FSA SELF EXTRACTING CRANK BOLT QR-31
The Tool-Free Solution for Crank Removal.
The FSA QR-31 Self-Extracting Crank Bolt is a specialized M27/M18 hardware kit designed to make the removal of FSA cranksets a seamless, single-tool process. In standard crank systems, you often need a separate "crank puller" tool to force the crank arm off the spindle. The QR-31 eliminates this need by integrating a "puller" cap directly into the crank arm. When you loosen the inner 8mm bolt, it backs out against the outer cap, effectively "pushing" the crank arm off the spindle as you turn.
Precision-machined from high-strength alloy and steel, the QR-31 is the factory-standard replacement for a wide range of FSA MegaExo and BB386EVO cranksets. It is a vital component for home mechanics who want to perform their own bottom bracket servicing or chainring swaps without the risk of stripping threads using old-fashioned hammer-and-punch methods.
How Self-Extraction Works
Integrated Puller Cap: The outer 27mm cap stays permanently threaded into the crank arm.
Internal M18 Bolt: The inner bolt threads into the spindle to hold the crank in place.
Mechanical Advantage: As you unscrew the inner bolt, it hits the underside of the outer cap. Continued turning uses that leverage to smoothly slide the crank arm off the splined spindle.
Zero Special Tools: You only need a standard 8mm Hex (Allen) key to both install and remove your cranks.
Key Features
High-Strength Steel Inner Bolt: Engineered to handle the high torque (38-41Nm) required to keep your cranks secure during aggressive out-of-the-saddle climbing.
Alloy Outer Cap: Features a sleek, anodised finish that sits flush with the crank arm for a clean, aerodynamic look.
Direct OEM Replacement: Specifically designed for FSA Carbon and Alloy road/MTB cranks that utilize the M18/M27 thread standard.
Corrosion Resistant: Built to withstand the road spray and grit encountered on long endurance rides or winter commutes.
Technical Specifications
| Feature | Specification |
| Model Number | QR-31 (390-2092) |
| Inner Bolt Thread | M18 |
| Outer Cap Thread | M27 |
| Required Tools | 8mm Hex (Inner) / 10mm Hex or Pin Spanner (Outer) |
| Torque Spec | 38 - 41 Nm (Inner Bolt) |
| Material | Alloy Cap / Steel Bolt |
✅ Why This IS For You
The DIY Mechanic: If you want to service your own bottom bracket at home without buying a dedicated crank puller tool.
FSA Crank Owners: Essential if you have lost or damaged your original bolt on an SL-K, K-Force, or Gossamer crankset.
Travel-Ready Cyclists: Ideal for riders who travel with their bikes; being able to remove a crank with just a multi-tool can be a lifesaver for packing bikes into travel boxes.
❌ Why This May NOT be for you
Shimano Hollowtech II Users: Shimano uses a different "pinch bolt" system; this FSA hardware will not fit any Shimano cranksets.
SRAM GXP/DUB Users: While SRAM uses a similar self-extracting concept, the thread diameters are different and are not cross-compatible with FSA.
BFC Pro Tip
The most common mistake with self-extracting bolts is removing the outer 27mm cap during maintenance.Don't do it! That cap must be tight for the self-extraction to work. If you try to loosen the inner bolt and the outer cap isn't there, the bolt will just come out and the crank will stay stuck. Before a big service, apply a small amount of high-quality waterproof grease to the underside of the outer cap—this reduces friction and makes the "pushing" action much smoother when you eventually need to take the cranks off!
