Bill Hammons: Writing and Running in Boulder, Colorado


Mountain Climbing, Hiking Levels and the Yosemite Decimal System

Climbs of Colorado's Fourteeners can be classified as "walkable" or requiring a scramble (the use of hands and knees). Many climbs require more nuanced classification, however, and that's where the Yosemite Decimal System comes in handy. You'll often come across the classes of the YDS in the trail descriptions of individual peak pages.

The Yosemite Decimal System is a system for the difficulty of walks, hikes, and climbs used for mountaineering in the US. It was initially created by the Sierra Club in the 1930s for use in the Sierra Nevada, and has been a standard ever since.

The five classes are as follows, in order of increasing difficulty:

  • Class 1: Hiking
  • Class 2: Simple scrambling, with possible occasional use of the hands
  • Class 3: Scrambling, a rope might be handy but is usually not required
  • Class 4: Simple climbing, with exposure. A rope is often used. Natural protection can be easily found. Falls may well be fatal.
  • Class 5: Technical free climbing. Climbing involves rope, belaying, and other protection hardware for safety.

    In addition, in the 1950s Class 5 was further broken down into sub-classes 5.1 (easiest) through 5.14 (most difficult) to describe rock climbing, which is generally avoided in this guide.


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