actually, it's pretty common knowledge among most serious cyclists that we already pay taxes for roadways. If you lump together all the gasoline taxes, license fees, etc that are devoted to highways, it comes to about 60% or so of all actual costs to build and maintain the roadways. (Not quite sure of the exact percentage, but it's somewhere near that. Anyway, you catch my drift.) It should also be pointed out that the lion's share of this funding is directed toward interstates and other primary roadways where bicycles are generally excluded. So where does the balance come from? General fund revenues paid by all taxpayers - cyclists, transit users, property owners, the whole gamut. Studies have been made that show cyclists actually pay more than their share, and in fact subsidize motorists to an extent. General fund revenues are used more often for the local streets, which happen to be where most cyclists do the vast majority of their riding.
This is something I wish would get more attention so that motorists would realize we pay our share too, and are not freeloaders on the roadways. We are riding on PUBLIC rights-of-way, which means meeting the travel needs of ALL the public, not just those that choose to go by motor vehicle.