Using this Marin Rift Zone Junior mountain bike is a breeze. Just hop on, pedal, and enjoy your ride. When you need to stop, simply squeeze the brake levers for a smooth halt. If you're a growing kid, you can adjust the air suspension to make the ride more comfortable. As for upgrades, you can change the 24 - inch wheels to 26 - inch ones when needed. When it comes to maintenance, keep the bike clean after each ride. Wipe off dirt and grime, especially from the brakes and gears. Check the tire pressure regularly to ensure a safe and smooth ride. And if you notice any parts wearing out, replace them as soon as possible.