Abstract: A device for the attachment of a derailleur to a bicycle, in particular for the attachment of a front derailleur to a support welded on a seat tube of a bicycle adjusts the position of the derailleur along at least one axis substantially perpendicular to a longitudinal axis of the seat tube of a bicycle. In particular, the device adjusts the position of the derailleur along an axis Y lying on a plane substantially parallel to a lying plane of a toothed crown associated with the bottom bracket of a bicycle and, preferably, also along an axis Z substantially perpendicular to said lying plane of a toothed crown associated with the bottom bracket. This ensures a better positioning of the derailleur with respect to the toothed crowns of the bicycle and, therefore, a better operation of the derailleur during gearshifting.

Abstract: A housing (2) for an electronic control unit for use aboard a bicycle and a battery container (3) for powering electrical devices fitted aboard, are provided with quick coupling means (6, 10), that, when coupled, also provide the electrical connection between the batteries and the control unit.