Compare Methods
Make the final call
This page doesn’t teach the methods — the method guides do that. It’s for the moment you’ve read enough and need to choose.
Quick recommendations
Category winners with the caveats attached. Where supporting data is incomplete, the recommendation says so.
Simplest practical solution
Cord, anchors, done. Accept the linear force profile and routine re-tensioning.
GuideLowest-cost solution
A few dollars of cord. Constant-force springs are the next rung up in both cost and capability.
GuideHighest force accuracy on a continuous lift
Per-stage ratings track the stepped load; accuracy is limited by catalog rating steps.
GuideLowest manufacturing burden
Fully COTS. Constant force follows if you have a 3D printer for spools.
GuideBest offseason experiment
The most engineering learning per project — and the least schedule-safe in season.
GuideBest for stage-specific compensation
The only method whose COTS parts naturally deliver a different force per stage.
GuideBest when the slide envelope is packed
Moves all counterspring hardware to the winch — provisionally recommended; verified reference builds are lacking.
GuideComparison matrix
Fourteen criteria across all four methods. Click a criterion to expand the reasoning behind every rating in that row.
| Criterion | Bungee | Constant Force | Constant Torque | Sprung Linkage |
|---|---|---|---|---|
| Linear, increasing with extension | Nearly constant per spring; stepped per stage | Nearly constant (single level)est. | Custom — designed by geometry | |
| Approximate, level 2 of 5 | High, level 4 of 5 | High for one force levelest., level 4 of 5 | Potentially excellentest., level 4 of 5 | |
| Low, level 1 of 5 | Moderate, level 3 of 5 | Elevatedest., level 4 of 5 | High, level 5 of 5 | |
| Lowest, level 1 of 5 | Moderate, level 3 of 5 | Moderate–highest., level 4 of 5 | Low parts, high effortest., level 2 of 5 | |
| Light, level 2 of 5 | Moderate, level 3 of 5 | Concentrated at the winchest., level 3 of 5 | Demandingest., level 4 of 5 | |
| Minimal, level 1 of 5 | 3D printing + basic assembly, level 2 of 5 | Machining or careful printingest., level 3 of 5 | Custom fabricationest., level 4 of 5 | |
| Iterativeest., level 3 of 5 | Select, then verify, level 2 of 5 | Design-timeest., level 3 of 5 | Highest., level 5 of 5 | |
| Recurringest., level 4 of 5 | Lowest., level 2 of 5 | Low (expected)est., level 2 of 5 | Pivot wearest., level 3 of 5 | |
| Good if maintainedest., level 3 of 5 | High once verifiedest., level 4 of 5 | Unvalidated in this guideest., level 3 of 5 | Depends on executionest., level 3 of 5 | |
| Moderate stored energy, level 2 of 5 | Sharp edges, snap-back, level 3 of 5 | High stored energy, level 4 of 5 | Pinch points + stored energy, level 3 of 5 | |
| Good, level 4 of 5 | Excellent, level 5 of 5 | Workableest., level 3 of 5 | Possible, complexest., level 3 of 5 | |
| Goodest., level 4 of 5 | Workableest., level 3 of 5 | Goodest., level 4 of 5 | Goodest., level 4 of 5 | |
| Low–moderateest., level 2 of 5 | Moderateest., level 3 of 5 | Elevatedest., level 4 of 5 | Highest., level 5 of 5 | |
| Common | Established | Rare | Uncommon for lifts |
Cells marked est. are editorial estimates awaiting experimental data. Click any criterion to read the reasoning.
Interactive force-curve comparison
All four force models against the same lift. Toggle methods, switch between continuous and cascade, adjust masses and spring parameters, and view the matching error directly.
Force-curve comparison
Illustrative models, not measured data
Bungee
Constant force
Constant torque
Sprung linkage
Experimental results
The controlled head-to-head test this comparison ultimately deserves. The protocol and metrics are defined; the data is not yet collected, and the table stays empty until it is.
Controlled test results
No data collected yet| Metric | Baseline (no spring) | Bungee | Constant Force | Constant Torque | Sprung Linkage |
|---|---|---|---|---|---|
| Extension time(s) Full travel, timed from video at 120 fps, median of 5 runs | — | — | — | — | — |
| Retraction time(s) Full travel down, same protocol | — | — | — | — | — |
| Peak current(A) Logged at 50 Hz during extension | — | — | — | — | — |
| Average current(A) Mean over a full extend–hold–retract cycle | — | — | — | — | — |
| Holding current(A) 10 s hold at half and full extension | — | — | — | — | — |
| Maximum acceleration(m/s²) From encoder velocity trace | — | — | — | — | — |
| Position overshoot(mm) Step command to half extension | — | — | — | — | — |
| Motor temperature rise(°C) After 20 consecutive cycles, IR thermometer on the case | — | — | — | — | — |
| Battery voltage sag(V) Minimum bus voltage during extension from 12.5 V start | — | — | — | — | — |
| Manual breakaway force(N) Luggage scale, force to start the lift moving unpowered | — | — | — | — | — |
Protocol: all methods tested on the same lift and battery, with repeated trials (n ≥ 5) and at least two payload variants (bare carriage and carriage + game-element mass). Thermal and cycle testing follow the per-method testing sections.
Every value on this table will link to its raw trial data. Until then, the table stays empty rather than illustrative — no fabricated numbers.
Decision summary
Work down these five questions in order — most teams are done before the list is:
- Team capability. COTS-only teams: bungee is the honest choice. A 3D printer unlocks constant force. Full fabrication plus mechanism-design experience unlocks the advanced pair.
- Robot requirements. Need float-anywhere holding on a continuous lift? That’s constant force per stage. Need a rough assist to tame current draw? Bungee covers it. Cascade lift? Any constant-force-profile element works — pick by packaging.
- Competition timeline. In season, adopt only well-documented methods you can revert quickly: bungee first, constant force second. Constant torque and sprung linkages are offseason projects until the community documents them better.
- Acceptable complexity. Every spring, spool, and pivot is a part that can fail in a match. Choose the simplest method that solves your measured problem — and remember “none” is a valid answer.
- Desired performance. If the goal is a measurable current or speed win, define the target number first, instrument the lift, and let the testing protocol tell you whether the method you chose delivered it.
Still undecided between two? Work through the Selection Considerations with your team, then read both guides’ “Avoid this when” columns — disqualifiers decide faster than advantages.