How to tie it
- 1Lay the two poles side by side and start with a clove hitch around one pole, near the end where you want the pivot.
- 2Make wrapping turns around both poles — enough that the band is at least as wide as the two poles together. Snug, but not so tight the legs can't pivot open.
- 3Make frapping turns (at least two) between the poles, around the wraps, to tighten the band.
- 4Finish with a clove hitch, traditionally on the other pole from where you started.
- 5Spread the free ends apart to open the shear legs into an A-frame.
When to use it
- Shear legs / A-frames for lifting loads, anchoring a rope bridge, or forming the uprights of a gateway.
- Simple cranes and levers in pioneering projects.
- The legs of trestles and hinged supports for walkways and bridges.
- Extending a pole end-to-end is the confusingly-named cousin — usually a round lashing, not a shear lashing.
Common mistakes & safety
- Shear legs carry real load and can fail catastrophically. Inspect poles for cracks and rot, size the rope to the load, and keep people off and out from under the structure until it's checked and guyed.
- Tight enough to hold, loose enough to open. Too loose and the legs splay and collapse; too tight and you can't set the angle. Set the spread, then anchor the feet.
- Stop the feet from spreading under load. A rope or stake across the bottom — or the ground itself — keeps the legs from sliding out.
- Lock the start and finish clove hitches. If either slips, the whole band loosens.
- Match the joint to the job. Parallel poles = shear lashing; crossing poles = square or diagonal lashing; extending a pole end-to-end = round lashing.
Going deeper
- Shear vs. round vs. square. A shear lashing binds two parallel poles for shear legs; a round lashing binds two parallel poles to extend them end-to-end; a square or diagonal lashing binds two crossing poles. The overlapping names cause real confusion.
- The magic is the pivot. Because the poles are bound at only one point, they hinge — and that hinge is what lets flat-lashed poles open into a rigid triangle once the feet are anchored.
- Two legs or three. Lash three poles the same way and spread them into a tripod (gyn) — an even more stable lifting and standing structure.
Official source
Shear Lashing on Knots3D →Pioneering methods and official wording live with Scouting America. Confirm the current technique and safety guidance at scouting.org before building anything people will climb or stand on.