A nonprofit is challenging Park Service guidelines on the use of electric bikes.
Public Employees for Environmental Responsibility (PEER) says the agency needs to revisit the issue and create a more thorough policy.
A Park Service policy issued during the Trump administration said that e-bikes could go anywhere regular bikes could.
That met with widespread opposition. So, the agency turned the matter over to individual parks, which resulted in legal action.
A court ordered the agency to write a new policy, but critics say those guidelines fail to address concerns over potential fire risk, conflicts with equestrians and other issues.
"And the question is, what help headquarters can provide? What sort of experience from other places, safety tips, those kinds of things, and the answer so far is nothing," said PEER spokesman Jeff Ruch. "So, each superintendent has to figure it out on his own, and that’s the gist of our complaint," he said.
E-bikes are allowed on about 13 miles of roads and trails at the Grand Canyon.