Aberarth to Graig Ddu
1967.0 m · net rise 98.1 m · total ascent 99.7 m · overall 5.0% · confidence: high
Shape: sustained — 32% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 96 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.
Gradient ladder what do windows mean?
| Window | Maximum | Located at | |
|---|---|---|---|
| 2 m (diagnostic) | 20% | 1328–1330 m | |
| 3 m (diagnostic) | 14% | 194–197 m | |
| 5 m | 14% | 192–197 m | |
| 10 m | 13% | 189–199 m | |
| 20 m | 12.9% | 182–202 m | |
| 25 m | 12.9% | 189–214 m | |
| 50 m | 12.7% | 177–227 m | |
| 100 m | 11.8% | 146–246 m |
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_23_250263_20220117dtm.tif",
"data/cache/wales/dtm_1m/wg_del_23_250264_20220117dtm.tif",
"data/cache/wales/dtm_1m/wg_del_24_249263_20220120dtm.tif",
"data/cache/wales/dtm_1m/wg_del_27_247263_20220305dtm.tif",
"data/cache/wales/dtm_1m/wg_del_27_247264_20220305dtm.tif",
"data/cache/wales/dtm_1m/wg_del_27_248263_20220305dtm.tif",
"data/cache/wales/dtm_1m/wg_del_27_248264_20220305dtm.tif",
"data/cache/wales/dtm_1m/wg_del_27_248265_20220305dtm.tif",
"data/cache/wales/dtm_1m/wg_del_27_249264_20220305dtm.tif",
"data/cache/wales/dtm_1m/wg_del_27_249265_20220305dtm.tif",
"data/cache/wales/dtm_1m/wg_del_27_250265_20220305dtm.tif"
],
"calculated_at": "2026-08-13T02:13:55+00:00",
"road_source": "trunk-adopted-routes/discovered-lane-52-2615-4-2065.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": [
"wg_del_23_250263_20220117dtm.tif",
"wg_del_23_250264_20220117dtm.tif",
"wg_del_24_249263_20220120dtm.tif",
"wg_del_27_247263_20220305dtm.tif",
"wg_del_27_247264_20220305dtm.tif",
"wg_del_27_248263_20220305dtm.tif",
"wg_del_27_248264_20220305dtm.tif",
"wg_del_27_248265_20220305dtm.tif",
"wg_del_27_249264_20220305dtm.tif",
"wg_del_27_249265_20220305dtm.tif",
"wg_del_27_250265_20220305dtm.tif"
],
"elevation_capture_dates": [
"05-03-2022",
"17-01-2022"
],
"route_summit_trim_m": 821.6,
"route_summit_trim_loss_m": 17.2,
"climb_origin": "discovered",
"notes": "Coarse pass: max 7.0% over 200 m (Terrain 50), gain 46.3 m over 2196 m way. EXTENDED by graph walk: +4 segment(s) at base, +0 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting. ADOPTED (trunk sweep, Peter's on-sight verdict 2026-08-12): clean table, adopt-all. AUTO-NAMED from gazetteer (hypothesis, unreviewed): was 'Discovered lane (52.2615, -4.2065)'."
}