Brynllys to Bwlch Oerddrws°
5158.9 m · gain 247.6 m · overall 4.8% · Cwm Cerist · Gwynedd
Shape: stepped — 52% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 362 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 (52.7328, -3.7339)'). Corrections welcome.
Gradient ladder what do windows mean?
| Window | Maximum | Located at | |
|---|---|---|---|
| 2 m (diagnostic) | 23.8% | 2536–2538 m | |
| 3 m (diagnostic) | 22.8% | 2536–2539 m | |
| 5 m | 20.1% | 2535–2540 m | |
| 10 m | 17.7% | 4822–4832 m | |
| 20 m | 16.8% | 4819–4839 m | |
| 25 m | 16.5% | 4817–4842 m | |
| 50 m | 15.1% | 4806–4856 m | |
| 100 m | 14.9% | 3506–3606 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.
© 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_280315_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_280316_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_280317_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_281315_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_281316_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_281317_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_282315_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_282316_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_282317_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_283315_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_283316_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_283317_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_284315_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_284316_20220114dtm.tif",
"data/cache/wales/dtm_1m/wg_del_22_284317_20220114dtm.tif"
],
"calculated_at": "2026-08-12T23:11:59+00:00",
"road_source": "trunk-adopted-routes/discovered-lane-52-7328-3-7339.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_22_280315_20220114dtm.tif",
"wg_del_22_280316_20220114dtm.tif",
"wg_del_22_280317_20220114dtm.tif",
"wg_del_22_281315_20220114dtm.tif",
"wg_del_22_281316_20220114dtm.tif",
"wg_del_22_281317_20220114dtm.tif",
"wg_del_22_282315_20220114dtm.tif",
"wg_del_22_282316_20220114dtm.tif",
"wg_del_22_282317_20220114dtm.tif",
"wg_del_22_283315_20220114dtm.tif",
"wg_del_22_283316_20220114dtm.tif",
"wg_del_22_283317_20220114dtm.tif",
"wg_del_22_284315_20220114dtm.tif",
"wg_del_22_284316_20220114dtm.tif",
"wg_del_22_284317_20220114dtm.tif"
],
"elevation_capture_dates": [
"14-01-2022"
],
"climb_origin": "discovered",
"notes": "Coarse pass: max 8.0% over 200 m (Terrain 50), gain 78.7 m over 3266 m way. 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. ADOPTED (trunk sweep, Peter's on-sight verdict 2026-08-12): clean table, adopt-all. AUTO-NAMED from gazetteer (hypothesis, unreviewed): was 'Discovered lane (52.7328, -3.7339)'.",
"naming_note": "auto-named from gazetteer (hypothesis, unreviewed); discovered as 'Discovered lane (52.7328, -3.7339)'"
}