How to Easily Change an Inner Tube on Your Mountain Bike
To change the inner tube of a mountain bike, first remove the wheel from the frame. Use tire levers to remove one side of the tire from the rim, and then carefully pull out the old inner tube. Check the tire and rim for any damage or debris that may have caused the flat, and remove if necessary. Insert the new inner tube into the tire and tuck it back into the rim. Carefully put the tire back on the rim and inflate the tire to the recommended pressure. Put the wheel back onto the bike frame and test the tire for any leaks.