The park scenery — be it desert sands, forests, or challenging mountains — can be enjoyed better from a bicycle saddle than from a car seat. And I've found that the National Park Service has afforded bicycle riders some advantages not enjoyed by those in cars.
Probably the biggest bonus for bicycle travelers is the existence of bike-in/hike-in campgrounds in some parks.
I discovered one of these years ago after a long slog into the Grand Canyon National Park. The Mather Campground offers shared campsites for hikers and bicycle riders; no reservations; no long lines; and just $6 a night.
If you can, it would be a good idea to check your park destination for such bicycle camping facilities. Yellowstone, for instance, notes logistical problems for bicycle travelers in the park, even though hike/bike campsites are available.
Although bicycles are not allowed on the many hiking trails that criss-cross the national parks, they usually are allowed on all paved roads, including those that prohibit private vehicles.
On my visit to the Grand Canyon, the car-bound crowds all jammed into the parking lots. I rode my bike along a rim road assigned to shuttle buses (now the Hermit Road Greenway) and enjoyed many amazing views, without heavy traffic or crowds. I've had similar experiences on the valley floor at Yosemite National Park and the Cades Cove loop at Great Smoky Mountains National Park.
For bicycle tourists, feeding the bears is not the big danger, it's car and RV traffic. The national park roads are often narrow and shoulderless. The twisting routes that make many parks so scenic also can lead to danger for bicyclists during the crowded summer season.
But a lot of the motor vehicle traffic is a Memorial Day to Labor Day phenomenon. If you go before or after those dates the traffic drops off precipitously.
Gorp Top 10
The Gorp.com travel site list the top 10 national parks for bicycling. I haven't been to many of these, but I'm sure they've done their homework.
The only suggestion I'd recommend is adding the Natchez Trace Parkway to the list. It's a 444-mile historic route through Mississippi, Alabama and Tennessee that has become popular with bicyclists.
Here's the Gorp.com top 10 national parks for bicycling:
Big Bend, Texas
Rocky Mountain, Colorado
Grand Teton, Wyoming
Death Valley, California
Crater Lake, Oregon
Photos above from trips to Olympic National Park. Top: Elk crossing Hoh River; bottom: touring bicycle parked on Crescent Lake.