TuningHost on Instagram: "To give a better idea, we can imagine what happens when we block a bicycle pump's hole with our finger. If we block the hole and simultaneously pull the pump's plunger upwards, we feel a certain resistance due to the air under the plunger, which expands and drops in pressure. Releasing the plunger, we notice that the air behaves like elastic and pulls the plunger back in the opposite direction. This effect allows the reed valves to reduce the pumping losses, gaining abo