A few facts about transportation related taxes. First, road wear from weight is a non-linear function. At first, there is a tiny amount of wear from a 3,000 lb. car or a 6,000 lb. SUV. Wear starts to increase however as the weights go up at some point, more like 20,000 lbs and then increase dramatically. To see that, imagine a million pound vehicle going down the road. It would crack the concrete. 
Wear is meaningless for most roads as majority of the road never sees traffic. Shoulders, bridges, center medians simply wear out over time. 
Taxing the sale of 10,000 bikes sold each year would generate about 1.5 million, minus $100,000 to administer the tax. That buys two intersections in the state.
Locally we spent $170 million on Wilamut bridge, $70 million on the I-5 Beltline flyover, and the Beltline work will run $300-$500 million. And that is just our area. So 3/4 billion in local projects and they want to raise $8.2. billion. It is still not enough. 
Roads are expensive.