Unofficial trail (i.e., no land manager). Tight and twisty singletrack through forest and fields. Large network that is unmarked. Can get turned around easily. Relatively young trail that will get better with age, unless it's lost to suburban development. Best ridden with a local.
(from Twin Cities) 494 west to SH 5, SH 5 west to SH 41, SH 41 south to Pioneer Trail in Chaska. At the intersection of SH 41 and Pioneer Trail you will see a large Target Store on the east side of SH 41. Take Pioneer Trail west. You will see Jonathan Elementary school on your right. Turn right just after you pass the school then hang another immediate right onto a gravel road (McKnight Park). This road will lead up to a parking lot (you can see the back of the school from here). You can get to the trail from this parking lot. The address of the school is 110300 Pioneer Trail West, Chaska MN 55318.
http://www.singletracks.com/item.php?c=1&i=1735