Cone wrench
Encyclopedia
Bicycle
A bicycle, also known as a bike, pushbike or cycle, is a human-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A person who rides a bicycle is called a cyclist, or bicyclist....
maintenance to access flats on axles where very little of the axle is exposed.
It is similar to an open-ended wrench
Wrench
A wrench or spanner is a tool used to provide grip and mechanical advantage in applying torque to turn objects—usually rotary fasteners, such as nuts and bolts—or keep them from turning....
but much thinner: typically about 2 mm thick, compared to approximately 7 mm for a standard open-ended wrench.