In simple terms, a vehicle’s transmission makes it so that a single rotation of the engine’s camshaft leads to more than a single rotation of the wheels. Gears on a bicycle work the same way. In higher gears, your legs can pump at the same rate, while the wheels turn quicker and the bike goes faster. At lower gears, your feet go faster, but you don’t have to push quite as hard to get moving!
Unlike the gears on a bike, your car, truck, van, or SUV’s transmission is extremely complex, and therefore have more complex needs. Bike chains only require a greasing once-and-again, while transmissions require regular flushes of specialized transmission fluid. Dealing with significant force and friction regularly, transmission components will wear quickly if not properly lubricated. It is important to ensure your transmission receives regular maintenance and repairs from a reputable auto shop when necessary, to ensure its continued function.