Hub Gear

A hub gear, internal-gear hub, or just gear hub is a gear ratio changing system commonly used on bicycles that is implemented with planetary or epicyclic gears. The gears and lubricants are sealed within the shell of the hub gear, in contrast with derailleur gears where the gears and mechanism are exposed to the elements. Changing the gear ratio was traditionally accomplished by a shift lever connected to the hub with a Bowden cable, and twist-grip style shifters have become common.

Hub gear systems generally have a long and largely maintenance-free life though some are not suitable for high-stress use in competitions or hilly, off-road conditions. Many commuter or urban cycles such as European city bikes are now commonly fitted with 7-speed gear-hubs and 8-speed systems are becoming increasingly available. Older or less costly utility bicycles often use 3-speed gear-hubs, such as in bicycle sharing systems. Many folding bicycles use 3-speed gear-hubs. Modern developments with up to 14 gear ratios are available.

Famous quotes containing the words hub and/or gear:

“We recognize caste in dogs because we rank ourselves by the familiar dog system, a ladderlike social arrangement wherein one individual outranks all others, the next outranks all but the first, and so on down the hierarchy. But the cat system is more like a wheel, with a high-ranking cat at the hub and the others arranged around the rim, all reluctantly acknowledging the superiority of the despot but not necessarily measuring themselves against one another.”
—Elizabeth Marshall Thomas. “Strong and Sensitive Cats,” Atlantic Monthly (July 1994)

“For women ... bras, panties, bathing suits, and other stereotypical gear are visual reminders of a commercial, idealized feminine image that our real and diverse female bodies can’t possibly fit. Without these visual references, each individual woman’s body demands to be accepted on its own terms. We stop being comparatives. We begin to be unique.”
—Gloria Steinem (b. 1934)