“A moderately difficult climb to N. Platte River Rd.”
— BlakeV Vanier
This is a great section of trail minus the 6 mile ride up the canyon road. It can be done as an out and back if you're looking for some mileage. If you're getting tired, just don't do the last descent or you're fully commited to the whole thing.
The climbs are long, but they aren't overly technical. There is only one really technical part.
Start up Waterton Canyon on the nice big easy dirt road. Fortunately, you can keep your speed up and eat through the mileage. Head up past the dam and up a couple more hills until you see some singletrack as the road turns to the right.
This climb isn't too bad, with very little technical difficulty. Once you break free of the climb, keep right on the Colorado Trail and start a really fun descent.
Next you'll have a pretty long ascent at the top of which you should decide if you want to go for the whole thing or not as it's a good climb back out if you you're doing the out and back. An interesting thing about this descent is that it takes you through 3 different habitats which are easy to tell by the changing plant/tree life.
There is a bathroom at the South Platte trailhead.