How do you describe a bicycle?

Well, how would you go about describing a bicycle? It's a mode of transportation, isn't it? It has two wheels connected by a frame, with a seat for the rider and pedals for propulsion. Some bicycles come with gears for varying the level of resistance, while others are designed for specific purposes, like mountain biking or road racing. And of course, there are all sorts of different styles and designs to choose from, from classic cruisers to sleek and modern road bikes. So, what would you say are the key features of a bicycle, and how do they make it an effective and enjoyable mode of transportation?