Abstract: A saddle adjusting device is slidably disposed on a seat tube and comprises a seat body. The seat body is provided on a top end thereof with a saddle and includes a through portion for insertion of the seat tube. The seat body is provided with at least one seat tube clamp for clamping the seat body on the seat tube and further provided in a middle portion of the through portion with a hollow portion laterally penetrating the seat body and plural engaging grooves. The seat tube is fixedly provided with a bolt for cooperating with the engaging assembly. The engaging assembly can move along the bolt in a direction vertical to the axial direction of the seat tube to make protruding portions of the engaging assembly engage into or disengage from the engaging grooves for adjusting the position of the seat body relative to the seat tube.

Abstract: A quick release structure for a bicycle comprises a positioning post and an engaging member. The positioning post and the engaging member are disposed on the two tubes of the bicycle, respectively. The positioning post includes a stopping block and a spring. When the positioning post is inserted into the engaging member, the stopping block can be used together with the spring to restrict the positioning post in the engaging member, so that the two tubes of the bicycle can be assembled. When the stopping block is pressed, the positioning post can disengage from the engaging member. Hence, the quick release structure for a bicycle can be quickly assembled and disassembled.

Abstract: A hub assembly for a disk brake of a bicycle includes a support shaft, a hub body pivotally mounted on the support shaft and provided with two drum disks, a mounting portion protruding from one of the drum disks, a threaded section protruding from the mounting portion, a brake disk resting on the end face of the mounting portion, and a chainwheel screwed onto the threaded section and pressing the brake disk so that the brake disk is clamped between the mounting portion and the chainwheel closely. Thus, the brake disk is mounted on and detached from the hub body by screwing and unscrewing the chainwheel, so that the hub assembly is assembled and disassembled easily and rapidly, thereby facilitating a user assembling and disassembling the hub assembly.