A bicycle operating device comprises a mounting clamp and a restricting structure. The mounting clamp is configured to be mounted to a bicycle tube member. The mounting clamp comprises a first radius portion, a second radius portion, and a clamp opening. The first radius portion defines a first inner radius. The second radius portion defines a second inner radius different from the first inner radius. The bicycle tube member is to extend through the clamp opening. The clamp opening is defined by the first radius portion and the second radius portion. The restricting structure is provided on the second radius portion and is configured to restrict relative movement between the second radius portion and an adapter member at least in a circumferential direction of the second radius portion.