FSA M8 Crank Bolts
FSA

FSA M8 Crank Bolts

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Replacement M8 crank bolts from FSA made from Cr‑Mo chromoly steel — sold as a pair for square taper (JIS) bottom brackets. Durable, serviceable hardware for secure crank retention.

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Product Details

Overview & Technology

FSA M8 Crank Bolts (Part #390-2030) are precision replacement fasteners engineered for square taper (JIS) crank interfaces. Manufactured from Cr‑Mo (chromoly) steel, these bolts combine high tensile strength with proven fatigue resistance to keep your crank arms clamped reliably under road loads. The pair is finished and machined to fit standard M‑8 threaded crank holes used on many road and older mountain bike cranks. Because they’re genuine FSA hardware, you get consistent thread tolerances and the durability expected from OEM‑grade components—ideal for maintenance, rebuilds, or swapping cranks between bikes.

Key Features & Benefits

Durable material: Made from Cr‑Mo chromoly steel for a balance of toughness and long life, resisting stretching and wear common in cheaper bolts. That strength translates to secure clamping and fewer service intervals. Serviceable and straightforward: Sold as a pair and sized to standard M‑8 threads for quick replacement during bottom bracket overhauls or crank swaps. Using quality crank bolts reduces play and keeps chainline and shifting consistent.

Fit, Compatibility & Installation Notes

These bolts are specified for square taper (JIS) bottom brackets and cranksets using an M‑8 thread; they are compatible with most JIS-spec road and older MTB crank arms. Check your crank’s bolt bore and thread size before purchasing to confirm fit. Installation is straightforward: clean threads, apply light grease or an appropriate anti‑seize, thread the bolts by hand, and torque to factory recommendation for your crankset. If your crank uses a self‑extracting cap or a particular head style, verify the bolt head/profile matches your crank before installation.

Who These Bolts Are For

These M8 crank bolts are perfect for cyclists maintaining or restoring road and hybrid bikes with square taper cranks—mechanics, home‑wrenchers, and bike shops who need reliable replacement fasteners. They’re especially useful for riders working on older bikes, budget builds, or any setup that uses JIS square taper interfaces. If you want OEM compatibility without overpaying for aftermarket kits, these FSA bolts deliver dependable performance and peace of mind for everyday riding and long service life.

Key Features

  • ✓ M‑8 thread pitch specifically for JIS square taper cranksets
  • ✓ Made from Cr‑Mo (chromoly) steel for strength and fatigue resistance
  • ✓ Sold as a pair — ideal for one crankset installation or service
  • ✓ OEM FSA part number 390‑2030 / manufacturer part 400035
  • ✓ Precision machined threads for smooth engagement and secure clamp
  • ✓ Lightweight, low-profile replacement hardware for road use
  • ✓ Simple, serviceable bolt—perfect for routine maintenance

Specifications

Misc Pair

Product Identifiers

Vendor Item # 390-2030
UPC 400310004758

Frequently Asked Questions

Will these bolts fit my crankset?

These bolts fit crank arms designed for M‑8 threaded fasteners and square taper (JIS) bottom brackets. Verify your crank uses M‑8 thread and JIS taper; if it uses an ISIS, Octalink, or a proprietary interface, these bolts may not be compatible.

Do the bolts include washers or self‑extracting caps?

This FSA listing is for the crank bolt pair only. It does not include self‑extracting caps or separate washers. If your crank system requires a cap or washer, plan to reuse the originals or purchase the specific accessory separately.

Should I use grease or threadlocker on installation?

Use a light film of grease on the threads to prevent galling and ensure accurate torque readings. For applications prone to loosening (high vibration or long service intervals), a medium‑strength threadlocker may be used per your crank manufacturer's guidance.

How do I know when to replace my crank bolts?

Replace bolts if threads show wear, head or seating surfaces are rounded, or if you can no longer achieve correct clamping torque. Regular inspection during crank removal or bottom bracket service will catch wear before it affects performance.

Are these bolts heat‑treated or hardened?

FSA manufactures these bolts from Cr‑Mo chromoly steel and produces them to OEM tolerances for strength and durability. They are engineered to resist wear and provide secure crank retention under normal riding loads.

Buying Guide

When replacing crank bolts, match the thread size (M‑8), taper standard (JIS vs ISO), and head/profile to your crank. Material matters: chromoly (Cr‑Mo) bolts offer superior strength and fatigue resistance compared with basic steel hardware, making them a solid choice for road and commuting bikes. Buy bolts in pairs to maintain even clamping force across both sides, and keep a torque wrench and the crank manufacturer's torque spec handy during installation. If your crank uses special caps or self‑extracting hardware, confirm those components separately.

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