While not necessarily a bike trail this place is a lot of fun. It's pretty much just up and down the whole time going from bluff to bluff. You can start at the Lewis and Clark Monument in Council Bluffs and go in any direction from there. Lots of different trails to choose from in the forest. If things get too hairy then there are a few places to get off onto the paved country road right next to it. Just a lot of fun and you can find lots of different ways to get onto the trail. You can ride it for months and still find new things.
How to get there:
From I-80 take I-29 North and get off on the North 25th Street exit in Council Bluffs. Go right then immediately go left at the stoplight. Go through the next set of stoplights and go through Big Lake Park. At the end of Big Lake Park go left (following the sign for the Monument). Then just follow sthe signs (it will be another left approximately .25 miles down the road). Just pull in, enjoy the view, and then enjoy the ride.
There might be the occansional hiker, especially on the weekend.