1.  Field of the Invention
This invention relates generally to a device for limiting rotation of a wheel, and more particularly, but not by way of limitation, to a device that may be placed onto the individual wheels of a skateboard to limit rotation of the wheels. 
2.  Description of the Related Art
A typical skateboard has a deck, two trucks, and four wheels.  In its simplest form, riding a skateboard involves standing on the deck and pushing off the ground to propel the skateboard along the ground on the wheels.  It is common, however, for skateboard riders to perform tricks that involve the wheels of the skateboard leaving the ground.  These tricks, and even tricks for which the wheels do not leave the ground, require balance and particular movements, both of which may be perfected through extensive practice.  The wheels of the skateboard complicate such practicing, as performing a trick incorrectly or incompletely could result in the skateboard rolling away, causing the rider to fall. 
Several training aids have been developed to address this problem.  These typically require some modification of the skateboard, such as removing the wheels or adding additional elements.  These modifications may be difficult and, more importantly, may change how the skateboard functions in some significant way: make the skateboard heavier, prevent access to elements such as the underside of the deck for balancing tricks, prevent the proper functioning of the trucks, etc.  Thus, once the modifications are removed, the skateboard no longer behaves how it did when the rider was practicing, forcing the rider to re-learn certain elements. 
Based on the foregoing, it is desirable to provide a device that limits the rotation of the wheels of the skateboard so that the skateboard cannot roll while the rider practices tricks. 
It is further desirable for the device to allow the user to learn tricks, develop muscle memory, train reflexes, and get over fear. 
It is further desirable for the device to be easy to install without tools and without removing parts or otherwise modifying the skateboard, allowing the device to be temporarily installed to the skateboard, such that it stays in place while the rider performs tricks, and easily removed so that the rider can resume normal operation of the skateboard. 
It is further desirable for the device to be lightweight so that it does not affect the weight and general feel of the skateboard and does not change the center of gravity of the skateboard. 
It is further desirable for the device to work with a variety of skateboard dimensions and configurations. 
It is further desirable for the device to allow access to the center, nose, and tail areas of the board, allowing for contact with surfaces and obstacles such as rails, stairs, and platforms.