The Yosemite Decimal System is a system for rating a rock climbs difficulty. It is used in climbing areas in North America and in some areas internationally. It is comprised of 5 classes of difficulty ranging from a flat trail, to the steepest of rock faces. Classes 1-4 are assigned for routes that generally do not need the aid of a rope for protection, while class 5 routes generally require more advanced technique and equipment. Class 5 is divided into a decimal system to be more precise ranging from 5.1-5.15 Class I Flat ground, easy walking on trail
Class II Steep trail that requires occasional use of the hands or cross country travel
Class III Steep slopes that requires scrambling with the use of hands with potential to take a short fall of 5 to 15 feet
Class IV Blocky, low angle rock climbing with the potential to take very long falls.
The question of “to use the rope or not” is usually asked and proper route finding is essential to stay on the path of least resistance. 4th class terrain is usually found in the high mountains and when approaching 5th class rock climbs
Class V 5th class climbing requires the use of rock climbing specific techniques and is further clarified by the Yosemite Decimal system below.
5.1 to 5.5 Entry level rock climbs that are not vertical and generally have large hand and foot holds
5.6 to 5.8 Entry level to moderate in difficulty. More advanced movement techniques are needed but generally most people can succeed on the climb with practice. (Low angle to vertical terrain)
5.9 to 5.10 Still considered moderate in difficulty by advanced climbers but requires precise techniques, physical training and considerable experience to succeed. (Generally vertical terrain to overhanging)
5.11 to 5.12 Advanced climbs that require dedication and many years of experience. Climbers are can only climb at this level with climbing specific training and optimal health. (Vertical terrain to overhanging)
5.13 to 5.15 The extreme end of the sport. A very small percentage of the climbing population can perform at this level.(Vertical terrain to overhanging) Note: 5.10 to 5.15 ratings are sub classified into a,b,c, and d ratings. Example: 5.10d (pronounced "five ten d"). Each letter grade represents a very noticeable increase in difficulty from the previous. A (+ or -) may be given instead of a letter grade. The YDS also rates just the hardest move on a climb. The 5th class decimal system was developed in the 1950's in Yosemite Valley, where bold climbers pushing new standards, were quickly out growing the old grades of class 1-4. In the 1960’s, 5.9 was the top end of the YDS scale and climbers establishing first ascents were responsible for giving their new climb a rating. Engaged in peer competition and limited by the rating system, first ascensionist gave every difficult climb the rating of 5.9, even if it was the equivalent of a modern 5.11. It was not until the 1970's that a consensus was reached and the YDS was deemed an open ended system and the rating of 5.10 was established. Routes that were established in that era are still rated by the original rating of 5.9 and continue to cause many unaware climbers problems.