Core Creek, Located in Langhorne, Pa, is a great training ground for beginner riders. There is little climbing.
Core Creek was my first experience into MTB in Pennsylvania. Located off of Bridgetown Road, Core Creek is a mostly forest singletrack park with many technical areas, stream crossings and log crossings. (Side note: our last excursion there revealed that a number of log crossings had been cleared away by the park service. I think they were missing the point of the crossings.)
The way to access the park is at the North Corner of the Duchess Parking area. A large portion of the park behind St. Mary Medical Center in the open field side of the lake (Luxembourg) has picnic, ball field, walking and playground areas. But the Side of the lake that is forested (South) is were the trails are. Most of the trails off of the Duchess area are singletrack, well groomed and very pleasant to cycle. There are small terrain changes and easy obstacles. Following the trails to the Soccer Field Access area reveals an entrance that dives South, back into the forest. One can option to keep to the sides of the cornfields and do multiple loops, or one can dive into the south forest area and avail themselves of the several loops of track. There are log crossings and a stream crossing or two. The loop will deposit you back to the Soccer Field Access.
If you jog right and left, without exiting onto the soccer field, you will find a trail that zigzags across a stream bed several times, cross two small bridges and bring you up a hill to a singletrack heading east. This skirts along the side of the lake. Eventually you will wind up in the East trail area. In 2004, we could count multiple log crossings with very enjoyable ramps and challenging stream crossings, but the park rangers clearly do not get the MTB mindset, here. They removed a large portion of them. No worry, a free day here and there and I hope to provide some nice side trails with a log or two plus ramps for us enthusiasts. After all, trees fall in the forest, get used to it. Learn to hop logs. It's what they are there for!
You will find that the trail system winds past Woodbourne Road. You can cross this road at your own peril. There is a whole additional set of trails behind Maple Point School that offers challenging terrain, log piles with ramp ups and downs, small bridges and plenty of elevation changes. By using all of these systems, it is possible to spend 2 solid hours MTB'ing using new trail without lapping.