Choosing the correct thru-axle size for your bike is crucial for safety and performance. A mismatch can lead to a wobbly wheel, a potential crash, and frustration. This guide provides practical steps on how to measure your thru-axle and understand the difference between 130mm and 135mm options.
Understanding Thru-Axle Dimensions: 130mm vs 135mm
The numbers 130mm and 135mm refer to the overall length of the thru-axle. This measurement is critical because it dictates the spacing between your bike's dropouts (the parts of the frame that hold the wheel). A simple mistake here can render your wheel incompatible with your bike's frame.
Key Differences:
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130mm Thru-Axle: Commonly found on modern mountain bikes and some road bikes, particularly those with boost spacing. Boost spacing generally uses wider hubs and thru-axles for increased stiffness and tire clearance.
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135mm Thru-Axle: A more traditional measurement, often seen on older mountain bikes and some road bikes. While still used, 135mm is gradually being replaced by 142mm and 148mm (boost) standards.
Ignoring the difference can result in:
- Wheel incompatibility: The wheel won't fit properly into the frame's dropouts.
- Safety hazard: A poorly fitted wheel can lead to instability and crashes.
- Frustration: Wasted time and effort trying to fit the wrong axle.
How to Measure Your Thru-Axle and Frame
Before buying a replacement, accurately measuring your existing thru-axle and frame is essential. Here's a step-by-step guide:
1. Identify Your Current Thru-Axle:
- Remove the wheel: Carefully remove your rear wheel from the bike.
- Inspect the axle: Examine the thru-axle itself. The length is typically printed on the axle, or you can find it in your bike's documentation.
2. Measure the Thru-Axle Directly (if unclear):
- Use a ruler or caliper: Measure the length of the thru-axle from end to end. Ensure the measurement is taken accurately.
3. Measure the Frame Spacing (as a double-check):
- Locate the dropouts: These are the two parts of the frame where the wheel sits.
- Measure the distance: Measure the distance between the center of each dropout. This provides a secondary confirmation of your thru-axle size.
Choosing the Right Thru-Axle: 130mm or 135mm?
Once you've accurately measured your thru-axle and frame, you should know if you have a 130mm or 135mm system. Remember to always check your bike's documentation or consult with a bicycle mechanic if you're unsure.
Important Considerations:
- Diameter: Besides length, also check the diameter of your thru-axle. Common sizes are 12mm and 15mm.
- Thread Pitch: The thread pattern on the axle is crucial for compatibility. If you need a replacement, ensure you get the correct thread pitch.
- Compatibility: Always ensure that the new thru-axle is compatible with your hub and frame.
Beyond the Measurement: Other Crucial Factors
While accurate measurement is key, several other factors influence thru-axle compatibility:
- Hub Spacing: This refers to the distance between the flanges of your wheel hub. The thru-axle length is directly related to the hub spacing.
- Thread Type: Thru-axles have different thread types (e.g., M12x1.0, M12x1.5). Using an incorrect thread can damage your frame or hub.
- Lever Type: Some thru-axles require specific lever types for tightening and releasing.
By following these steps and considerations, you'll ensure you choose the correct thru-axle for your bike, avoiding incompatibility issues and ensuring safe cycling. Remember to always prioritize safety and consult a professional if needed.
