Bwlch Penbarras
2323.9 m · net rise 259.8 m · total ascent 266.5 m · overall 11.2% · confidence: needs confirmation · Llanbedr-Dyffryn-Clwyd · Sir Ddinbych / Denbighshire
Shape: sustained — 34% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 481 m.
Matches: 100 Greatest Cycling Climbs (Simon Warren), British National Hill Climb Championship, Wikipedia — The Moel Famau / Shrine road climb — Venue 2001 (as "Y Bwlch, Ruthin" — the pass's local name; winner Jim Henderson) — Has its own article (mountain pass, Clwydian Range) — No. 88, as "Penbarra" (official app, 2026 numbering).
needs review short_window_divergence — treat short-window maxima here as provisional.
≈ Overhead cover (tree canopy or structures) spans 30% 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) | ≈54% | 462–464 m | under overhead cover |
| 3 m (diagnostic) | ≈40% | 461–464 m | under overhead cover terrain reads 40.5% at 232–235 m across a structure — excluded |
| 5 m | ≈37% | 461–466 m | under overhead cover |
| 10 m | ≈28% | 688–698 m | under overhead cover terrain reads 29.9% at 436–446 m across terrain that holds no road surface (dense canopy, no bench) — excluded |
| 20 m | ≈24.6% | 678–698 m | under overhead cover |
| 25 m | ≈24.4% | 671–696 m | under overhead cover |
| 50 m | 21.9% | 1070–1120 m | |
| 100 m | 20.6% | 1028–1128 m |
may_continue_beyond_end 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
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_7_314359_20210211dtm.tif",
"data/cache/wales/dtm_1m/wg_del_7_314360_20210211dtm.tif",
"data/cache/wales/dtm_1m/wg_del_7_315359_20210211dtm.tif",
"data/cache/wales/dtm_1m/wg_del_7_315360_20210211dtm.tif",
"data/cache/wales/dtm_1m/wg_del_7_316359_20210211dtm.tif",
"data/cache/wales/dtm_1m/wg_del_7_316360_20210211dtm.tif"
],
"calculated_at": "2026-08-12T09:06:18+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_7_314359_20210211dtm.tif",
"wg_del_7_314360_20210211dtm.tif",
"wg_del_7_315359_20210211dtm.tif",
"wg_del_7_315360_20210211dtm.tif",
"wg_del_7_316359_20210211dtm.tif",
"wg_del_7_316360_20210211dtm.tif"
],
"elevation_capture_dates": [
"11-02-2021"
],
"climb_origin": "discovered",
"notes": "Coarse pass: max 18.9% over 200 m (Terrain 50), gain 215.1 m over 1850 m way. EXTENDED by graph walk: +3 segment(s) at base, +0 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting. DEDUPE: absorbed 1 overlapping proposal(s): l-n-cae-glas ADOPTED (notable slice 2026-08-11): endurance."
}