According to some embodiments, an adjustable assembly for a bicycle includes a lower tubular support configured to be attached to a bicycle frame; an upper tubular support configured to be attached to a bicycle saddle; an expansion portion support member positioned within an interior space of the lower tubular support; an expansion portion disposed at an upper end of the expansion portion support member; and a resilient member configured to provide an upwardly-directed force to the upper tubular support to provide movement of the upper tubular support away from the lower tubular support.