At the Canyon Village in Yellowstone National Park it is not wise to bring a mountain bike. There is not many places you can ride a bike in the park. Oh yeah, there is Dunraven Pass. And the dirt road ride up Mount Washburn. But other than that there’s not really a place to go riding.
No time to fret. Just throw on some hiking shoes and head out on one of the many trails. Cascade Creek is fun.