OVERFAST Carbon Thru Axles for Specialized SL9 – Ultralight Road Disc Axle | 950kgf Strength

29±1g | Patented Carbon–Alloy Bond | >950kgf Tensile Strength

Ultralight carbon thru-axles with aluminium thread and titanium insert, designed for modern disc brake road bikes.

✔ Significant weight reduction
✔ EN & UCI tested
✔ 2024 updated version
✔ Complimentary worldwide shipping

Overfast axles suitable for other bike brands, please click here.

For Specialized Tarmac SL8/SL7/Venge/Crux/Aethos: Click Here

Engineering Highlights

Patented Carbon-Alloy Interface

The critical load-bearing interface between the carbon shaft and aluminium threaded section uses a patented mechanical bonding structure. This prevents separation under torque and tensile loads. Overfast also uses aerospace-grade adhesives to bond the two for added peace of mind. 

Titanium Insert

Titanium reinforcement for the hex wrench socket adds only 1g but significantly improves thread durability and long-term reliability.

Weight Savings

Saves ~100g compared to many stock thru-axles, depending on model.

Strength & Safety Testing

Each design passed both destructive and non-destructive testing, including:

• Fatigue test with wheelset (EN standards)
• Impact test with wheelset (UCI standards)
• Maximum torque test (19Nm)
• Tensile strength test (>950kgf)
• Lateral compression test (100–200kg)
• X-ray structural inspection
• Carbon cap impact & fatigue testing (20J impact, 12Nm repeated torque)
• 1+ year real-world athlete testing
• Threads are torqued to specification during QC inspection to ensure safety and fitment.

For a more detailed dive into the engineering, please see: 27g for a Pair: How OVERFAST Engineered the World's Lightest Thru-Axle

Assembly Information

• Do not use RSP assembly paste. It may cause thread seizure.
• Light marks on threads may be visible due to QC torque testing. Rest assured that all axles are brand new. This step is essential to guarantee the safety of the product.
• Ensure the head of the tool is inserted at least 15mm into the thru-axle before tightening/loosening.
• Use a torque wrench for installation. Recommended Torque: 7-9Nm
• Tighten by hand initially to ensure the thread between the thru-axle and frame is aligned to prevent stripped threads.
• Overfast uses a tighter thread tolerance, so please expect a tigher fit during assembly compared to stock axles.