One of the rarest pursuits is the land speed record on a bike. There are various types mostly breaking down to paced, unpaced, and downhill(!). Since work needed to travel fast goes into dealing with air resistance, paced bikes that travel behind a moving wind break are the fastest. They don't have to be aerodynamic but a variety of engineering issues need to be met.
Donhou has made such a beast. Bizarre looking with that huge 104 tooth chain ring, but still a bicycle. Unpaced bikes have to be streamliners. I think the fastest official speed was recorded by Sam Whittingham at just under 83 mph in 2009. Serious aerodynamics and a serious athlete.