It is a short but not that well maintained single track there are many different trails that you can ride on in the peninsula and if you keep following one or keep following the signs you will find hard and easy trails that are clearly marked. There are a lot of trails that start out as double track but end up in a challenging single track.
Coming from the east of Frisco get off at the first Frisco exit and start heading down highway 9 towards Breckenridge then pull of to the left where it says Frisco peninsula recreation center. There are places to park near the fields. Then start heading up the paved bike path you will see a small 4*4 trail heading up a steep hill there you will find the beginning of the single track
http://www.singletracks.com/item.php?c=1&i=4613