Compound bow tuning device: Yacshie 2026 study

The authors, nearly all from Yogyakarta State University, built a device for compound bows that combines an electric bow press and a manual draw board in a single tool. They assessed it first through expert ratings and then for its effect on shooting. Six Indonesian experts (three professors, one holder of a doctorate and two international coaches) gave the various questionnaire items scores between 86.68% and 89.82% of the maximum, all in the "appropriate" category.

In the trial, 30 compound archers aged 19 to 22, described as elite, were split into 15 treated and 15 controls. Over 16 sessions, three a week, the treated archers' bows were adjusted with the device until they gave a clean hole through paper, then the archer shot 36 arrows at 30 metres. According to the table of the statistical analysis, in the treated group "arrow speed" went from 13.63 to 15.90 and the score from 243.60 to 272.54; in the controls from 13.52 to 14.50 and from 213.70 to 236.23. Another table in the same paper gives different figures for the same measures. The authors conclude that the device increases arrow speed and accuracy.

The project follows the ADDIE model (analysis, design, development, implementation, evaluation), used in research on developing teaching products. Agreement between the experts is reported as an Aiken validity index of 0.904 and an intraclass correlation of 0.948. The device has a frame, jaws that clamp the limbs, adjusting screws, feet, a draw length adjuster, a draw arm and an electric motor that draws and lets down; it works only when plugged into the mains.

The 30 archers were recruited through an online form among those willing to follow the programme, on three criteria: elite or professional level, compound division, and no family ties to researchers or coaches. The split into two groups is described as "ordinal pairing". The instrument given for arrow speed is paper tuning, with no unit of measurement; accuracy is the total of 36 arrows at 30 metres, with no target face specified. Comparisons are paired t-tests, before and after, within each group.

The figures do not hold together. The results table gives the treated group a speed that falls from 13.63 to 10.44 and a score that rises from 296 to 340; the analysis table, for the same measures, gives 13.63 and 15.90, 243.60 and 272.54. The t and significance values for the control group (7.879 and 8.892, with p 0.000) are identical, digit for digit, to those of the treated group. In the discussion, 10.44 becomes an extreme spread of velocity in feet per second, presented as an improvement on the 2.1 fps of conventional paper tuning even though it is five times larger. Speed, moreover, cannot be measured with a sheet of paper, and no chronograph is mentioned.

Even taking the analysis table at face value, both groups improved significantly, and there is no comparison between the groups, which is the only one that could attribute anything to the device. The groups started from different scores (243.60 against 213.70), and we are not told what the controls did or how their bows were set up. Over 16 sessions the archers were training in any case, and the improvement in the controls suggests that part of the effect comes from that. The conclusion even refers to "children's" arrows, which play no part in the study.

For compound archers, the paper gives no grounds for saying that a press with a built-in draw board gives faster arrows or better accuracy. What remains is something anyone who sets up and tunes their own bow already knows: having the press for changing strings and cables, straightening the peep or timing the cams, and the draw board for checking the bow at full draw, in a single tool saves time. The authors also advise pressing only on the limb tips, never on the riser or near the cams of parallel-limb bows, which is guidance on using presses rather than a finding of the study.

As for speed and score, the tables contradict each other and the control group also improves significantly: for now these figures say nothing about the effect of the device.