It was mentioned earlier, and bears repeating:
The Highway Trust Fund money goes to all kind of projects besides fixing highways. Studies on rail projects, building bike paths, funding battery research, etc. Much of it also goes into the pockets of politicians controlling these projects.
When I fill my tank, I pay a tax which is supposed to build and fix roads.
I don't like paying that tax so some bikers in Colorado can enjoy the scenery. Let them build their own bike trails with taxes on their bikes.