I second brenta, and can't figure out why people keep calling this triaxial loading. None of the forces appear to be TRIaxial loading.

It may be a matter of semantics, but triaxial loading sounds right to me because there are three separate force vectors acting on the biner. Although each one is on the same plane, they each pull in an independent direction, each on its own axis.

Some of you keep insisting that we stop being know-it-alls, and take the advice of the manufacturers. Here is a safety note from Tom Jones, at Black Diamond:

From: Tom Jones at Black Diamond - There has been a lot of chat recently about the use and limitations of harness belay loops. I would like to lay out the thoughts behind and uses for belay loops as we have found through use and testing.

History

Belay loops were invented about 10 years ago to solve the problem of having no obvious place to clip into a harness for belaying and rappelling. Some bright guy thought of making a stout webbing runner, that the structural parts of the harness would pass through, that would then stick out in front and be easy to use. The idea caught on because many people found it convenient. Some harnesses do not allow for the use of a belay loop due to geometric constraints.

Design Constraints

A harness is designed to catch falls either as the faller or as the belayer. The maximum loads felt by a faller are suspected to be at most 15 kN ( 3372 lbs ). This is the load at which other parts of the system start breaking, such as the rope at the tie in knot, the top biner through the protection, and the faller's body being broken by the forces of de-acceleration. Thankfully, very few falls reach forces anywhere near this high, but we can view it as an upper limit.

Can this force be felt by a belayer too ? You bet. The worst case fall is where the leader does not get any pieces in, then pitches off and falls directly on the belay. Climbers are usually smart enough to clip the lead rope into a draw on the anchors, so that the belayer experiences an upward force, but this is not always the case. The leader could fall directly on the belayer with no intervening pieces so the belay loop system must be able to hold that 3372 lbs of force.

This brings up why it is important to clip your belay device into both your belay loop and the loop of the rope on multi pitch climbs. The lead rope should be your primary anchor - your primary link from your harness to the anchor - because it is dynamic and flexible. Your belay biner should connect directly to the rope tie in loop so that the forces of the belay can link directly to the anchor. Otherwise, the forces from a severe fall would run from your belay biner to the belay loop, to the harness, to the rope loop to the anchor. This would tend to rip the harness apart and the results are very unpredictable. It is much better to have the forces transfer as directly as possible to the strong point in the system - your fully equalized, three bomber pieces anchor. Wear and Tear

So if the belay loop is so strong, why don't I tie into it? Because you would wear it out very fast. The established tie in points on harnesses are usually covered with a durable cloth or webbing to take the brunt of the abrasion from the rope being tied in. Falls, hanging and hangdogging tend to move the rope slightly, under load, against the harness, and this results in a lot of abrasive wear. If you subjected the belay loop to this wear, it's unprotected webbing would wear out pretty quickly.

In belaying, the situation is a little different. The belay biner has a lot less friction so it slides to the top of the loop right away. There is very little webbing on webbing sliding. Belay loops do fuzz up a little from the forces of the biner, but not very fast. It helps that belay forces are usually much less than falling forces.

No Belay Loop Harnesses

Many harnesses do not have a belay loop, usually because of geometric constraints. Is it safe to belay off a carabiner clipped through both the waistbelt and leg loop?

On first look, you might think this is a classic case of triaxial loading of a carabiner - a definite no-no. At some modest load, however, the belayer's body will change position and the harness webbing will stretch so that the bottom of the belay carabiner gets loaded correctly. The load required to do this is pretty low, probably lower than the 6 kN side loading strength of a weak 'biner.

The greater danger is that the carabiner will get stuck on something or that the gate will get stuck open by webbing or a piece of clothing. We have all experienced the locking sleeve getting stuck on something while belaying, and this could be dangerous. I got my finger pinched once when I was straightening out my belay biner at the point of impact. Ouch!

I have seen returns from where the locking belay biner was not fully closed when loaded. I think they got stuck in the climber's clothing, but the climber insists that the gate was closed and locked. Maybe the first instance of a gate pin tunneling out the end of the biner.

Without a belay loop, it is VERY IMPORTANT to have the belay forces transfer directly to the anchor, on a multi-pitch climb. I usually belay off my tie in loop, essentially using that as a belay loop.

Summary

The belay loop is designed for rappelling and belaying only. Use it if you find it convenient. If you tie the rope directly into it, you will wear it out very quickly. On multi-pitch climbs, it is important to have the forces of the belay link directly through to the anchor, usually by clipping the belay biner into both the belay loop and the tie in loop of the webbing.

Understanding the forces involved in climbing is helpful in climbing safely. Understanding the limitations of your gear is essential.

As I have said several times now: It is perfectly acceptable to belay from your tie-in points. The more important factor is to understand the limitations of your equipment and to make your decisions based on experience, product knowledge, and common sense.

There is usually more than one right way to do things, and many wrong ways. It is up to the individual, before tying in, to understand and assess his or her best and safest options, and, more importantly, to understand the potential consequences of neglecting to do so. If you find two safe ways to rig something, and one of them feels more secure to you, then go with that one, because feeling insecure about equipment inhibits your ability to focus on the more important tasks at hand.

In a fall, would a biner through the leg & waist loops be detrimental toward arresting that fall?

As I see it the harness loops will group together and the biner & loops will orient to the spine. What would be more a problem is belaying directly off your anchor then also clipping into your harness. I could see higher probability of a crossload here.

What might be a problem by using only the harness loops is having them open the gate and then losing the biner circle strength, also Kevin pointed out the rope could ride the gate to open and damage the rope & also lose the biner circle.

Carabiners can break when cross-loaded, or when loaded with the gate opened, I've had it happen several times now and watched the lab tests, it does happen.

Also mentioned from Gadd's input was friction close to the harness - "heat sink" & probability of catching clothes & hair in the device. With cow-tailing a rap this pretty much takes that away, so I don't always use my belay loop, but I do for lead belaying.

good post Ken; sorry, I was writing some thought when you posted. They look somewhat similar.

Beer? anyone??? Anyone here like beer?

can't stand the stuff. especially that dark stuff, Guiness & Murphys, uugggghhh, please no. In the words of the almighty Shrek: "Can't we just settle this over a pint?"

I use my belay loop. A lot of my partners still clip to their tie-in points. I never say anything because, as we see here, rarely will you change people's minds about their chosen method.

Someone pointed out that they are more comfortable belaying one way vs. another due to time logged in that set-up. It's true that the body creates strong patterns of motor memory for regularly-performed movements. So perhaps asking my belayer to switch on the fly (if they would actually do so!) might mean I would get a less competent belay right then! (I'm only theorizing.)

On another note, for those who feel their biners are unlikely to get cross-loaded when clipped through the tie-in points: I have personally witnessed cross-loading occur on the gate during belaying with this method. Because I was standing by the belayer, I quickly noted to them their orientation. So I believe it's a good idea to keep an eye on your set-up no matter which method you use.

As someone else also said, the best insurance is an attentive belayer.