Gina and I traveled to Harrisburg PA for our 2008 4th of July Trip. I found a lot of info about the area trails by visiting the Susquehanna Area Mountain Bike Association (SAMBA).
Swatara State Park – Harrisburg – Multi-use
Nicely groomed trails. A good 6.5-7 mile ride. Not too challenging. It would be a fast mtb. xc course. Similar to Explore Park.
Weiser State Park – North of Harrisburg – Multi-use
Rocky single track, jeep roads, and snowmobile trails. Would be a good place to ride if you had a suggested route. Reminded me of the Dragon’s back minus the lung busting climbs.
Govenor Dick – South of Lebanon – Multi-use
We ran and biked here. These are some rocky trails. Trail 15 is one crazy ride. Lots of big rocks to maneuver over. I really like the ride on trail 15. It was pretty technical. Lots of black raspberries here for a mid ride snack!
Michaux – South of Shippensburg – Multi-use
Supposed to have some of the toughest trails in the east. Lots of rocks here. Reminded me of the Glenwood Horse Trail near Roanoke. We stopped by the Pine Grove Furnace Park office to get some maps and recommendations. We ended up riding off of Ridge Road. We also had some old race maps from http://www.racemichaux.com I would suggest getting a local to give you a suggested route. We spent a lot of time looking at our map. This place was loaded with blueberries. They were everywhere. Nice treat.
Rocky Ridge County Park – York – Multi-use
For a county park this place has it all from beginner to advanced trail. Lots of fun.