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While it drives the arrow a compound bow rotates in the vertical plane, and no position of its centre of mass cancels that rotation

2 studies · 1 archers measured

ForContextAgainst20102015202020252009, context, n = 12010, for2010, context
Each circle is a study: its position gives the year, its row whether it is for, against or context, its size how many participants it measured. Light circles are studies on other populations or without archers.

There is a single piece of work, from 2010, and it is a dynamic model of the compound bow. According to the calculation, during the power stroke the bow rotates in the vertical plane and the direction depends on the cams; the authors state in one sentence that they checked this with accelerometers mounted on the riser, but the measured data are not published and the paper does not say whether an archer or a machine was shooting, so the registry reads it as a model. On a single-cam compound the top limb moves away from the archer, because the cam at the bottom and the wheel at the top have different inertias; on a hybrid-cam bow the rotation is the other way round, and the main cause is the reaction from the string pushing on the arrow, which sits above the grip. The same model shows that no position of the bow's centre of mass can bring the rotation to zero, because some of the moments involved are constant while others follow the force on the arrow and the speed of the cams, with different profiles over time. Two things limit the picture: the resulting movement of the nocking point is small compared with the one produced by the geometry of the cams, and the part about it being impossible to cancel is an argument from the model, not a test carried out by moving weights on the bow. That is why the status is "Transferred". On the recurve there is only, from 2009, the aim of a single archer recorded with a laser on the grip: it shifts during the release, but the measurement does not separate the movement of the bow from that of the hand.

Also phrased as: "the bow rotates at release"; "bow rotation during the power stroke"; "riser rotation"; "single cam and hybrid cam"; "balancing the bow with weights"

In practice

Archers are told that the stabiliser and weights are there to hold the bow still until the arrow has gone, and that a well-balanced bow does not move until the string has finished its work.

Evidence

  • 2009
    Context Archers Published later

    A single archer with a recurve, 32 arrows analysed at 30 metres: a laser on the grip filmed at 1,200 frames per second follows the aim until the arrow leaves, and a model of the aim in the preceding frames predicts where the bow would have gone without the release. The vertical gap between the real and the predicted path in the last frames goes with the height of the impact (r = 0.62 with the vertical error on the target, 0.50 with the distance from the centre), and the more the predicted path rose, the further from the centre the arrow landed (r = −0.52); no p values. The laser follows the bow together with the hand, so it does not separate the bow's own rotation from the archer's.

    Time series analysis during the releasing arrow stage · Kun-Shu Huang, Chi-Kuang Hwang, Kuo-Bin Lin, Chia-Wen Wu

  • 2010
    For Model Published later

    Rotation calculated with the dynamic model and which the authors say, in one sentence and without showing the data, they checked with accelerometers on the riser: on a single-cam compound the top limb moves away from the archer, mainly because of the different inertia of cam and wheel; on a hybrid-cam bow it moves towards the archer, mainly because of the reaction to the string's force on the arrow.

    Compound-archery-bow nocking-point locus in the vertical plane · J L Park

  • 2010
    For Model Published later

    In the model some components of the moment on the bow are constant, while those linked to the force on the arrow and the speed of the cams change with different profiles during the power stroke: for this reason the bow's centre of mass cannot be placed so that the rotation is zero.

    Compound-archery-bow nocking-point locus in the vertical plane · J L Park

  • 2010
    Context Model Published later

    For the single-cam compound, the vertical movement of the nocking point due to the bow's rotation is small compared with the movement due to the geometric path of the cams: the rotation is there, but it weighs little on the path of the nock.

    Compound-archery-bow nocking-point locus in the vertical plane · J L Park

Status history

  1. 2009 Not studied The first measurement close to the question concerns a recurve and a single archer: a laser on the grip filmed at 1,200 frames per second shows that, while the string drives the arrow, the aim moves away from where it would have gone without the release, and that the vertical part of that gap goes with the height of the impact. The laser, though, follows the bow together with the archer's hand, and nobody has yet measured the bow's own rotation during the power stroke, on either the recurve or the compound.
  2. 2010 Transferred The first and only study of the question is a dynamic model of the compound bow: during the power stroke the top limb moves away from the archer on a single-cam bow and towards the archer on a hybrid-cam one, and no position of the centre of mass cancels the rotation, because the moments involved change over time in different ways. The authors state in one sentence that accelerometers on the riser confirm the calculated rotation, but they do not show the data or say who was shooting. With only the calculated part on record, and an effect on the nocking point that is small next to the geometry of the cams, the claim rests on a model: transferred.

Related

Related articles

Research lines

Cite
APA

Campagna, M. (2026). While it drives the arrow a compound bow rotates in the vertical plane, and no position of its centre of mass cancels that rotation (Version 3). In Evidence Registry. Retrieved 16 October 2026, from https://matteocampagna.com/en/registry/equipment/compound-bow-rotation-power-stroke

BibTeX
@misc{campagna2026_rotazionearcospinta,
  author = {Campagna, Matteo},
  title = {While it drives the arrow a compound bow rotates in the vertical plane, and no position of its centre of mass cancels that rotation},
  year = {2026},
  howpublished = {Evidence Registry, matteocampagna.com},
  url = {https://matteocampagna.com/en/registry/equipment/compound-bow-rotation-power-stroke},
  note = {Version 3; accessed 2026-10-16}
}

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