This is a motorcycle park, but it is extremely fun for mountain bikers and BMX riders as well. The best trails are carved into and around a deep gully. There are some very nice drop-ins where your bike actually becomes airborne with little or no effort. Most people I've taken there were unnerved by the steep drop-ins at first, but after a while, they couldn't get enough. I used to live in Manhattan and would spend a whole Saturday here. I can't recommend it enough and it's a good change of pace from the usual single track loops in the area.
How to get there:
From Manhattan, take Tuttle Creek Blvd (east side of town, Also labeled as US Hwy 24 West) North to Kansas Hwy 13 North and turn right on 13. This highway will take you across the Tuttle Creek Reservoir dam and spillway (way from which lake water spills). Just on the East side of the spillway, you will see on your right a paved road called Dyer Rd. Turn right on Dyer Road so that you are now heading south. After a little less than half a mile, you will see a sign on your right labeled Spillway Cycle Area. Turn right here and park in the designated lot knowing you have found it!
Motorcycle and ATV traffic can become dangerously high for slower-moving mountain bikes on sunny weekends.