[Michele]

First thing, inflated rubber tires, for bicycles, are good for comfort. During WWII, it was not at all uncommon to see bicycles with wooden wheels. These are hard on that part of the body that supports most of the biker's weight. On the plus side, they are much tougher, and a present-day highway that has seen only average damage due to lack of maintenance would be less of a problem with these sturdier (and heavier) wheels.

Mass production of bicycles requires decent metalworking industries. But in a post-apocalypse scenario you could probably have bicycles for a century, based on parts scavenged by other bikes. Blacksmith's workshops would adapt parts. You'd have a nice market for spare parts.

As to aesthetics and speed, a case can be made for 4-wheeled carts that are normally pedal-propelled - and thus even slower than a bike. However, in emergencies (read combat and evasion), they carry a pair of solid-fuel rockets. This is TL3-4 tech. The boost is measured at most in tens of seconds, otherwise they'd be too heavy for everyday travel. But they'd make for a few exciting high-speed moments.