internal-gear

Based on tradition, the bicycle utilized an internal-gear hub, available in both 3,5 and 7-speed options.

Derailleurs cannot be used, so an internal-gear hub is used if multiple gear ratios are required.

Though they are heavier than comparable derailleur systems, internal-gear hub systems generally last longer and require less maintenance.

With financial backing from Torbensen's mother, the company was set to manufacture Torbensen's patented internal-gear truck axle.

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.