Just outside Tandragee. Short but fun. There is a variety of jumps, from one-foot jumps to eight-foot jumps, and including the road gap! If you're in the area they are worth a blast.

Located 5 minutes from the M1 Junction 10, on a slip road from one of the main town roundabouts.
10Km of purpose-built trail around the lakes, nice twisting sections of single-track. Mostly on the flat, but well worth a visit. A good family spot.

Immediately N of Markethill, SE of Armagh on A28 Armagh/Newry Rd.
This 6.6 km family cycling trail is a circular route through Gosford Forest park. The trail combines forest roads with 2 short sections of singletrack. A great spot for the family.

7 miles SW of Newry, take sign for Forkhill from border end of Newry bypass.
Great trail off the top of the mountain, but you need to carry your bike to the summit. Great scenery and a good hilly tarmac route too.