How to Safely Remove the Back Tire on a Mountain Bike
To take the back tire off a mountain bike, first, shift the chain to the smallest cog on the rear cassette. Then, loosen the quick-release skewer or bolts on the back wheel. Lift the bike by the saddle or seat post and pull the wheel back and out of the dropouts. If the tire is difficult to remove, you may need to release the brake caliper or derailleur to provide some extra clearance. Once the rear tire is off, you can replace the tube or tire, or perform any necessary maintenance.