How to Replace a Crankset

Bike cranks are the important components that connect your pedals to the chain and bottom bracket, converting your pedalling into the power that drives the rear wheel. The reasons for wanting to change your crankset could be to fit longer or shorter cranks, or maybe even add lighter cranks that are made from aluminium or carbon fibre. This handy video and How To guide will show you how to change a crankset like a pro!

  • 15mm pedal spanner
  • The correct size allen bolt for your bike
  • New Crankset
  • Torque wrench
  • A ratchet to undo crank bolts
  • Crank extractor
  • Grease
  • gloves for safety

Getting started

The first step is to get your chain onto the smallest cogs on the front and rear gears to create some slack. Then, it's time to get those pedals off. Just hold your 15mm pedal spanner on the connecting nut and keep the pedal from turning before running through the chain to loosen them off (anti-clockwise for the right side, clockwise for the right)

Getting your old cranks off

You'll need your Allen bolt now, which will need to match the bolt that connects your bike cranks to the bottom bracket. You can usually find this size in your bike's user manual, or you can try out the bolt for size if you've got an Allen bolt set. Simply loosen the bolt and take it off (you might find it easier to loosen it by hand once it's loose enough).

Then you'll need your crank extractor. Add plenty of grease to lubricate your crank extractor before inserting and tighten it with your spanner to prevent any damage to the threads. Once your crank extractor is nice and tight, give it a turn until it comes off the bike. Repeat on the other side.

Fitting your new crankset

After making sure your chain is hooked back onto the chain ring, you can now slide your new cranks into place. Start with the right crank and then the left, making sure they're in the '12 and 6' position. Then, replace the bolt and re-tighten them with your torque wrench until you hear a click - just check the newton meter matches the recommendation in your bike owner's manual beforehand.

The final step is to re-attach your pedals. Give the threads a good coating with grease (this will keep them turning and make it easier to get them off next time) and tighten them back up with your pedal spanner.

Well done, you're now a crankset changing expert!