The Yosemite Decimal System

The Yosemite Decimal System is a set of numeric ratings describing the difficulty of climbs. It is not the only rating system used by climbers, but it is the one preferred by most of the people who use Climber.Org. According to two contributors, the european rating system is less useful because it is too subjective and the alaskan rating system is more useful because it is less subjective.

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Five classes of climbing difficulty

The Yosemite Decimal System consists of five general classes, the fifth being subdivided with a decimal notation, but it is generally accepted that some ratings are
too high or too low because people want to brag or because the standards among climbers has changed over time, and many people have editorial comments about the YDS.

The class of a route is derived from its "crux" or hardest move. If you hike a class 2 trail from point A to point B, and are required to scale a 20 foot wall of rock (class 4) along the way, then you hiked a class 4 trail regardless of the normal exposure.

The argument that exposure has nothing to do with the class of the climb is not supported by the history of YDS. Exposure was implied in the definition of 4th and 5th class by the use of a rope. Starting in the 5th edition of Freedom, exposure was included in the class descriptions, probably because of the wide variety of techniques being used on the same climbs. In the 6th edition of Freedom, the wording has changed again.

Here are the five classes, where each bullet represents a different opinion as to what the class actually represents. When you are reading a route description or trip report, keep in mind that there may not be general agreement on ratings. The astonishing thing about the email discussion which prompted this expanded definition is that almost everyone thought that almost everyone ELSE agreed with them!

class 1 (used for some peaks that do NOT have trails)

class 2

class 3

class 4

class 5

class 6 (not actually part of the YDS)

Editorial comments on the YDS classes

Hal Murray editorializes:

Steve Eckert editorializes: Andy W editorializes: James Schaffner editorializes: Eric Beck quotes Joe Kelsey, author of the Wind River guidebook: RJ Secor quips:

Quoting Tom Patey: "A solo climber: a man who falls alone. A roped team: climbers who fall together."

Subdivisions of class five climbing

In Mountaineering, Freedom of the Hills, author Ed Peters explains the subdivisions of class 5:

"The experienced climber, having accomplished or attempted free climbs of varying degrees of difficulty in the YDS class 5 range, gains an understanding of the level of difficulty involved. To the beginner, however, these ratings are simply a set of numbers, understandably, easy if rated 5.0 and impossible if rated 5.13. To provide a slightly better understanding within the class for the beginner the following tongue-in-cheek description is provided:

5.0 to 5.4
There are two hand- and two footholds for every move; the holds become progressively smaller as the number increases.
5.5 to 5.6
The two hand- and two footholds are there, obvious to the experienced, but not necessarily so to the beginner.
The move is missing one hand- or foothold.
The move is missing two holds of the four, or missing only one but is very strenuous.
The move has only one reasonable hold which may be for either a foot or a hand.
No hand- or footholds. The choices are to pretend a hold is there, pray a lot, or go home.
After thorough inspection you conclude this move is obviously impossible; however, occasionally someone actually accomplishes it. Since there is nothing for a handhold, grab it with both hands.
The surface is as smooth as glass and vertical. No one has really ever made this move, although a few claim they have.
This is identical to 5.12 except it is located under overhanging rock."

Ratings are established on lead; the follower has a somewhat easier climb.

Don't believe every climbing rating

In Mountaineering, Freedom of the Hills, author Ed Peters warns against putting too much faith in published ratings:

The Angeles Chapter Rating System

The Sierra Club's Angeles Chapter Safety Committee has established classifications for outings that involve different levels and areas of skill but do not relate to the strenuousness of the outing. Very generally, I trips are Class 2, M trips are Class 3, E trips are Class 4-5, but there are many exceptions.
Cconcessionaire For events under external control of a non-Sierra Club entity.
(e.g., ranger, concessionaire)
Oordinary Applies to uncomplicated outings such as hikes on trails or equivalent.
Iintermediate Includes outings involving off-trail travel that require navigational skills.
Mmoderate Applies to outings that include moderate snow climbs and/or class 3 rock climbing.
Eextreme Applies to outings that involve more severe snow climbing.
Ttechnical Applies to outings that involve specialized technical activities.
(and will usually be combined with one of O/I/M/E)

The European Climbing Scale

From: Karl Habermeier
Date: Wed, 23 Aug 2000 17:00:08 -0400

That's in fact how the old European I to VI scale defined it:
  I:    Easy
  II:   Not difficult
  III:  Moderately difficult
  IV:   Difficult
  V:    Very difficult
  VI:   Extremely difficult

This is of course highly descriptive and informative. Grade I corresponds to
U.S. class 2-3, and Grade VI is about 5.9, with the rest of the ratings
falling somewhere in between. The scale has since of course been extended
upward to VII, VIII, IX, etc. corresponding to the higher U.S. difficulties
5.10 and up. No names have been given to most of these, as far as I know
(such as "super difficult".

But I agree with some of the earlier writers that defining class 4 is the
most trouble. At least one earlier Sierra guidebook rates the summit block
on Cathedral Peak as class 4. 

The Alaskan Climbing Scale

From: Steve Eckert
Date: Mon, 21 Aug 2000 20:09:15 -0700

I prefer (but don't use because no one who climbs with me uses) the
Alaskan rating system, which doesn't pay any attention to anything
except the specific techniques needed:
   class 1: can be done with wheels (may still include boulder hopping!)
   class 2: can be done without using hands (maybe SHOULD, but don't HAVE TO)
   class 3: "climb as a child" - no counterforce, vertical pull with hands only
   class 4: real climbing with counterforce - stemming, laybacks, jams, etc
   class 5: weight is put on the rope - aid climbing
Note that only class 5 is defined by the use of a rope. In all other
cases it's up to the climber whether one is needed. Routes are described
as "loose class 3" or "exposed class 2", with modifiers to describe all
the things that get lumped into the one Yosemite number.