BETA — measurements and names under active refinement. Seen a sign, a gate, or a better name? Report it (photos welcome).
Llangynog to Cwm Pydew°
7377.4 m · gain 304.2 m · overall 4.1% · Cwm Rhiweirth · Powys
Shape: sustained — 35% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 207 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 (52.8510, -3.4350)'). Corrections welcome.
Gradient ladder what do windows mean?
| Window | Maximum | Located at | |
|---|---|---|---|
| 2 m (diagnostic) | ≈32.2% | 4201–4203 m | under overhead cover terrain reads 40.1% at 4302–4304 m across a structure — excluded |
| 3 m (diagnostic) | ≈25.4% | 4200–4203 m | under overhead cover terrain reads 47.1% at 4303–4306 m across a structure — excluded |
| 5 m | ≈18.7% | 4198–4203 m | under overhead cover terrain reads 29.6% at 4302–4307 m across a structure — excluded |
| 10 m | ≈12.9% | 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
© 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": [
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],
"calculated_at": "2026-08-12T09:09:12+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",
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"elevation_capture_dates": [
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],
"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)'.",
"naming_note": "auto-named from gazetteer (hypothesis, unreviewed); discovered as 'Discovered lane (52.8510, -3.4350)'"
}