A chronograph module (1) including a plate, a primary shaft (3), and a primary disk (4) extending on an orthogonal plane to a longitudinal axis of the shaft. The primary shaft is fitted on the plate, such that the primary disk is engaged with a geartrain of the chronograph module. A removable wheel (2) is fitted on the primary shaft (3), and includes a peripheral gear structure and first (22) and second elastic arms (23) forming a clamp (30) to grip the primary shaft. A radial support surface (25) supports the elastic arms to assemble the removable wheel on the primary shaft. The arrangement and dimensions of the removable wheel produces an overlap of the removable wheel and an overlapping part of the module, such that the assembly of the overlapping part required the absence of the removable wheel whereas the primary shaft is fitted on the chronograph module.