Abstract: The method for manufacturing a metal material with an intermediate hollow and two solid end portions includes a step for preparing a first mold for manufacturing a roughly-shaped metal material with a first inner solid end hollow and a lengthwise intermediate hollow of a preset length. A conical portion is formed around am outer end hole of the mold. The outer conical end of the metal material is pressed in the intermediate hollow to form a second outer end portion of the metal material. Thus, a finished product of metal material with two solid end portions and an intermediate hollow is manufactured. Such a method can surely simplify the processes of manufacture, lowing the cost of production, and strengthening the integrated structure of products.

Abstract: A disc brake oil-adjusting device for bikes includes a handle, a main cylinder and an auxiliary cylinder having one end communication with the main cylinder and the other end protruding out of the handle. An adjusting device screws with the interior of the auxiliary cylinder and has an adjusting rod and turning button combined with a tail end of the adjusting rod. A protective cover and a grip are pivotally connected with the handle, and the protective cover has an opening for receiving the turning button so as to be located near the grip and turned to move the adjusting rod move so as to control the auxiliary cylinder in its capacity to absorb excessive brake oil, lowering the temperature of the disc to keep safety in running a bike.

Abstract: An oil-storing device for a bike saucer-brake includes two oil-storing chambers formed in an interior of a grip, a plate separating the two oil-storing chambers. The plate has a hole communicating two oil-storing chambers for brake oil to flow through. Further, an oil delivery pipe is provided inserting into an outlet tubular portion of the grip, extending inward to reach on the plate, communicating with either of the two oil storing chambers through a sucking hole. Thus, the two oil-storing chambers can store more oil, sucking in oil back to prevent snap locking of the brake from happening. Therefore the device insures safety of a rider in riding even if a bike inclines.

Abstract: A crank assembly for a bicycle includes a drive plate and an elongated crank arm which are separately formed. The bicycle includes a sprocket with a fixed rotating shaft of a rectangular cross-section. The drive plate has an internal peripheral wall that defines a shaft hole, an inward flange that projects from the inner peripheral wall into the shaft hole in such a manner that the shaft extends through the shaft hole, and several angularly equidistant through-holes around the shaft hole. The crank arm has an end portion with a fastener hole, an annular flange portion which projects horizontally from the end portion and which has a vertical abutting face that abuts on the inward flange of the drive plate, and a rectangular receiving space formed through the flange portion to form a portion of the fastener hole and to receive the shaft. The fastener hole has an outer section with a shape different from that of the rectangular receiving space.

Abstract: A bicycle sprocket assembly includes a small sprocket wheel, and a large sprocket wheel coaxial with the small sprocket wheel and provided with several guide units each of which includes a notch formed in the large sprocket wheel, and a chain guiding piece that is secured to the inner side surface of the large sprocket wheel and that is adjacent to the notch. The notches are respectively formed in some spaced-apart sprocket teeth of the large sprocket wheel. Each of the notches is formed by an outer guiding surface which extends from a tooth tip to the corresponding tooth valley and which makes a junction with the inner guiding surface of the corresponding piece, so as to slide the chain between the inner and outer guiding surfaces. The pieces are inclined with respect to axial and radial directions of the sprocket assembly.