Trail #100 is a classic Phoenix ride. It covers almost 11 miles from East to West and is chuck full of additional trails to suit your riding ability. I used to live very close to the Tatum Trailhead and enjoyed riding trail 100 often.
Many reviews of trail 100 say that it’s pretty easy and relatively flat. True, for some sections. But while trail 100 is the most famous trail in the area, it’s hardly the most or least difficult.
Get to know the area and study the maps…then go explore. If you want to start from the East side, be warned that the Tatum trailhead has only a few parking spots – literally – and there is nowhere else to park nearby. If they are full, you have to drive to the 40th street lot.
From the West side you can start at the Mountain View Park trailhead on 7th Avenue or the 7th Street trailhead. As most reviews tell you, the best riding is east of the Dreamy Draw. West of the Dreamy Draw has some nice singletrack, but there is quite a bit of wide flat double track too.
The Dale Wiggins Topo of the Phoenix Mountain Preserves is the best topo of the entire trail system: Includes trails 1A, 220, 3, 3A, 3B, 300, 302, 304, 200, 200A, 100A, 306, 60, 44 and even more unnamed trails.
Excellent review of a more advanced route of 100 by Continental on MTBR.com