes and fat-tire bikes, accommodating broader frames and wheel setups.
  • 174.0 mm
    A standard width for rear thru-axles on fat-tire bikes, providing the extra width needed for wider frames in specific riding conditions.
  • 180.0 mm
    Used on larger mountain bikes, particularly downhill and freeride bikes, offering additional length for enhanced stability during extreme riding.
  • 187.0 mm
    The widest rear axle width, often seen on fat-tire bikes, is designed to fit the widest frames and hubs, ideal for extreme environments.

Bicycle shaft thread dimensions

The thread size of the bicycle axle is a key factor in ensuring compatibility with the nut or rear lower fork threads. allowing the axle to firmly hold the wheel. Different thread sizes are designed to meet different standards for different types of bikes and shaft designs. Here are some common bicycle shaft thread sizes:

  • 9mm × 1mm
    Commonly used for quick-release front axles, widely applied in road bikes and mountain bikes, offering lightweight construction and quick installation.
  • 10mm × 1mm
    A standard size for rear quick-release axles, with a larger diameter to provide extra strength, suitable for handling the higher load on the rear wheel.
  • 9.5mm × 24 tpi
    Designed for older models or specific professional bikes, this size features 24 threads per inch (tpi) to ensure compatibility with specific frames and wheelsets.
  • 9.5mm × 26 tpi
    Often found in classic bicycles or specialized applications, with a slightly adjusted thread pitch to meet unique installation requirements.
  • 10mm × 26 tpi
    A popular specification for rear axles, especially in mountain bikes. The finer threading ensures a secure fit, making it ideal for heavier loads and challenging terrain.

How to Measure Bike Axle Size?

Measuring the dimensions of the bicycle axle is a key step to ensure compatibility and proper installation. You need to know axle diameter, axle length, pitch, and thread length. Take the through shaft as an example, the following is the measurement method:

Before measuring, it is recommended that you check the mark on the axle first, many manufacturers will copy the size on the axle.

Tools needed

  • You need a metric ruler or a set of calipers
  • workbench
find-mark-1

Measurement Steps:

  1. Please use a ruler or caliper to measure the thickness of the shaft (outer diameter), your axle diameter is 12,15,20 mm. Generally, 15 and 20 mm are commonly used for enduro and DH front forks.
  2. Next, measure the shaft length. It does not include a head or washer, so only that part of the shaft length needs to be measured. But, the replacement shaft is generally 1 to 2 mm shorter or longer than the original shaft. in other words, if your shaft length is between these two sizes, it is recommended that you choose a longer thread.
  3. Next, you need to measure the pitch, which is the spacing of the threads. To determine the specific pitch, you can count the number of threads in a length range of 10 mm. For example, 10 threads correspond to a pitch of P1.0; If the number of threads is about 7, the pitch is P1.5 mm; When approaching 6 threads, the pitch is P1.75 mm. If there is any doubt during the measurement process. it is recommended to contact your frame manufacturer for more accurate support and information.
  4. The final step is to measure the length of the thread to ensure that the replacement axle thread length is the same or longer than the original. You now have all the key dimensions you need to order a replacement axle. To measure thread length accurately, measure from the starting position of the thread or the end of the axle, whichever is longer.

Bike Axles Material and Construction

Different materials of bicycle axles have significant differences in weight, rigidity, durability, tensile strength, and yield. and are suitable for different types of bicycles and riding needs.

  1. Steel Axles:
    • This material Bike Axles has high strength, strong durability and excellent deformation resistance. Neane carries high loads and is often used for urban commuter cars and weight-bearing bicycles. Because the Steel Axles material is relatively heavy, it is not suitable for lightweight riding scenes.
  2. Aluminum Axles:
    • The axle of this material is the right weight and rigidity, with the benefit of reducing the Bike Weigh. But if you use it for a long time, it is easy to damage, this Aluminum Axles is not durable as steel.
  3. Carbon Fiber Axles:
    • Carbon Fiber Axles is an ultra-light material with excellent shock absorption and rigidity. which is favored by the majority of cycling enthusiasts. Because it can improve riding efficiency, it is generally used on road bicycles and racing bicycles. because of its special material, it is expensive, but the impact may be more sensitive.
  4. Titanium Axles:
    • Titanium Axles pulls on each other between weight and strength, with a balanced benefit that is both durable and lightweight. It has strong corrosion resistance, higher cost, suitable for skilled riders, and is used on high-end mountain bikes and road bikes.
  5. Stainless Steel Axles:
    • The biggest advantage of Stainless Steel Axles is its high hardness, excellent rust resistance, suitable for off-road and rainy days. and its weight is between steel and aluminum shafts.
MaterialTensile Strength (MPa)Yield Strength (MPa)Features
Steel400–1,200250–900High strength, durable, suitable for heavy loads, but relatively heavy.
Aluminum Alloy200–600100–500Lightweight, lower strength than steel, widely used for road and MTB bikes.
Carbon Fiber1,500–5,000No yield pointExtremely high tensile strength, but limited impact resistance.
Titanium Alloy600–1,100450–900Balanced strength-to-weight ratio, corrosion-resistant, used in premium bikes.
Stainless Steel400–800200–600Excellent corrosion resistance, moderate weight, ideal for wet or rugged conditions.

Bike Axles Maintenance and Replacement

How to Maintain Bike Axles?

Before maintenance, you need to prepare the following tools, please see the list:

  • Chain wrench
  • Sprocket extractor
  • 15 or 17 mm taper wrench
  • Bearing grease
  • Small flat-head screwdriver
  • The pointed tweezers
  • A clean rag
  1. Remove the cassette flywheel and disc flywheel with the help of a chain wrench and sprocket puller.
  2. Remove the dust cover and loosen the locking nut, generally 12 and 17 mm.
  3. Remove the axle from inside the hub after removing the nut and lock the nut on the left.
  4. Then remove the ball bearing.
  5. Now, please use a quick rag to wipe all the removed parts: cone, hub cylinder, ball, center shaft, and dust cover.
  6. Then grease your hub and put the ball bearings back in place.
  7. Once all the bearing balls on both sides are in place, you can reinsert the center shaft from the right side. On the left, screw on the cone, nut, and lock nut.
  8. Finally, adjust the center shaft, replace the lock nut, and then check that the mounted parts are correct and do not move.

How do we determine the need to replace the Bike Axles?

If the following bearings are stuck or abnormal wear, and there is obvious bending or deformation. and abnormal noise when riding, or there are related problems such as thread damage. Then we need to replace the axle now, as for the replacement steps, please check the following content:

  • 1. Prepare appropriate tools such as an Allen wrench or wrench set and new compatible Bike Axles.
  • 2. Fix the bike to the maintenance rack, remove the wheel first, and then remove the axle.
  • 3. Before installing the new axle, thoroughly clean the hub and bearing parts, and check whether the bearings need to be replaced or greased.
  • 4. Install the new bicycle axle on the wheel according to the axle type and secure it.
  • 5. After installation and change, ensure that the wheel rotates smoothly and without shaking.

Compatibility with Bikes

Different types of frame and Bike axle compatibility

  1. Road bike:
    • Road bikes are suitable for quick axle removal (QR), the common size is 9mm QR or 12mm through axle at the front, 130mm QR or 12x142mm through axle at the rear. The Road Bike Frame has a narrow hub width with a focus on aerodynamics and weight reduction. So, it is necessary to be compatible with the newer model of the through shaft to enhance the rigidity.
  2. Mountain Biking:
    • Mountain bikes are suitable for barrel shafts because of their excellent rigidity and stability. Older models may use a solid shaft or a QR shaft. Common sizes are 15 or 20 mm at the front and 12x142mm, 12x148mm (Boost), or even 12x157mm (Super Boost) at the rear. Because the Mountain Bike Frame features a wider hub pitch to accommodate larger tires and disc brakes. The shaft diameter and hub type must be matched to ensure the best performance on off-road paths.
  3. Hybrid Bike:
    • Hybrid bikes generally use QR shafts, but some high-performance models may use through shafts for increased stiffness. Common front sizes are 9mm QR or 12mm through shaft. The rear dimensions are 135mm QR or 12x142mm through shaft. Hybrid cars combine the features of road bikes and mountain bikes, so the axle choice depends on your riding style.

Pros and Cons of Each Axle Type

1. Quick Release Axles

  • Advantages:
    • With lever design, no tool removal is required.
    • Often used on road bikes, lightweight.
    • Cheaper than Thru Axles.
  • Cons:
    • The fixed mode and diameter of the shaft are small, and the rigidity is low.
    • Not suitable for high-speed downhill or duplicated terrain use.
    • Poor security and anti-theft.

2. Thru Axles

  • Advantages:
    • The shaft runs through the wheelset and the frame and has a larger diameter and high stiffness.
    • Helps ensure accurate positioning of the disc brake and reduces brake friction.
    • Installation requires tools and strong anti-theft.
  • Cons:
    • It is heavier than the fast disable, which affects the lightweight demand.
    • Need bolts fixed, disassembly is not as convenient as the fast shaft.
    • The cost price is high.

3. Bolt-On Axles

  • Advantages:
    • Need tools to disassemble, high anti-theft.
    • Simple, cheap, and durable design.
    • Although not as good as the Thru Axles, your quick axles are stable and suitable for heavier loads.
  • Cons:
    • Each disassembly requires tools and takes a long time.
    • Low flexibility.

4. Solid Axles

  • Advantages:
    • The material is strong and durable, suitable for old bicycles and children’s bicycles, and can carry large loads.
    • Simple structure and low maintenance cost.
    • Solid Axles are heavier than other types of axles.
  • Cons:
    • Large weight and rigidity are generally not suitable for high-speed riding.
    • Installation is complicated.

Buying Guide: How to Choose the Right Bike Axles

Choosing the right bike axle is crucial to ensure a smooth and safe ride, which of course depends on your riding purpose, bike size, and budget. For racers or off-road riders, the through shaft provides excellent rigidity and stability. And quick axle removal provides convenience for daily commuting. Make sure the axle meets your bike frame and wheelset specifications, such as diameter, and length. and hub type, and consider disc brake compatibility for accurate alignment. Matching the axle to your bike’s needs ensures a safe and efficient ride.

Budget and quality are also key factors. Quick axle removal is affordable, while through-axle and bolt-on options are suitable for performance-conscious riders or commuters who need extra security. Trusted brands such as Shimano, SRAM, and DT Swiss offer durable and reliable axles, making them ideal for every riding need. Always invest in high-quality axles that match your bike and riding style.

Innovations in Bike Axles

As an avid cyclist, I’m always excited about innovations in bike technology. One of the most impressive developments is the Boost axle spacing concept. Increasing hub width and axle spacing enhances wheel stability and rear wheel stiffness. This is especially beneficial for mountain biking. where stability and handling are crucial on rugged terrains. I’ve tried a mountain bike equipped with Boost spacing, and the improved cornering. and obstacle navigation was immediately noticeable.

Another advancement that caught my attention is the improved design of thru axles with quick-release mechanisms. These offer faster installation and removal while maintaining the stiffness advantage of thru-axles. making them ideal for race environments where quick adjustments are key. I’m also intrigued by the special axle designs for electric bikes. With the added weight of motors and batteries. these axles are engineered to handle heavier loads while ensuring stable power transmission. These innovations make me feel that whether it’s for leisure rides or extreme challenges. choosing the right axle technology can significantly enhance safety and ride quality.

FAQ

Conclusion

In short, through this article quickly understood the Bike Axles function. and selection method is crucial to improving the riding experience. Whether you are riding professionally or for leisure, choosing the right axle not only ensures riding safety and comfort. but also improves fitness. With this guide, you should be able to determine more clearly what kind of bike axle you need and quickly choose the best configuration for your bike.

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