Lane near Llanarmon Mynydd Mawr
762.4 m · gain 84.5 m · overall 11.1% · Llanrhaeadr-ym-Mochnant · Powys
Shape: sustained — 43% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 132 m.
Documented on the ground — tag: 20% (2026). Signs get repainted and tags get retagged, so the date is part of the fact; on no cycling list we know of.
≈ Overhead cover (tree canopy or structures) spans 43% 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?
| Window | Maximum | Located at | |
|---|---|---|---|
| 2 m (diagnostic) | ≈42.5% | 334–336 m | under overhead cover |
| 3 m (diagnostic) | 39.9% | 130–133 m | |
| 5 m | 38.1% | 129–134 m | |
| 10 m | 33.8% | 124–134 m | |
| 20 m | ≈28.2% | 117–137 m | under overhead cover |
| 25 m | ≈26.8% | 112–137 m | under overhead cover |
| 50 m | ≈23.4% | 87–137 m | under overhead cover |
| 100 m | ≈20.5% | 111–211 m | under overhead cover |
may_start_earlier 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
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_313326_20200327dtm.tif",
"data/cache/wales/dtm_1m/wg_del_1_313327_20200327dtm.tif",
"data/cache/wales/dtm_1m/wg_del_1_314326_20200327dtm.tif",
"data/cache/wales/dtm_1m/wg_del_1_314327_20200327dtm.tif"
],
"calculated_at": "2026-08-12T09:12:10+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_1_313326_20200327dtm.tif",
"wg_del_1_313327_20200327dtm.tif",
"wg_del_1_314326_20200327dtm.tif",
"wg_del_1_314327_20200327dtm.tif"
],
"elevation_capture_dates": [
"27-03-2020"
],
"climb_origin": "osm_incline",
"signed_gradient_pct": 20.0,
"signed_source": "OSM incline tag 20% (editors=1, first tagged 2020-09-15)",
"notes": "Promoted automatically from triage verdict=validated. Named from nearest OSM place node (Llanarmon Mynydd Mawr); originally unnamed at (52.8322, -3.2843). EXTENDED by graph walk: +0 segment(s) at base, +1 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting."
}