A damper for a bicycle having a primary unit and a remote unit that, in some arrangements, is substantially entirely outside of the primary unit. The apparatus comprises a sensor assembly to provide ultrasound images of at least one blood vessel in a portion of a patient’s body in two perpendicular planes. Also disclosed are compositions comprising at least about 10 weight percent of non-ionized tetramantane components and other higher diamondoid components and at least about 0.