BELLINGHAM, Wash. — Rose Wakeland, 13, who got her first two-wheeler at age 2, flew over a jump on a dirt trail here one recent morning like an old hand. “Good one, Rose!” a friend shouted.

Taking to the rocky, root-tangled trails of northwest Washington on a mountain bike is a rite of summer in this outdoor-obsessed corner of the nation, where the North Cascade foothills kiss the edge of town.

But now in areas like this across the West where communities and wild places meet — from Colorado’s Front Range to the necklace of towns around Lake Tahoe — a debate is raging over what the future should look like out on the trails, and whether hiking boots and knobby tires can coexist.

A bill in Congress would open up biking in federally designated wilderness, where “mechanical transport” has been banned since President Lyndon B. Johnson signed the Wilderness Act in 1964. Conservation groups have mostly lined up in opposition to the change, fearing an erosion of land protections, and some cycling groups are opposing the bill for similar reasons. But many other riders, including Rose’s mother, Char Waller, argue that wilderness rules must adapt to a generational shift in how young people like her daughter recreate. Wild places get saved and protected, she said, only when people love them and use them.