The introduction of the park shuttle has improved bicycling conditions in Zion National Park, for during the busy months, April through October, cyclists no longer share Zion Canyon Scenic Drive with thousands of cars—though two-wheelers do need to be cautious of the large buses plying the park road throughout the day. Within the park proper, bicycles are only allowed on established park roads and on the 3½-mi Pa'rus Trail, which winds along the Virgin River in Zion Canyon. You cannot ride your bicycle through the Zion-Mount Carmel tunnels; the only way to get your bike past this stretch of the highway is to transport it by motor vehicle.