Oh boy! Something tangential to my special interest! In the late 1800s and first half of the 1900s bicycle mounted infantry units were a thing. Generally not fighting from atop the bikes, but rather maneuvering whole companies to position, and carrying supplies. Largely with advent of mass motorization they fell by the wayside but they held on for quite a while. The Dutch and Belgians had significant infantry formations on bicycles. The Japanese used them extensively in the invasion of Malaya and Singapore. And they were the back bone of NVA logistics during large parts of the Indochina Wars. The US had a few experimental units but they never saw service in a war. A bunch of armies used them for message runners.

For a force that couldn’t afford to support a large fleet of trucks, that were operating in conditions that trucks could not handle, or that were attempting to minimize their foot print to avoid air strikes, bikes served a huge role. They sit as a middle ground between trucks and simply having everyone walk. Not needing fuel, being able to handle rough terrain, faster movement than walking, and carrying significantly more than a single person can with a backpack.

Motorcycles also do a fair amount of use for similar reasons. The Soviet’s in WW2 also had large recon and exploitation forces on motorcycles, and there are lots of examples of paratrooper units using them as carriers for anti tank weapons and mortars.

We’re starting to see E-bikes show up in some modern conflicts now as well.