Brynllys to Bwlch Oerddrws
5158.9 m · net rise 247.6 m · total ascent 260.6 m · overall 4.8% · confidence: good · Cwm yr Eglwys · Gwynedd · share
Shape: stepped — 52% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 362 m.
Matches: Wikipedia — Bwlch yr Oerddrws — Welsh Wikipedia article on the pass; this is the eastern ascent.
Gradient ladder what do windows mean?
| Window | Maximum | Located at | |
|---|---|---|---|
| 2 m (diagnostic) | ≈19% | 4724–4726 m | under overhead cover terrain reads 23.8% at 2536–2538 m across a structure — excluded |
| 3 m (diagnostic) | ≈18% | 4827–4830 m | under overhead cover terrain reads 22.8% at 2536–2539 m across a structure — excluded |
| 5 m | ≈18% | 4826–4831 m | under overhead cover terrain reads 20.1% at 2535–2540 m across a structure — excluded |
| 10 m | 18% | 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.
Measured, not vetted. This page records what the laser record shows about the road's shape — nothing more. Nobody has necessarily ridden or inspected this road for the survey, and a page here is not a recommendation and no guarantee that the road is open, surfaced, rideable or safe. Gates, private sections, missing rights of way and hazards do not show up in elevation data. Check access and conditions on the ground and make your own judgment.
Ridden it, or know better? Submit data for this climb no account needed · Share this climb
© OpenStreetMap contributors · topo tiles © OpenTopoMap (CC-BY-SA) · vector tiles OpenFreeMap
Profile
The profile and gradient chart share one position — move your pointer over them and the marker follows. Colors are the gradient bands; the shaded span is the steepest 25 m.
Measurement card
| Elevation | Welsh Government — Welsh Government LiDAR 1m DTM (2020-2023) |
|---|---|
| Resolution / CRS | 1.0 m grid, EPSG:27700; sampled every 1.0 m, bilinear interpolation |
| Tiles | 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 |
| Road centreline | OpenStreetMap (local PBF extract), snapshot 2026-08-10T20:21:40Z |
| Quality status | measurement confidence B; caveated windows: structure excluded |
| Analysis | OCL 0.1.0, analysis 0.1.0, run mask-rebatch-mini-wales-260823, calculated 2026-08-23 |
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": "2026-08-23T15:00:32+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",
"run_id": "mask-rebatch-mini-wales-260823",
"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",
"mask_ranges_m": [
[
2529.0,
2557.0
]
],
"license": "ODbL-1.0",
"license_url": "https://howsteep.org/licensing.html"
}