Bwlch Sychnant
743.4 m · net rise 92.9 m · total ascent 95.5 m · overall 12.5% · confidence: good · Capelulo · Conwy
Shape: sustained — 27% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 339 m.
Matches: Wikipedia, Simon Warren 100 Climbs app (Wales collections) — Sychnant Pass — articles in English and Welsh; route-line 2 m from the pass point — Sychnant Pass — listed unnumbered; attribution to confirm in-app.
≈ Overhead cover (tree canopy or structures) spans 14% 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) | ≈41% | 510–512 m | under overhead cover terrain reads 76.3% at 8–10 m across a structure — excluded |
| 3 m (diagnostic) | ≈25% | 510–513 m | under overhead cover terrain reads 74.6% at 7–10 m across a structure — excluded |
| 5 m | ≈21% | 510–515 m | under overhead cover terrain reads 60.4% at 6–11 m across a structure — excluded |
| 10 m | ≈17% | 510–520 m | under overhead cover terrain reads 41.0% at 14–24 m across a structure — excluded |
| 20 m | ≈15.2% | 563–583 m | under overhead cover terrain reads 35.8% at 6–26 m across a structure — excluded |
| 25 m | ≈15.0% | 559–584 m | under overhead cover terrain reads 30.0% at 6–31 m across a structure — excluded |
| 50 m | ≈14.6% | 537–587 m | under overhead cover terrain reads 19.3% at 6–56 m across a structure — excluded |
| 100 m | ≈13.9% | 510–610 m | under overhead cover terrain reads 14.3% at 6–106 m across a structure — excluded |
may_start_earliermay_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_19_274376_20211221dtm.tif",
"data/cache/wales/dtm_1m/wg_del_19_275376_20211221dtm.tif",
"data/cache/wales/dtm_1m/wg_del_19_275377_20211221dtm.tif",
"data/cache/wales/dtm_1m/wg_del_27_274377_20220305dtm.tif"
],
"calculated_at": "2026-08-12T00:57:45+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_19_274376_20211221dtm.tif",
"wg_del_19_275376_20211221dtm.tif",
"wg_del_19_275377_20211221dtm.tif",
"wg_del_27_274377_20220305dtm.tif"
],
"elevation_capture_dates": [
"05-03-2022",
"22-12-2021"
],
"climb_origin": "discovered",
"notes": "Coarse pass: max 15.8% over 200 m (Terrain 50), gain 68.9 m over 502 m way. EXTENDED by graph walk: +2 segment(s) at base, +1 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting. DEDUPE: absorbed 1 overlapping proposal(s): conwy-old-road"
}