How to Safely Remove the Chain from Your Mountain Bike
To take the chain off a mountain bike, first, shift the chain onto the smallest cog on the rear derailleur and the smallest chainring on the front derailleur. Then, using a chain tool, loosen the chain link pin and push it out to release the chain. The chain can then be removed from the bike. To reinstall the chain, simply reverse the steps and reattach the chain link pin with the chain tool.