https://matteocampagna.com/en/registry/equipment/spine-varies-around-shaft Changes to this claim in Matteo Campagna's evidence registry: its status, its year-by-year history, revisions of the page. en-gb https://matteocampagna.com/en/registry/equipment/spine-varies-around-shaftThe measurement exists, and there is only one, but it was done carefully. On 59 Easton X10 shafts of spine 325, tested on an automated rig that bends them at every sixteenth of a turn for at least four full turns, 64 measurements per shaft, stiffness almost always follows the same wave: two maxima and two minima per turn, that is a strong axis and a weak axis. The difference is small, on average 0.014 mm of deflection out of about 8.3, ranging from a thousandth of a millimetre, practically nothing, up to 0.038; a few shafts show a slower, different wave, which the authors read as a possible manufacturing or batch defect. Shot at 70 m by a machine, the shafts with the widest wave land further right, while the position of the vanes relative to the stiff side moves nothing measurable. That shafts have a stiff side is therefore documented, on a single arrow model and one of the stiffest spines, but in some of them the difference is negligible, and the idea that the anomalous wave in a few shafts is a manufacturing defect, to be weeded out in selection, remains the authors' interpretation.claim:spine-variabile-attorno-asta:revision:2026-06-23:2Tue, 23 Jun 2026 08:00:00 GMT https://matteocampagna.com/en/registry/equipment/spine-varies-around-shaft#storiaA Korean study shoots the same arrow three times by machine, turning the nock 120 degrees between shots, and finds impacts lying from under two millimetres to two centimetres from their centre, depending on the arrow. The design is the one that would reveal a stiffer side, but stiffness around the shaft is not measured and the spread is not attributed to any cause: no one has yet measured whether a shaft's stiffness changes as it is turned, and the status stays not studied.claim:spine-variabile-attorno-asta:history_entry:2026-06-23:2016Tue, 23 Jun 2026 08:00:00 GMT https://matteocampagna.com/en/registry/equipment/spine-varies-around-shaftclaim:spine-variabile-attorno-asta:new_claim:2026-02-28:riportatoSat, 28 Feb 2026 08:00:00 GMT