Gear and Carabiners

The Accessories You Need to Climb Effectively:

Harnesses

Harnesses make hanging from the rope comfortable by distributing your weight over a larger surface area, reducing the pressure where it contacts you.

$pressure = \frac{force}{area}$

Minimum Comfort:

This minimalist harness is designed for alpine climbers who are willing to sacrifice comfort for lightweight. Its thin waist belt and leg loops make it less comfortable to hang in than bulkier harnesses.
Straps on minimum comfort harnesses are a lot slimmer and lightweight looking with fewer buckles.

Maximum Comfort:

This harness is made for big-wall climbers who often spend days or weeks hanging in their harness.The thick waist belt and leg loops make it very comfortable to hang in.

Chalk

Chalk is the chemical magnesium carbonate (MgCO3). Climbers often apply it to their hands to keep them dry so that they can grip the rock. Chalk can absorb the sweat your hands create, keeping them dry and maintaining good friction with the rock.

Magnesium
12
Mg

Carbon
6
C

Oxygen
8
O

Shoes

Climbing shoes are designed to give climbers an advantage. The rubber on the soles and around the toes is specially formulated to increase the coefficient of friction (μs) between the rock and shoes.

$F = μ_{s} \times N$

The rubber on the soles and around the toes increase the coefficient of friction between rock and shoes. Increases in frictional force helps the climber stand on his feet and remove weight from his hands. — **Figure 43:** Diagram showing the friction force between rock and shoe.

Note: Increasing $μ_{s}$ increases the frictional force that helps the climber stand on his feet and remove weight from his hands.

Carabiners

Carabiners are a simple and convenient means of attaching ropes, slings and other pieces of equipment to each other.

Parts of a Carabiner

A carabiner is a D-shaped or oblong metal ring with one spring hinged side (gate) and where it connects to (the nose). The spine of a carabiner will usually show the kN rating engraved suitable for rock climbing. — **Figure 44:** Carabiner showing that Major Axis = 22 kN; Minor Axis =7 kN; Open Gate = 5kN

Strength Ratings

Most carabiners are stamped with strength ratings that designate Major Axis, Minor Axis and Open Gate strengths.

Major Axis = 22 kN

Major axis carabiners are loaded going lengthwise and are the strongest orientation.

Minor Axis = 7 kN

Minor axis carabiners are loaded going sideways.

Open Gate = 5 kN

Open Gate carabiners are loaded while open.

Why the Notch?

Carabiners have a notch or similar feature at the nose to distribute some of the load across the gate. This makes carabiners inherently stronger and allows manufacturers to use less material.

Factory of Safety.

The ratio that describes how much stronger a part or a system is than what it actually needs to be for its intended application.

Minor Axis: 20 kN
Major Axis: 5 kN (an average lead climbing fall)

$FoS = \frac{breaking load}{applied load} FoS = \frac{20 kN}{5 kN} = 4$

Most climbing carabiners have a strength above 20 kN. Theoretically, this means they are strong enough to support a full-size pickup truck, even though forces of that magnitude are almost unattainable while climbing.

**Figure 45:** A truck being supported by a single carabiner that has a minor axis strength of 22kN making it able to be supported.

= 22 kN
~ 4,945 pounds
Curb Weight: 4,930 pounds

= 22 kN
~4,945 lb
Curb Weight = 4,930 lb
$FoS = \frac{4, 945 lb}{4, 039} = 1.2$

With a safety factor barely larger than 1, if a small amount of weight were added to the truck the carabiner would break.