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Splined Crank Removal and Replacement

This type of crank attachment is found on many high-performance mountain bikes. Instead of a square hole that fits over the tapered spindle, the crank has slots around a round opening. The slots fit onto teeth that stick out from a hollow round spindle in the bottom bracket. This setup is easier to remove than the tapered spindle type, requiring only a hex wrench. (You don't need a special crank-pulling tool. If the crank won't come off after removing the cap bolt, you may have a tapered splined spindle, which DOES require a crank-pulling tool.)  Other crank types: standard female-threaded tapered spindle, male-threaded spindle with nut, tapered splined spindle.

Insert a hex-head wrench into the opening at the base of the crank. You use the same tool you'd use to remove the dust-cap screw from the crank on a standard tapered-spindle bottom bracket. Turn counter-clockwise until the bolt and dust-cap are loose. (The dust cap may keep the bolt from coming completely out of the crank -- you don't need to pull it out, you only need to loosen it.)

If you're working on the chainring side, take the chain off the rings and hang it on the outside of the bottom bracket. Slide the crank out away from the bottom bracket.

If you removed the crank to replace chainrings, do that now.

Inspect the spindle for damage, and check for side-to-side (left-to-right) motion of the spindle in the bottom bracket. Listen for grinding or rubbing as you turn the spindle. If the bottom bracket is bad, now's a good time to replace it.

If you're replacing the cranks (not simply removing it to replace a chain ring), place the new crank -- in the same position on the spindle as the old one. Apply Loctite to the threads of the retaining bolt and tighten it.

If you're replacing the crankset, you're now ready to thread the pedal into the crankarm.

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