BETA — measurements and names under active refinement. Seen a sign, a gate, or a better name? Report it (photos welcome).

← all climbs

Cwm y Gâth to Bryn-y-Fedwen°

9334.3 m · gain 423.4 m · overall 4.5% · Banc y Cwm · Powys

Shape: sustained — 42% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 329 m.

An unlisted find of this survey, on no list we know of. It was discovered by analysing LiDAR terrain data and cross-checked against the OS road network, surface models and map tags — but despite all that, a discovery can still be an artifact of the terrain model or the map. Treat it as a well-evidenced hypothesis until someone has ridden it. If that someone is you, tell us what you found — photographs, corrections and local knowledge all welcome; the map links below let you scout it first.

° The name is provisional: this climb appears on no list we know of, so it was named from nearby map places. There is no evidence of local usage — (auto-named from gazetteer (hypothesis, unreviewed); discovered as 'Discovered lane (52.5600, -3.7176)'). Corrections welcome.

needs review short_window_divergence — treat short-window maxima here as provisional.

≈ Overhead cover (tree canopy or structures) spans 15% 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, not wrong. Longer windows average over more clean ground and are steadier.

Gradient ladder what do windows mean?

WindowMaximumLocated at
2 m (diagnostic)≈46.3%2109–2111 munder overhead cover terrain reads 94.6% at 9–11 m across a structure — excluded
3 m (diagnostic)≈43.4%2108–2111 munder overhead cover terrain reads 85.0% at 9–12 m across a structure — excluded
5 m≈37.5%2107–2112 munder overhead cover terrain reads 60.5% at 9–14 m across a structure — excluded
10 m≈29.4%6357–6367 munder overhead cover terrain reads 31.2% at 9–19 m across a structure — excluded
20 m25.0%6347–6367 m
25 m22.6%6342–6367 m
50 m19.8%6347–6397 m
100 m16.9%7497–7597 m

may_start_earlierdescends_at_end Extent detection suggests reviewing where this climb starts/ends.

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

  © OpenStreetMap contributors · topo tiles © OpenTopoMap (CC-BY-SA) · vector tiles OpenFreeMap

Cwm y Gâth to Bryn-y-Fedwen LiDAR hillshade map with contours

Profile

Cwm y Gâth to Bryn-y-Fedwen elevation profile Cwm y Gâth to Bryn-y-Fedwen rolling gradient 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_22_278294_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_278295_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_278296_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_278297_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_278298_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_279294_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_279295_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_279296_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_279297_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_279298_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_280294_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_280295_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_280296_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_280297_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_280298_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_281294_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_281295_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_281296_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_281297_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_281298_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_282294_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_282295_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_282296_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_282297_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_282298_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_283294_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_283295_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_283296_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_283297_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_283298_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_284294_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_284295_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_284296_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_284297_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_284298_20220314dtm.tif"
  ],
  "calculated_at": "2026-08-12T09:08:42+00:00",
  "road_source": "OpenStreetMap (local PBF extract)",
  "road_attribution": "\u00a9 OpenStreetMap contributors, ODbL",
  "osm_pbf_path": "data/cache/pbf/wales-2026-08-11.osm.pbf",
  "osm_snapshot": "2026-08-10T20:21:40Z",
  "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": [
    "wg_del_22_278294_20220114dtm.tif",
    "wg_del_22_278295_20220114dtm.tif",
    "wg_del_22_278296_20220114dtm.tif",
    "wg_del_22_278297_20220114dtm.tif",
    "wg_del_22_278298_20220114dtm.tif",
    "wg_del_22_279294_20220114dtm.tif",
    "wg_del_22_279295_20220114dtm.tif",
    "wg_del_22_279296_20220114dtm.tif",
    "wg_del_22_279297_20220114dtm.tif",
    "wg_del_22_279298_20220114dtm.tif",
    "wg_del_22_280294_20220114dtm.tif",
    "wg_del_22_280295_20220114dtm.tif",
    "wg_del_22_280296_20220114dtm.tif",
    "wg_del_22_280297_20220114dtm.tif",
    "wg_del_22_280298_20220114dtm.tif",
    "wg_del_22_281294_20220114dtm.tif",
    "wg_del_22_281295_20220114dtm.tif",
    "wg_del_22_281296_20220114dtm.tif",
    "wg_del_22_281297_20220114dtm.tif",
    "wg_del_22_281298_20220114dtm.tif",
    "wg_del_22_282294_20220114dtm.tif",
    "wg_del_22_282295_20220114dtm.tif",
    "wg_del_22_282296_20220114dtm.tif",
    "wg_del_22_282297_20220114dtm.tif",
    "wg_del_22_282298_20220114dtm.tif",
    "wg_del_28_283294_20220314dtm.tif",
    "wg_del_28_283295_20220314dtm.tif",
    "wg_del_28_283296_20220314dtm.tif",
    "wg_del_28_283297_20220314dtm.tif",
    "wg_del_28_283298_20220314dtm.tif",
    "wg_del_28_284294_20220314dtm.tif",
    "wg_del_28_284295_20220314dtm.tif",
    "wg_del_28_284296_20220314dtm.tif",
    "wg_del_28_284297_20220314dtm.tif",
    "wg_del_28_284298_20220314dtm.tif"
  ],
  "elevation_capture_dates": [
    "14-01-2022",
    "14-03-2022"
  ],
  "climb_origin": "discovered",
  "notes": "Coarse pass: max 15.7% over 200 m (Terrain 50), gain 413.8 m over 9250 m way. EXTENDED by graph walk: +2 segment(s) at base, +0 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting. ADOPTED (notable slice 2026-08-11): big-gain. AUTO-NAMED from gazetteer (hypothesis, unreviewed): was 'Discovered lane (52.5600, -3.7176)'.",
  "naming_note": "auto-named from gazetteer (hypothesis, unreviewed); discovered as 'Discovered lane (52.5600, -3.7176)'"
}