Abstract: An anemometer for sensing shaft speed rotation includes a series of circumferentially spaced, radially extending arms and a corresponding series of wind cups, each disposed at an outer radial end of one of the arms. Each arm terminates at its inner end in a hub sector correspondingly formed as a portion of a central hub and correspondingly includes circumferentially extending, complementary offset portions and fasteners for releasably interlocking the offset portions of overlappingly to define the common central hub. The hub-connecting portion is mounted on the anemometer shaft by connector means.