This area is called bluebird. Roller Coaster is the main feature of this area, but there are many trails that weave in and out of this gully. Most of the area is in Chubbuck City limits (privately owned - owner allows for mountain bikers please be respectful), but if you head far enough East you'll be on BLM land and there is a barbed wire fence (with gates) so you'll know when you are there. If you head out that way there are two tracks that you can explore all you want.
This trail is super flowy and can be as hard, or as easy as you want. It is fairly braided out. You can see where jumps are and can pick and choose what your skill level will allow you to do or not do any at all. Most people ride up to where the 4x4 road crosses the gully and ride down from there. If you drop in from the rim there are some steep grades. You can ride the 4x4 trail and follow the rim around and choose where you want to drop in, there are two single tracks that drop in on the East side and the 4x4 road the crosses near the middle.
People usually park at the end of Lois lane.
Be warned, if you ride this trail in the evening the sun will blind you! If you wear sunglasses you'll feel like strobe effect as you weave through the junipers.