FSA MegaExo Crank Bolt – Left Arm, 24 mm Alloy Cranks

The FSA MegaExo Crank Bolt ML038 is the original M17 bolt that fixes the left crank arm on the 24 mm spindle of FSA MegaExo alloy cranks such as the FSA Comet – a spare that turns a loose or damaged crank into a five-minute repair.

Why keep a spare crank bolt?

• A loose crank does damage. A lost, damaged or worn bolt lets the arm work loose – and that can ruin the spindle and the arm.
• Torque printed on the head. 38–41 N·m, so you always know how tight it should be.
• 10 mm hex key. Fits a standard 10 mm Allen key.
• Original FSA part. The same bolt that comes with the FSA Comet crank arm set in our shop.

Where does it go?

The crank bolt is part 5 – it threads into the end of the 24 mm spindle and holds the left crank arm (4).

1 – bottom bracket (two bearing cups threaded into the frame), 2 – wave spring washer, 3 – plastic spacer, 4 – left crank arm, 5 – crank bolt, 6 – drive-side crank arm with the 24 mm spindle, 7 – chainring or belt sprocket (direct mount).

When do you need it?

• The original bolt is damaged. Lost, cross-threaded or with a rounded tool socket.
• You rebuild a used crank. And want fresh hardware.
• You tour far from shops. A spare in the touring kit or the workshop drawer.

Specifications

Fitting

1. Clean the thread in the spindle and lightly grease the bolt thread.
2. Slide the left arm onto the spindle, with the wave spring washer in place.
3. Tighten the bolt with a 10 mm hex key to 38–41 N·m.
4. Check that the crank turns freely and has no side play.

Frequently asked questions

We build and service belt-drive and gear-hub bikes every day in our Budapest workshop. Not sure which part you need? Send us a photo of your crank and bottom bracket and we will tell you what fits.