Flagging: stop the barn door before it starts

Why you swing off

You reach for a hold, your hand lands, and then your whole body pivots away from the wall like a door swinging open on a hinge. That is the barn door, and it is one of the most common ways climbers come off, especially on vertical and slabby ground. It happens when your points of contact are stacked on one side of your body. With a hand and foot both on the left, say, there is nothing on the right to balance against, so the moment you move, your right side swings out and pulls you off.

The fix is not to grip harder. It is to put something on the other side. That something is usually a leg, held out into space or pressed against the wall, and using it that way is called flagging.

The outside flag

An outside flag is the workhorse. Imagine you are reaching up with your right hand off a right foot, and there is no foothold for your left foot. Instead of leaving the left leg dangling, you extend it out to the right, crossing behind, and press the inside edge of that shoe against the wall or just hold it out as a counterweight. That extended leg balances the swing and keeps your hips square to the rock.

You will feel it work immediately. The reach that was throwing you sideways suddenly goes calm and static, because your body is balanced over the foot you are standing on rather than rotating around it.

The inside flag

The inside flag is the same idea from the other direction. Here you tuck the free leg across in front of your standing leg and press it against the wall to stop the rotation. It is useful when the wall or the holds do not give you room to swing the leg out wide, or when the natural body position has your free leg already crossing in front.

In practice you do not need to memorise which is which. The principle is what matters: when you feel a swing coming, stick a leg out to oppose it, on whichever side stops the rotation. With a bit of practice you will reach for the right one without naming it.

Reading when to flag

The cue to flag is mismatched contact. Look at your stance before a move and notice when your hand and foot are on the same side with nothing on the other. That is a barn door waiting to happen, and a flag is usually the answer. A few common triggers:

• A long reach off a single foot with no foothold for the other leg.
• Moving up on holds that are all stacked towards one side of your body.
• Any move where you feel your hips wanting to rotate as you reach.

Get into the habit of asking, before you commit, whether your body is balanced or stacked. If it is stacked, find a flag.

Drilling it

Flagging feels deliberate and slow at first, then becomes invisible. The way there is reps on easy ground. Pick a slab or a vertical wall a couple of grades below your limit and climb it with one rule: your free leg is never allowed to just hang. Every time it is not on a hold, it flags somewhere, out wide or across the front, to keep you square.

You will be surprised how often that is, and how much steadier you feel. Before long you will stop swinging on your projects without ever consciously deciding to flag, which is the sign it has become part of how you move.