A C-spanner is a spanner with a C-shaped head. It is applied in loosening or fastening lockrings of components such as some bicycle headsets and bottom brackets.
The C-Spanner engages the holes of a round locking and assists the mechanic in tightening it without damaging vital components when rotating. It is frequently used in conjunction with older threaded headsets or some bottom brackets. For long-distance cyclists, particularly those who work on their bikes, a C-spanner is an incredibly useful item for securing bearings or realigning threaded components. Although not as frequent in newer bikes, the tool is useful in full bicycle tool sets.
