Abstract: A magnetism generation device is attachable to a disc brake rotor adapter for a bicycle hub. The magnetism generation device comprises a magnetism generation portion and a holder. The holder has a first portion and a second portion. The first portion supports the magnetism generation portion. The second portion is releasably attached to the first portion with a portion of the disc brake rotor adapter disposed between the first and second portions while the magnetism generation device in an installed state on the disc brake rotor adapter.

Abstract: A bicycle magnetism generation device and a disc brake adapter are configured to allow a rotation state of a bicycle wheel to be detected in a suitable manner. The bicycle magnetism generation device includes a magnetism generator generating magnetism. In a state where the disc brake rotor is coupled to a hub of a bicycle, the bicycle magnetism generation device is at least partially arrangeable between the disc brake rotor and the hub.

Abstract: A magnetism generation device is attachable to a disc brake rotor adapter for a bicycle hub. The magnetism generation device comprises a magnetism generation portion and a holder. The holder has a first portion and a second portion. The first portion supports the magnetism generation portion. The second portion is releasably attached to the first portion with a portion of the disc brake rotor adapter disposed between the first and second portions while the magnetism generation device in an installed state on the disc brake rotor adapter.

Abstract: A disc brake rotor adapter is configured to detect a rotational state of a bicycle wheel. The disc brake rotor includes an adapter and a magnetism generation device. The disc brake rotor adapter is configured to attach a disc brake rotor main body to a hub of a bicycle. The adapter includes an adapter main body, a magnetism generation portion and an attaching portion. The adapter main body includes an inner portion and an outer portion. The inner portion includes a second spline configured to be engaged with a first spline provided on the hub. The disc brake rotor main body is coupled to the outer portion. The attaching portion attaches the magnetism generation portion to the adapter main body in a manner irrelevant to a fixing function of a fixing member. The fixing member is configured to fix the adapter to the hub.

Abstract: A bicycle magnetism generation device and a disc brake adapter are configured to allow a rotation state of a bicycle wheel to be detected in a suitable manner. The bicycle magnetism generation device includes a magnetism generator generating magnetism. In a state where the disc brake rotor is coupled to a hub of a bicycle, the bicycle magnetism generation device is at least partially arrangeable between the disc brake rotor and the hub.

Abstract: A disc brake rotor adapter is configured to detect a rotational state of a bicycle wheel. The disc brake rotor includes an adapter and a magnetism generation device. The disc brake rotor adapter is configured to attach a disc brake rotor main body to a hub of a bicycle. The adapter includes an adapter main body, a magnetism generation portion and an attaching portion. The adapter main body includes an inner portion and an outer portion. The inner portion includes a second spline configured to be engaged with a first spline provided on the hub. The disc brake rotor main body is coupled to the outer portion. The attaching portion attaches the magnetism generation portion to the adapter main body in a manner irrelevant to a fixing function of a fixing member. The fixing member is configured to fix the adapter to the hub.

Abstract: A hub assembly attachment unit includes an attachment and a magnetism generator. The attachment is attachable to a thread at an end of a portion of a bicycle hub assembly that is rotatable relative to a hub axle in a direction extending along a rotational axis of the bicycle hub assembly. The thread is arranged coaxially with the rotational axis of the bicycle hub assembly. The magnetism generator is arranged integrally with the attachment.

Abstract: A bicycle component is basically provided with a controller, a first connection part and a second connection part. The first connection part is connected to a first transmission path configured to transmit electromagnetic waves. The second connection part is connected to a second transmission path configured to transmit electricity. The controller is configured to establish a communication path with other bicycle components through the first transmission path by communicating with the other bicycle components via the second transmission path.

Abstract: A bicycle component is basically provided with a controller, a first connection part and a second connection part. The first connection part is connected to a first transmission path configured to transmit electromagnetic waves. The second connection part is connected to a second transmission path configured to transmit electricity. The controller is configured to establish a communication path with other bicycle components through the first transmission path by communicating with the other bicycle components via the second transmission path.