Are bicyclists supposed to ride as far to the right of the roadway as possible?
No! Many state vehicle codes say that bicyclists should operate as far to the right as is practicable, and note that in many situations it is safer and more appropriate for bicyclists to operate away from the right hand edge of the roadway. For example, the right edge of the roadway can collect debris, broken glass, sand and gravel, and other potential hazards for a bicyclist, while drainage grates, crumbling roadway edges, utility covers, and other surface irregularities can create a dangerous situation for bike riders. So it is perfectly legal and acceptable for bicyclists to be riding in the middle of the right hand travel lane.
In addition, on streets with narrow travel lanes (for example 10 or 11 feet), bicyclists may feel more comfortable riding in the middle of the lane ("taking the lane") because there really isn't enough room for a motorist to safely pass them while staying in the same lane.
You can review your state vehicle code as it relates to bicycling by visiting the League of American Bicyclists. In addition, if you have any questions or concerns about the legal status of bicyclists in your community, you should contact the Thunderhead Alliance to see if there is a state or local advocacy group who may be able to help.