Mormon trail on South Mountain is an all around sweet downhill trail. Note, this trail is also called the 24th Street trail and is not the Mormon Loop trail that parallels National. Many riders prefer to ride up Mormon Loop and then down National.
The Mormon, aka 24th Street, downhill drops to the valley floor from the Mormon loop junction with the connector to National. This trail is not at all like the Loop trail. This downhill terrain is comparable to Geronimo and Holbert. Downhill bikes recommended but not required. In fact, I think Mormon even has tougher lines than Geronimo. The good thing about Mormon is that it has it’s own trailhead on 24th Street, and is mostly rideable on the uphill (thanks to a few flat spots to catch your breath as you ascend).
Why would you ever ascend Mormon? One of my favorite rides is Javelina-Mormon Loop-National-Geronimo. A short mile road ride to the Mormon TH and you can ascend the 700 plus feet in just over a mile. Back on the mountain you can drop down Mormon Loop or National, continue up National and ride Geronimo again, connect to Holbert or Corona Loma and Desert Classic… the mountain is yours. Riding up Mormon is the carbon friendly self-shuttle to anywhere in the park.