How to Change a Crankset

The cranks are the arms on the bicycle where the pedals attach. As the cyclist pedals, they turn the chain to power the bike. Cranksets have varying lengths, typically from 170mm to 174mm. Changing out the crankset requires removing them and the chainrings. Chainrings are the large, toothed gears on the center of the bicycle that provide one part of the gear ratio for the bicycle's speeds.

Things You'll Need

  • 8mm Allen wrenches
  • 5mm Allen wrench
  • Crank extractor tool
  • Bicycle work stand
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Instructions

    • 1

      Place the bicycle into the work stand. Pull the chain off the front chainrings and let it hang off the rear wheel.

    • 2

      Insert the 8mm Allen wrench into the center hex screw on both sides of the cranks. Unscrew the hex screws. Insert the crank extractor tool by pushing it into the crank's center and giving a half-turn clockwise. Go as deep into the center where the screw was removed as possible. Place the extractor arm into the extractor and turn counterclockwise to pull the cranks off the bike. If you are changing the cranks out to a new set that uses a different spindle than the one in the bicycle, use the bottom bracket tool to remove the bottom bracket with the spindle. Insert the new bottom bracket and spindle with the bottom bracket tool.

    • 3

      Unscrew the chainrings off the right-hand side crank arm using the 5mm Allen wrench. Screw the chainrings onto the new right-side cranks using the 5mm wrench.

    • 4

      Place the cranks onto the bicycle's bottom bracket spindle. Keep the cranks at a 180 degree angle to each other (one pointing down and the other up). Tighten the cranks into the bottom bracket using the hex screws and the 8mm wrenches. Turn as tight as possible. Place any screw caps over the end of the screws.

    • 5

      Bring the chain back up and onto the chainrings.