Bikes are prohibited on all trails, and are forbidden from traveling cross-country within the national park boundaries. The park's established scenic drive is open to road or mountain bikers, although you need to be aware that the 18-mile road through the park is narrow and winding, and can be crowded with motor vehicles during the summer.
Because mountain bikers are not welcome on national park hiking trails, you'll have to leave Bryce in search of trails. Fortunately, you won't have to go far -- the Dixie National Forest, which abuts the park, has numerous mountain biking opportunities.
Mountain bikes can be rented across the road from Ruby's Inn at the American Car Care Center (tel. 866/866-6616 or 435/834-5232; www.rubysinn.com) for $20 for up to six hours and $35 for a full day.