System: Winner over further, sprinting at a stiff track

Mechanism and rationale

At a track with a stiff uphill finish a sprint is run like a longer race. A horse whose last win came over at least a furlong and a half further looks to be dropping to a trip too short for it; the hill turns its stamina into finishing speed. It has won half as often again as its prices implied in every period since 2020, at long prices: it pays at Betfair SP and about breaks even at bookmaker SP.

The rule

race_type = 'Flat' AND distance_yards <= 1340 AND track_stiff_finish = 1 AND last_win_distance_yards >= distance_yards + 330

Reads: race_type, distance_yards, track_stiff_finish, last_win_distance_yards

Pre-registration

Spec hash (sha256 of the canonical pre-spec)

not designed yet

Frozen

not frozen

The definition can still change.

Backing

exchange

Kind

system

Live from

2026-10-13

Matched

{
  "hypothesis_id": "H181-proven-over-further-at-a-stiff-track",
  "similarity": 0.6,
  "variant": "Flat, six furlongs or less"
}

Published

true

Rules

• The race is on the Flat over six furlongs or less, at a track with a stiff finish.
• The horse's most recent win came over at least a furlong and a half further than today's trip.

Source

Stamina and track analysis, October 2026

System id

stayer-dropped-to-a-stiff-sprint

Tier

none

Where

race_type = 'Flat' AND distance_yards <= 1340 AND track_stiff_finish = 1 AND last_win_distance_yards >= distance_yards + 330

Discovery result

Not measured yet.

Falsification

No attacks yet. Only promising ideas are attacked.

Sealed holdout (vault)

Not queried. Only a frozen idea can spend its one query against the 2020-25 holdout.

Forward record

No forward record. Shadow tracking starts after the vault and counts only races run after the freeze.

Lineage

Agent runs

• investigator v1ok · 45s · 16 Oct, 12:40

  Output (schema-checked)

  {
    "reflection": "This thread has one result so far, and it is solid. Horses whose last win came at least 330 yards (a furlong and a half) further than today's trip, running at a stiff-finish track, scored A/E 1.08 on 9,279 bets. The figure held across all three periods (1.06, 1.07, 1.12), with 1.068 on 7,574 at discovery. The best segment was Flat races of six furlongs or less: A/E 1.51 on 303 bets, now the live system SYS-stayer-dropped-to-a-stiff-sprint. Two things keep this short of understood. First, BSP ROI is +19% against SP ROI of -14.5%. A gap that wide often means the profit sits in longshots, where BSP pays well above SP, so the price-band split matters. Second, the 1.51 sprint figure is the best of several segments, so it is probably flattered by having been picked. Nothing yet shows that the stiff finish causes the edge rather than the trip drop alone: no test has run the same rule at sharp tracks or checked whether the edge shrinks as the trip gets longer. The two rules also name different columns (last_win_yards versus last_win_distance_yards), which should be checked so the live system really is a subset of its parent.",
    "answers": [],
    "questions": [
      {
        "question": "Does a recent winner over at least 330 yards further beat its price at non-stiff tracks too, i.e. is the stiff finish needed at all?",
        "rationale": "If the trip drop alone carries A/E about 1.07 everywhere, the stiff-track mechanism is wrong and the live system is mislabelled. Columns: track_stiff_finish, track_sharpness, last_win_distance_yards, distance_yards, cp_down_trip_exp.",
        "observation_ids": [
          "O-7cdd45d9"
        ],
        "priority": 0.75
      },
      {
        "question": "Is the A/E 1.08 (and the sprint 1.51) carried by runners at 16/1 or longer, given BSP ROI +19% against SP ROI -14.5%?",
        "rationale": "Other threads found lifts that lived only in the 16/1+ band. If the lift holds up to 14/1, the system is credible. Columns: sp_decimal, sp_rank, race_type, distance_yards.",
        "observation_ids": [
          "O-7cdd45d9"
        ],
        "priority": 0.6
      },
      {
        "question": "Does the edge shrink as today's trip gets longer, as the hill-adds-stamina mechanism predicts?",
        "rationale": "A climb adds proportionally more stamina demand to a sprint than to a mile or more, so A/E should fall with distance. Columns: distance_yards, race_type, track_stiff_finish, track_straight_furlongs.",
        "observation_ids": [
          "O-7cdd45d9"
        ],
        "priority": 0.55
      }
    ],
    "hypotheses": [
      {
        "title": "Rival: dropping in trip after a win over further pays at any track, stiff or not",
        "family": "track-stamina",
        "operator": "rival-explanation",
        "question_id": null,
        "new_question": 0,
        "parent_id": "H181-proven-over-further-at-a-stiff-track",
        "reasoning": {
          "observation_ids": [
            "O-7cdd45d9"
          ],
          "question": "Is the stiff finish needed, or does the drop in trip alone carry the edge?",
          "mechanism": "Punters may mark down any horse dropping well below its winning trip as 'too slow', whatever the track. If so, the edge comes from the trip drop, not the hill.",
          "market_miss": "A drop in trip reads as a trip mismatch in the form book; the win over further is discounted as irrelevant to today.",
          "prediction": {
            "direction": "positive",
            "size": "A/E 1.05 to 1.08 on 15000+ bets at non-stiff tracks",
            "falsified_if": "A/E at or below 1.01 at non-stiff tracks, which would support the stiff-finish mechanism"
          },
          "rule_sketch": "track_stiff_finish = 0 AND last_win_distance_yards >= distance_yards + 330"
        },
        "confounders": [
          "sharp tracks favour speed and actively penalise stayers",
          "the mix of codes differs between stiff and non-stiff tracks",
          "field size"
        ],
        "expected_survival": 0.35
      },
      {
        "title": "Dose-response: the stiff-track edge is weaker at seven furlongs to a mile than in sprints",
        "family": "track-stamina",
        "operator": "test-mechanism",
        "question_id": null,
        "new_question": 2,
        "parent_id": "SYS-stayer-dropped-to-a-stiff-sprint",
        "reasoning": {
          "observation_ids": [
            "O-7cdd45d9"
          ],
          "question": "Does the edge shrink as today's trip gets longer, as the mechanism predicts?",
          "mechanism": "The uphill finish adds a roughly fixed stamina cost, which is a larger share of a sprint than of a mile, so stamina converts into speed most in short races.",
          "market_miss": "The market prices the trip drop the same way at every distance and does not scale it to how much the hill lengthens the race.",
          "prediction": {
            "direction": "positive",
            "size": "A/E 1.03 to 1.10 on 400+ bets, clearly below the sprint 1.51",
            "falsified_if": "A/E at or above the sprint segment's figure, or below 0.98"
          },
          "rule_sketch": "race_type = 'Flat' AND distance_yards > 1340 AND distance_yards <= 1760 AND track_stiff_finish = 1 AND last_win_distance_yards >= distance_yards + 330"
        },
        "confounders": [
          "horses dropping from a mile and a half or more are a different type of horse",
          "handicap mark",
          "the going"
        ],
        "expected_survival": 0.5
      },
      {
        "title": "Stiff sprint stayers on testing-ground tracks: more stamina demand should help more",
        "family": "track-stamina",
        "operator": "sharpen",
        "question_id": null,
        "new_question": null,
        "parent_id": "SYS-stayer-dropped-to-a-stiff-sprint",
        "reasoning": {
          "observation_ids": [
            "O-7cdd45d9"
          ],
          "question": "Is the sprint edge stronger where the track also tends to ride testing, adding to the stamina demand?",
          "mechanism": "A stiff finish on ground that rides testing compounds the stamina demand, so a sprint plays even more like a longer race.",
          "market_miss": "Sprint betting keys on early speed and last-time speed figures; the market does not credit stamina when the trip is short.",
          "prediction": {
            "direction": "positive",
            "size": "A/E 1.20 or more on 120+ bets",
            "falsified_if": "A/E below the parent sprint system's full-base figure on comparable bets"
          },
          "rule_sketch": "race_type = 'Flat' AND distance_yards <= 1340 AND track_stiff_finish = 1 AND track_testing_ground = 1 AND last_win_distance_yards >= distance_yards + 330"
        },
        "confounders": [
          "small number of courses, so course-specific effects",
          "season, since testing ground comes in autumn and spring",
          "price band"
        ],
        "expected_survival": 0.35
      }
    ],
    "findings": [
      {
        "statement": "The stiff-track trip-drop rule held across all three periods (A/E 1.06, 1.07, 1.12 on 9,279 bets), but BSP ROI of +19% against SP ROI of -14.5% means the price-band split must be checked before the edge is trusted.",
        "kind": "holds",
        "observation_ids": [
          "O-7cdd45d9"
        ]
      },
      {
        "statement": "The parent rule uses last_win_yards and the live system uses last_win_distance_yards; the two columns should be confirmed identical so the system really is a subset of its parent.",
        "kind": "method",
        "observation_ids": [
          "O-7cdd45d9"
        ]
      }
    ]
  }

Timeline

1. hypothesis note SYS-stayer-dropped-to-a-stiff-sprint

   15 Oct, 23:10 · importer

2. New idea SYS-stayer-dropped-to-a-stiff-sprint: System: Winner over further, sprinting at a stiff track (import)

   15 Oct, 23:10 · importer

Every change is an event with an actor: an agent and its version, an engine, a human, or the importer. Current stage: Live.