Bicycles are simply a method of generating rotational mechanical movement from biological sources.
That rotational energy can be used for anything where a motor would be used.
The items below have all been successful in that they accomplish the original design goal/intent, but we don't really see them in modern life because small electric and liquid-fuel motors do the same job faster and with less sweat.
with sufficient plumbing, a water source, and a purpose a bicycle can lift water.
This one is essentially a "rubbee" style of interface so a normal bike can power the tool by tyre friction. This bike could be taken off and used for other purposes. This will cause wear on the tyre just like a set of rollers, so tyres will wear faster.
By comparison, a dedicated setup might have replaced the rear wheel, locating the pump's axle where the wheel's axle was, and fitting a suitably-sized cog so the chain could drive it. If the derailleur was left in place then several cogs could produce different flow rates for the same RPM, but the bike can't be used for anything else.
Bomb shelters need ventilation, which often needs to be forced so to not asphyxiate the occupants. Air raids of WW2 were very likely to stop any electricity flow, so a human powered air pump was the answer.
In the same environment, a pedal-powered generator could run a radio set for information, and for lighting. They also provide warmth, for the riders.
A bike-style setup could be installed as a backup to main pumps, enough to keep the mine running while repairs are effected.
It has pedals, crank, and a seat. The same general setup could run a die filer, a scroll saw, a small bandsaw or circular saw. A large flywheel would help keep the machine driving forward if it hits something tough.
Most spinning wheels were treadle-powered, but by the same token they could be pedal-powered.
Hydraulics are awesome and terrifying at the same time. With long duration
low power input, a hydraulic ram can build some insane pressures resulting in massive force multiplication. Here its being used to split logs for firewood.
Concepts like the Dynapod and Energy Cycle were intended to be a human-powered stationary engine, that could run a range of devices in the field.
The Dynapod could drive pumps, corn grinders, winnowing machines, forge blowers, grinding machines, drilling machines, potter's wheels, paint sprayers, crop dusting equipment, cassave graters, coffee pulpers, grain hullers, fibre decorticators, threshers, balers, band saws, tire pumps and sewing machines. It could also be used to generate electricity.
These could run in direct drive 1:1, or 3:1 or 10:1 so the speed and torque requirements of the driven gear were met.
These could even be used to till/plough a field by dragging a weighted implement across the ground on a wire rope.
More info at https://www.lowtechmagazine.com/2011/05/pedal-powered-farms-and-factories.html