A cycling computer, comprising interfacing means and attaching means so as to attach the interfacing means to a bicycle via the attaching means, wherein the interfacing means comprises a cycling computer user interface unit and the attaching means comprises a base for attaching the cycling computer user interface unit to the bicycle, the cycling computer further comprising: means for mounting the attaching means to the bicycle, characterized in that the cycling computer user interface unit comprises a display for displaying exercise information, and the cycling computer further comprises: means for mounting the interfacing means to the attaching means by penetrating at least part of the attaching means and at least part of the interfacing means, wherein the means for mounting the interfacing means comprises a shaft configured to attach the cycling computer user interface unit to the base, wherein the shaft penetrates at least part of a body of the base and, when attached, fastening elements (218A, 218B) of the cycling computer user interface unit; wherein the cycling computer further comprises a projection member for moving the shaft in a direction of a longitudinal degree of freedom when the projection member is pressed so as to bring out at least one neck (260A and 260B) of the shaft from the base; and wherein the cycling computer user interface unit, when mounted to the base, is configured to serve as a double swing switch such that the cycling computer user interface unit has a limited rotational degree of freedom about the shaft, and when the cycling computer user interface unit is rotated about the shaft, a function of the cycling computer user interface unit is performed, wherein the double swing switch enables an interface through which at least two different functions can be performed, the double swing switch having a swing function in both rotational directions and at least one switch button for each rotational direction. means for mounting the attaching means to the bicycle, characterized in that the cycling computer user interface unit comprises a display for displaying exercise information, and the cycling computer further comprises: means for mounting the interfacing means to the attaching means by penetrating at least part of the attaching means and at least part of the interfacing means, wherein the means for mounting the interfacing means comprises a shaft configured to attach the cycling computer user interface unit to the base, wherein the shaft penetrates at least part of a body of the base and, when attached, fastening elements (218A, 218B) of the cycling computer user interface unit; wherein the cycling computer further comprises a projection member for moving the shaft in a direction of a longitudinal degree of freedom when the projection member is pressed so as to bring out at least one neck (260A and 260B) of the shaft from the base; and wherein the cycling computer user interface unit, when mounted to the base, is configured to serve as a double swing switch such that the cycling computer user interface unit has a limited rotational degree of freedom about the shaft, and when the cycling computer user interface unit is rotated about the shaft, a function of the cycling computer user interface unit is performed, wherein the double swing switch enables an interface through which at least two different functions can be performed, the double swing switch having a swing function in both rotational directions and at least one switch button for each rotational direction. means for mounting the interfacing means to the attaching means by penetrating at least part of the attaching means and at least part of the interfacing means, wherein the means for mounting the interfacing means comprises a shaft configured to attach the cycling computer user interface unit to the base, wherein the shaft penetrates at least part of a body of the base and, when attached, fastening elements (218A, 218B) of the cycling computer user interface unit; wherein the cycling computer further comprises a projection member for moving the shaft in a direction of a longitudinal degree of freedom when the projection member is pressed so as to bring out at least one neck (260A and 260B) of the shaft from the base; and wherein the cycling computer user interface unit, when mounted to the base, is configured to serve as a double swing switch such that the cycling computer user interface unit has a limited rotational degree of freedom about the shaft, and when the cycling computer user interface unit is rotated about the shaft, a function of the cycling computer user interface unit is performed, wherein the double swing switch enables an interface through which at least two different functions can be performed, the double swing switch having a swing function in both rotational directions and at least one switch button for each rotational direction.