Unnamed lane near Llanfihangel-y-Creuddyn
1171.0 m · net rise 113.7 m · total ascent 114.9 m · overall 9.7% · confidence: good
Shape: stepped — 47% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 151 m.
Found purely from mapping and LiDAR data, and not yet matched against books, race records or lists — it may be well known to locals under a name we've never heard. It was cross-checked against the OS road network, surface models and map tags, but 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 you know this road, tell us what you found — photographs, corrections and local knowledge all welcome; the map links below let you scout it first.
≈ Overhead cover (tree canopy or structures) spans 36% 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) | ≈46% | 438–440 m | under overhead cover |
| 3 m (diagnostic) | ≈40% | 437–440 m | under overhead cover |
| 5 m | ≈38% | 435–440 m | under overhead cover |
| 10 m | ≈33% | 430–440 m | under overhead cover |
| 20 m | ≈27.6% | 455–475 m | under overhead cover |
| 25 m | ≈27.1% | 451–476 m | under overhead cover |
| 50 m | ≈25.2% | 453–503 m | under overhead cover |
| 100 m | ≈22.9% | 403–503 m | under overhead cover |
Map
Check this route yourself: Google Maps route via their router · Street View at the base where coverage exists · OSM way 27087050 highlights the mapped road · 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_22_266274_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_266275_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_267274_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_267275_20220114dtm.tif"
],
"calculated_at": "2026-08-13T02:09:00+00:00",
"road_source": "OpenStreetMap",
"road_attribution": "\u00a9 OpenStreetMap contributors, ODbL",
"osm_ids": [
27087050
],
"osm_versions": {
"27087050": 4
},
"osm_timestamps": {
"27087050": "2024-02-13T11:55:44Z"
},
"osm_retrieved_at": "2026-08-13T02:08:57+00:00",
"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_266274_20220114dtm.tif",
"wg_del_22_266275_20220114dtm.tif",
"wg_del_22_267274_20220114dtm.tif",
"wg_del_22_267275_20220114dtm.tif"
],
"elevation_capture_dates": [
"14-01-2022"
],
"route_summit_trim_m": 223.3,
"route_summit_trim_loss_m": 24.4,
"climb_origin": "discovered",
"notes": "Top of Rheidol sweep by max 100 m (22.9%); no incline tag, on no list."
}