Abstract: According to the present invention, a bearing assembly includes a rotatable hub and a porous bearing surrounding the hub, a sprocket surrounding the bearing, and means for rotating the hub relative to the bearing. The porous bearing includes “lubricant channels” containing a lubricant and having inlet openings facing toward the sprocket and outlet openings facing toward the rotatable hub so that lubricant in the lubricant channels can exit through the outlet openings to lubricate the mating surfaces of the bearing and the rotatable hub. The porous bearing is permeable to fluids and thus capable of being penetrated by lubricants and greases and thus due to its porous character includes lubricant channels that function to conduct lubricants and greases from an outer surface of the porous bearing to an inner surface of the porous bearing through lubricant channels or pores formed in the porous bearing.