Abstract: A fitting structure of a bottom bracket shell of a bicycle contains: a hollow body having a receiving orifice. A first engagement element includes a first engaging section, a first aperture, and a first tilted guide portion. A second engagement element includes a second engaging section, a second aperture, and a second tilted guide portion. A first sleeve includes a first accommodation portion, a first connection portion, a first rib, a first abutting portion, and a first coupling section, wherein a first conically inclined face is defined between the first sleeve and the first tilted guide portion. A second sleeve includes a second accommodation portion, a second connection portion, a second rib, a second abutting portion, and a second coupling, wherein a second conically inclined face is defined between the second sleeve and the second tilted guide portion.

Abstract: A children's tricycle comprises a body, a front wheel pivotally assembled to the body, a first pedaling assembly assembled to the front wheel, a second pedaling assembly assembled to the front wheel, a screw for making the first pedaling assembly threaded with the second pedaling assembly. A first inserting rod of the first pedaling assembly and a second inserting rod of the second pedaling assembly are connected to the front wheel separately, such that the first and second pedaling assemblies can be assembled to or detached from the front wheel quickly. The first and second pedaling assemblies can be assembled to the tricycle for the child to step on, and can also be detached from the tricycle when the child is learning to walk, such a tricycle is not only money-saving since the parents don't need to buy a special baby walker additionally, but also has high convenience and security.

Abstract: The wobble bearing axle assembly is used for engaging the upper body of a person for use in human powered vehicles and exercise equipment. The wobble bearing assembly converts linear input force derived by the operator into rotational force, which is directed toward the forward propulsion of a wheel. The wobble bearing axle assembly comprises a wobble bearing, a wobble axle, at least two engagement members a first arm and a second arm. The wobble bearing is disposed upon the oblique retainer of the wobble axle. The oblique retainer of the wobble axle is angled offset from the axis of the wobble axle Y. The engaging members are rotatably affixed with the first and second arms through pins which is longitudinally disposed through complementary orifices through the first and second arms and the engaging members respectively. In some preferred embodiments additional bearings are engaged with the pedals powered by the legs of the operator.

Abstract: Disclosed are systems and methods for converting linear motion into circular motion.