On a recurve there is no single right centreshot or button tension, but a range
2 studies
The summary today
Everything known comes from models. In 1997 a model of the archer's paradox had described the arrow's double contact on the button, one brief and light and one long and strong, without asking the question. In 2012 a model of the recurve in the lateral plane, checked against photographs of the arrow during the power stroke and against a shooting machine that sends the arrow to the same spot as the archer, looks for the best setting and does not find one: moving the centreshot from zero to two millimetres calls for a change from 163 to 166 newtons of draw weight to keep an arrow that leaves without rotation, and raising the button preload from 3.5 to 5 newtons calls for a change from 164.5 to 168. The settings, in other words, offset one another, and within a reasonable range several combinations give good flight. The model adds three details: no combination cancels rotation and angle of attack together, so it is better to tune for zero rotation and accept a small residual angle; with a slightly negative centreshot the arrow's first light contact on the button disappears; a softer button damps release errors a little, but if it is too soft it gives multiple contacts and widens the group. Nobody has yet changed centreshot and button in steps, on a machine or with archers, while measuring the group, so how wide the range is on the target remains unknown.
Also phrased as: "centreshot setting"; "button tension"; "plunger preload"; "optimal centreshot"; "tuning a recurve with the button"
In practice
Tuning a recurve is often treated as a search for the right centreshot and the right button tension, as if there were one exact value to find and every departure from it showed up in the group.
Evidence
-
1997
Context Model Published later
A model of the archer's paradox with the measured parameters of a real button (spring constant 622 newtons per metre, minimum force 3.3 newtons, maximum 7.65, travel 7 millimetres): just after the release the arrow touches the button with a small force and leaves it quickly, then touches it again for longer and with a much larger force, and comes free of it while the string is still pushing it. It describes the contact; it does not look for a best setting of centreshot or button.
On the mechanics of the arrow: Archer's Paradox · B.W. Kooi, J.A. Sparenberg
-
2012
For Model Published later
Model of the recurve in the lateral plane, with the button represented as a preloaded spring, checked against photographs of the arrow during the power stroke and against a shooting machine: as the centreshot changes so does the draw weight needed for zero rotation after separation, but no centreshot turns out to be preferable. Moving it from zero to plus two millimetres calls for a change from 163 to 166 newtons; raising the button preload from 3.5 to 5 newtons calls for a change from 164.5 to 168. The author concludes that no choice of parameters proved optimal and that, within a reasonable range, several settings give good flight. No combination, moreover, gives zero angle of attack and zero rotation together: with the bow tuned for zero rotation a residual angle of attack of about 0.7 degrees to the direction of the centre of mass remains, and the author advises accepting it, since it gives better flight.
Arrow behaviour in the lateral plane during and immediately following the power stroke of a recurve archery bow · James L Park
-
2012
Context Model Published later
The range has two edges. With a slightly negative centreshot the arrow's small initial force on the button vanishes, which the author points to as a possible disadvantage. Lowering the button's spring constant and preload makes a variation in the way the string leaves the fingers shift the arrow on the target slightly less; with very light settings, though, the arrow touches the button several times and the errors on the target grow. The button helps absorb technique errors without ever cancelling them completely, and the model gives no figures for this effect. In the same model the arrow presses on the button only in a window of a few milliseconds at the start of the power stroke: a very light contact up to 1.5 milliseconds, not enough to push the button in, then nothing until 3.2, because of the second bending mode, and the main pressure between 3.2 and 7.0 milliseconds. It explains why centreshot and preload act on the tune like a few newtons of draw weight.
Arrow behaviour in the lateral plane during and immediately following the power stroke of a recurve archery bow · James L Park
Status history
- 1997 Not studied A model of the archer's paradox, with the measured parameters of a real button, describes how the arrow touches it: a brief, light contact just after the release, then a longer and much stronger one, over before the arrow leaves the string. It is the mechanism that centreshot and button act on, but nobody has yet asked whether there is one best setting or a range of settings that work.
- 2012 Transferred The first answer comes from a recurve model checked against photographs and a shooting machine. In the model a centreshot from zero to two millimetres calls for tuning draw weights between 163 and 166 newtons, and a button preload between 3.5 and 5 newtons calls for 164.5 to 168: the settings offset one another and several combinations give good flight, with no optimal value. No combination cancels rotation and angle of attack together, with a slightly negative centreshot the first contact on the button disappears, and a button that is too soft gives multiple contacts and widens the group. It is all calculation, with no measurement on the target: transferred.
Related
Related articles
- The parts of an Olympic recurve bow, one by oneThe parts of an Olympic recurve bow, from riser and limbs to arrow rest and clicker: what each one is called, what it does and what the rules allow.
- Bow tuning in archery: how to tune your bow, backed by scienceBow tuning and the research: spine, centre shot, button, nocking point, brace height and tiller. What models and machine tests show, and how precise you need to be.
- First adjustments to your bow: what to set and in what orderBrace height, tiller, nocking point, centreshot and pressure button, sight marks: what each one is and the order in which to set them on a new bow.
Research lines
Cite
Campagna, M. (2026). On a recurve there is no single right centreshot or button tension, but a range (Version 3). In Evidence Registry. Retrieved 16 October 2026, from https://matteocampagna.com/en/registry/equipment/centreshot-and-button-tension-range
@misc{campagna2026_centershotbottoneintervallo,
author = {Campagna, Matteo},
title = {On a recurve there is no single right centreshot or button tension, but a range},
year = {2026},
howpublished = {Evidence Registry, matteocampagna.com},
url = {https://matteocampagna.com/en/registry/equipment/centreshot-and-button-tension-range},
note = {Version 3; accessed 2026-10-16}
}
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