A twisting device (10) for twisting or stranding electrical or optical lines (12) to form a line bundle (13). The twisting device (10) comprises at least one first twisting head (15) and a clamping device (25). The first twisting head (15) and the clamping device (25) are spaced apart from each other. The twisting device (10) has at least one detecting device (30) for capturing information indicative of a lay length of the line bundle (13). The at least one detecting device (30) can be moved relative to the first twisting head (15) and the clamping device (25).