A hydraulic bicycle is a

chainless bicycle A chainless bicycle is a bicycle that transmits power to the driven wheel through a mechanism other than a metal chain. Examples * Directly driven "ordinary" bicycle (see penny-farthing) * Shaft-driven bicycle * Belt-driven bicycle * Hydraulic b ...

that transfers power to the pedals by means of a liquid passing through tubes from hydraulic pump to hydraulic motor and back. Advantages include: * Shifting, through valves and displacement, provides either continuously variable gearing or more steps than traditional bicycles. * Shifts smoothly under full power. * Drive transmits power while pedaling forward and backward. Thus racers can power bicycle through turns by alternating short forward and backward pedal strokes. No slack or backlash occurs, in either direction. Ability to coast is maintained. * Mechanism is clean and operates silently. * Fewer moving parts (about 10 vs over 70), all of which are continuously bathed in clean lubricating fluid. * Sealed systems require less maintenance than open chain system. * Front-wheel drive and two-wheel drive systems can be implemented. (See

Two-wheel drive Two-wheel-drive (2WD) denotes vehicles with a drivetrain that allows two wheels to be driven, and receive power and torque from the engine, simultaneously. Four-wheeled vehicles For four-wheeled vehicles (and by extension, vehicles with six, e ...

) * Drive can double as a hydraulic brake, eliminating the weight, cost, and maintenance of regular brakes. * The hydraulic (hydrostatic) transmission could be useful for recumbent bicycles because the hoses may be easier to route than a long chain. * Energy recuperation, storage and power assist could be added. Disadvantages include: * Implementations to date are heavier than those of

bicycle chain A bicycle chain is a roller chain that transfers power from the pedals to the drive-wheel of a bicycle, thus propelling it. Most bicycle chains are made from plain carbon or alloy steel, but some are nickel-plated to prevent rust, or simpl ...

and

sprocket A sprocket, sprocket-wheel or chainwheel is a profiled wheel with teeth that mesh with a roller chain, chain, Caterpillar track, track or other perforated or indented material. The name 'sprocket' applies generally to any wheel upon which radial ...

designs. * Though some of the components in a sealed hydraulic system maintain constant efficiency upwards of 95% in all conditions (see Hydristor), the overall losses usually result in an efficiency of about 75% (power loss of about 25%, see

Hydraulic machinery Hydraulic machines use liquid fluid power to perform work. Heavy construction vehicles are a common example. In this type of machine, hydraulic fluid is pumped to various hydraulic motors and hydraulic cylinders throughout the machine and ...

). In contrast, a chain-and-sprocket system loses efficiency in bad weather and dirt – from 97% for clean new components down to less than 80% when worn and dirty. * The system may leak fluid causing a mess and eventual failure.

References

External links

Cannondale Jacknife (Hydraulic Concept Bike)

Engineering Students Compete To Redesign The Bicycle: hydraulic and pneumatic designs

The Purdue Tracer: An Energy-Efficient Human-Powered Hydraulic Bicycle
Cycle types {{cycling-stub