"Jacobsburg is one of the few state parks that allows mountain biking, and almost every trail is multi-use. This is good and bad. The good side is that mountain bikers have lots to shred on. The down side is that there are many other users out on the trail as well. Horses, hikers, and trail runners abound at Jacobsburg. With all the tight, twisty turns it would be easy to run someone down. Combine that with a really fast, hardpacked trail in summer and mountain bikers riding in all directions— well, you get the picture.
Ride defensively and cautiously as there have been a few accidents that could have been avoided, and all involved a mountain bike. Highlights: historic site of Jacobsburg, established 1740; historic buildings; Jacobsburg Environmental Education Center; fishing; creek crossings; fast singletrack. Tread: a mix of cinder-coated singletrack, open grassy roads, woodland singletrack, paved and gravel roads, and creek crossings. During the summer these surfaces can become hardpacked and very fast."