A rotation calculating system, comprising: a first optical characteristic acquiring device, configured to acquire optical characteristics for at least one feature of a first target device; and a calculating unit, configured to calculate rotation for a first rotating device based on the optical characteristics of the feature of the first target device. The first rotating device is a wheel, and the first target device is the wheel.

The selection system (1) of the transmission gears in bicycles or the like comprises a cogset (2) associated axially sliding with a hub (3) of a wheel (R) of a bicycle (B) and provided with a plurality of cogs (4) of different sizes and arranged alongside one another, starting from the smallest-sized cog (4a) to the largest-sized cog (4b), and movement means (5) of the cogset (2) on the hub (3) between a first extreme position, in which the smallest-sized cog (4a) is positioned on a transmission chain (C) of the bicycle (B), and a second extreme position, in which the largest-sized cog (4b) is positioned on the chain (C), the cogset (2) being associated with the hub (3) with the smallest-sized cog (4a) facing the wheel (R) and with the largest-sized cog (4b) facing outwards, wherein the selection system (1) comprises quick assembly/removal means (19) of the wheel (R) independently of the cogset (2).

A knee walker with four-wheel steering. The knee walker includes a frame, at least one front axle assembly, at least one rear axle assembly, a kneeling pad assembly, and a steering system. The steering system is configured to turn the rear axle assembly in the opposite direction from the front axle assembly. The opposing angles of the front and rear wheels enable the knee walker to perform tighter turns by eliminating rear wheel drag.

A knee walker with four-wheel steering. The knee walker includes a frame, at least one front axle assembly, at least one rear axle assembly, a kneeling pad assembly, and a steering system. The steering system is configured to turn the rear axle assembly in the opposite direction from the front axle assembly. The opposing angles of the front and rear wheels enable the knee walker to perform tighter turns by eliminating rear wheel drag.

A bicycle wheel securing device comprises a shaft, an axial abutment structure, a bicycle-body engaging structure, a manual actuator, and a shaft-end retaining structure. The shaft has a first shaft end, a second shaft end, and a longitudinal center axis. The manual actuator is operatively connected to the axial abutment structure to bias the axial abutment structure against a first wheel attachment part of a bicycle body in response to operation of the manual actuator in a securing state where the bicycle-body engaging structure is engaged with a second wheel attachment part of the bicycle body. The shaft-end retaining structure is at least partly disposed at the second shaft end to retain the second shaft end in the first wheel attachment part in a maintenance state where the second shaft end is positioned in the first wheel attachment part of the bicycle body.

An adjustable axle retaining structure is disclosed. The structure includes an axle receiving feature on a first leg of a fork assembly and a retaining sleeve within a clamping member on a second leg of the fork assembly. An axle is inserted through the clamping member, the wheel hub and coupled with the axle receiving feature. A component of the axle is tightened thereby moving the retaining sleeve partially out of the clamping member and toward the wheel hub until the wheel hub is in contact with both the retaining sleeve and the axle receiving feature, wherein the moving of the retaining sleeve allows the axle to radially couple the wheel hub with the fork assembly without modifying a preestablished geometry of the fork assembly.

An axle assembly for a vehicle includes an axle shaft having a bolt end and a lever end. The axle assembly includes a cam assembly coupled to the lever end of the axle shaft. The cam assembly includes a cam housing, a cam follower shaft coupled to the cam housing, and the cam follower shaft is located coaxially within the axle shaft. The cam follower shaft does not extend the full length of the axle shaft. The cam shaft is coupled to the cam follower shaft, and a lever is coupled to the cam assembly. The lever is rotatable from an open position to a closed position, and an angle of maximum rotation for the lever between the open position and the closed position is less than 180 degrees.

A dropout assembly comprises a first dropout that includes a first through hole configured to receive an axle for a bicycle wheel. The dropout assembly also comprises a second dropout that includes a second through hole and a mounting surface. The second through hole is configured to receive the axle for the bicycle wheel. The dropout assembly also includes a rotational control mechanism that is configured to mount to the mounting surface of the second dropout. The rotational control mechanism includes a nut and a nut cover.

This bicycle stand installation adapter (1) is equipped with: affixed bodies (11) to be affixed to left and right chain stays (8) constituting parts of the frame (7) of a bicycle (100) with quick-release skewers; affixing pieces (12) that are affixed to the affixed bodies (11) and extend along the chain stays (8); and spacers (25) to be interposed between left and right rear end parts (10) and the corresponding affixing pieces (12), the left and right rear end parts (10) being located at the back end of the frame (7). The affixing pieces (12) are affixed to both ends (5) of a substantially C-shaped dual-leg kickstand (2) to be installed on the rear end parts (10).

A quick-release device for a bicycle includes a shaft having a locking assembly at one end and an inner sleeve in another end. The inner sleeve is kept a distance apart from an end edge of a through hole of the shaft to form an inner annular trough portion at an outer end of the through hole. A threaded cylinder is insertedly connected to the inner annular trough portion. A perforation is defined in the threaded cylinder. One axial end of the threaded cylinder has a cylindrical flange. The cylindrical flange is insertedly connected to the inner annular trough portion of the shaft. A bolt is insertedly disposed in the perforation of the threaded cylinder. The bolt passes through the perforation and is inserted into the shaft to be screwed to the inner sleeve, so that the bolt presses and locks the threaded cylinder and the shaft.