How to Put Sprockets on a Bike

Sprockets or "chainrings" are the front group of gears on a bicycle. There are three on mountain bikes, and either two or three on road bikes. New sprockets are often installed because the sprocket is damaged from rocks or bent from crashing. The sprockets attach to the crank arm from the outside and are easy change. You can remove the old ones and put new ones on using only one 4mm hex wrench.

Things You'll Need

  • 4mm hex wrench
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Instructions

    • 1

      Lean the bicycle up against a wall with the sprockets facing you. Pull the chain up and let it drop off the sprockets to the inside of the axle.There are four arms or "spider" arms that radiate out from the center of the crank arm where the crank enters the axle. On each one of the arms there is one setscrew that holds the sprockets to the crank.

    • 2

      Insert the 4mm hex wrench into the setscrews one at a time, loosen and remove them. Grab the sprockets on both sides with both hands and pull straight out. Pull the sprockets down the crank arm and off the pedal. The pedal will pass through the hole in the middle of the sprocket. Pull the setscrew out of the sprockets.

    • 3

      Lay the new sprockets together from smallest to biggest and insert the setscrew into the setscrew holes in the sprockets, it will pass through them, holding them together.

    • 4

      Hold the sprockets with both hands on either side, and insert the sprockets over the pedal. The pedal will pass through the hole in the sprockets. Pass the sprockets up the crank arm and into place on the crank arm spider. Spin the sprockets to align the setscrew holes in the sprockets with the holes in the spider.

    • 5

      Push on the setscrews, wiggle them around until they fit into the receiving holes on the radiating crank arms. Insert the 4mm hex wrench into each setscrew one at a time, and tighten securely. Pull the chain up, and drop it into place on the middle sprocket.