All About Thru Axles

All About Thru Axles

As a method of securing wheels to frames and forks, thru axles are superior in concept but muddled in execution by the inability of the bicycle industry to settle on a common standard.

All About Thru Axles

As a method of securing wheels to frames and forks, thru axles represent a superior concept in theory yet remain muddled in practice due to the inability of the bicycle industry to coalesce around a unified standard. Compared to traditional quick release skewers, thru axles can substantially augment the rigidity of the interface between the hub and the dropouts, while also precisely locating the hub to optimize the alignment between caliper and rotor on disc-equipped bicycles. However, the myriad of extant standards for axle diameter, thread pitch, dropout width, and differing conventions for front versus rear make specification highly complex. Unfortunately, the majority of bicycle manufacturers provide little to no detail on the thru axle standards utilized on their frames, leaving consumers without readily accessible compatibility data. When needing to replace a damaged or lost axle, or upgrade to a higher quality axle, this paucity of information engenders profound frustration. This article aims to elucidate some of the key variables to clarify the landscape.

The Universal Derailleur Hanger (UDH) embodies a significant step toward enhanced innovation and universality in mountain bike components. With its meticulously engineered 12 x 1.0 mm thread pitch to pair with diverse rear suspension topologies and hub spacing conventions, this component enables cross-frame interoperability and seamless integration. The patented design incorporates strategic technical features including a chain retention mechanism for derailleur security, and a rearward-pivoting failure point to safeguard both frame and drivetrain in crashes. Moreover, critical derailleur interface geometries have been harmonized with industry-standard mountain bike derailleurs to guarantee optimized shifting performance. For riders, this equates to simplified replacement and restored drivetrain functionality should damage occur. Rather than proprietary hangers dictating component compatibility, the UDH fit means facile swapping at any bicycle shop.

A Common Misconception: Despite the ubiquity of the DT Swiss brand on thru axle hardware, do not assume your axle adheres to a DT standard. More likely, your axle was manufactured by DT but designed around a different specification by the bicycle OEM.

The E-thru Conundrum: Shimano's "E-Thru" label encompasses several distinct variants with compatibility dependent on dropout width and threading conventions. For example, the standard 142 mm E-Thru axle may function in many 148 mm Boost E-thru frames, while proving too long for some 142 mm E-thru frames requiring shorter hardware. When replacing, precise length measurements from the existing E-Thru axle rather than assumed standards based on hub spacing offer definitive sizing data.

Sizing: Four key attributes determine appropriate thru axle specification:

  • Bolt Head Interface: Flat or conical
  • Total Length: The length of the axle, not including the head.
  • Thread Length: The length of the axle's threaded portion.
  • Thread pitch: Thread standard used on the axle, expressed as distance between threads in millimeters.

Fits: A list of known compatible forks or frames, by no means comprehensive.
Important Note: Minor variations within standards exist. Generally, any model of the same variant should function correctly barring outliers.




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