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Milltir Gerrig
5940.0 m · net rise 324.9 m · total ascent 337.2 m · overall 5.5% · confidence: good
Shape: sustained — 31% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 207 m.
Matches: Wikipedia — Milltir Gerrig (Milltir Cerrig) — articles in English and Welsh; route passes 11 m from the pass point.
≈ Overhead cover (tree canopy or structures) spans 6% of this route — detected by comparing the surface model (DSM, treetops and rooftops) against the terrain model (DTM, bare ground). Under cover the bare-ground model is built from fewer laser returns, so metre-scale readings can wobble; maxima whose window sits in a covered zone are marked ≈ below — less certain — the flag does not say whether the true value is higher or lower. Longer windows average over more clean ground and are steadier.
Gradient ladder what do windows mean?
| Window | Maximum | Located at | |
|---|---|---|---|
| 2 m (diagnostic) | ≈32% | 4201–4203 m | under overhead cover terrain reads 40.1% at 4302–4304 m across a structure — excluded |
| 3 m (diagnostic) | ≈25% | 4200–4203 m | under overhead cover terrain reads 47.1% at 4303–4306 m across a structure — excluded |
| 5 m | ≈19% | 4198–4203 m | under overhead cover terrain reads 29.6% at 4302–4307 m across a structure — excluded |
| 10 m | ≈13% | 4193–4203 m | under overhead cover terrain reads 21.0% at 4296–4306 m across a structure — excluded |
| 20 m | ≈11.5% | 374–394 m | under overhead cover terrain reads 13.2% at 4286–4306 m across a structure — excluded |
| 25 m | ≈11.3% | 313–338 m | under overhead cover terrain reads 11.6% at 4281–4306 m across a structure — excluded |
| 50 m | 11.1% | 98–148 m | |
| 100 m | ≈11.1% | 96–196 m | under overhead cover |
Map
Check this route yourself: Google Maps route via their router · Street View at the base where coverage exists · geojson.io our exact measured line · OpenTopoMap
This climb's data: OCL JSON — the full gradient ladder, quality flags and provenance in the OpenClimb Ladder format.
Ridden it, or know better? Submit data for this climb no account needed
© OpenStreetMap contributors · topo tiles © OpenTopoMap (CC-BY-SA) · vector tiles OpenFreeMap
Profile
Provenance
{
"analysis_version": "0.1.0",
"sample_interval_m": 1.0,
"interpolation": "bilinear",
"smoothing": "none",
"gradient_windows_m": [
5.0,
10.0,
20.0,
25.0,
50.0,
100.0
],
"diagnostic_windows_m": [
2.0,
3.0
],
"elevation_crs": "EPSG:27700",
"elevation_resolution_m": 1.0,
"elevation_tiles": [
"data/cache/wales/dtm_1m/wg_del_1_300326_20200327dtm.tif",
"data/cache/wales/dtm_1m/wg_del_1_300327_20200327dtm.tif",
"data/cache/wales/dtm_1m/wg_del_1_300328_20200327dtm.tif",
"data/cache/wales/dtm_1m/wg_del_1_300329_20200327dtm.tif",
"data/cache/wales/dtm_1m/wg_del_1_300330_20200327dtm.tif",
"data/cache/wales/dtm_1m/wg_del_1_300331_20200327dtm.tif",
"data/cache/wales/dtm_1m/wg_del_1_301326_20200327dtm.tif",
"data/cache/wales/dtm_1m/wg_del_1_301327_20200327dtm.tif",
"data/cache/wales/dtm_1m/wg_del_1_301328_20200327dtm.tif",
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"data/cache/wales/dtm_1m/wg_del_1_301330_20200327dtm.tif",
"data/cache/wales/dtm_1m/wg_del_1_301331_20200327dtm.tif",
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"data/cache/wales/dtm_1m/wg_del_1_302330_20200327dtm.tif",
"data/cache/wales/dtm_1m/wg_del_1_302331_20200327dtm.tif",
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"data/cache/wales/dtm_1m/wg_del_1_303330_20200327dtm.tif",
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"data/cache/wales/dtm_1m/wg_del_1_304328_20200327dtm.tif",
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],
"calculated_at": "2026-08-13T02:12:03+00:00",
"road_source": "wales-discovered-adopted-routes/discovered-lane-52-8510-3-4350.geojson",
"elevation_provider": "Welsh Government",
"elevation_dataset": "Welsh Government LiDAR 1m DTM (2020-2023)",
"elevation_licence": "Open Government Licence v3 \u2014 \u00a9 Crown copyright Welsh Government",
"elevation_catalogue_layer": "geonode:welsh_government_lidar_tile_catalogue_2020_2023",
"elevation_tile_ids": [
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],
"elevation_capture_dates": [
"27-03-2020"
],
"route_summit_trim_m": 1437.4,
"route_summit_trim_loss_m": 20.7,
"climb_origin": "discovered",
"notes": "Coarse pass: max 11.6% over 200 m (Terrain 50), gain 295.2 m over 7234 m way. EXTENDED by graph walk: +1 segment(s) at base, +0 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting. DEDUPE: absorbed 1 overlapping proposal(s): discovered-lane-52-8483-3-4321 ADOPTED (notable slice 2026-08-11): big-gain. AUTO-NAMED from gazetteer (hypothesis, unreviewed): was 'Discovered lane (52.8510, -3.4350)'.",
"renamed": "2026-08-13: 'Milltir Gerrig' adopted over auto-name 'Llangynog to Cwm Pydew' \u2014 identification-certain (11 m from Wikidata pass point; en+cy Wikipedia); standing policy per Peter"
}