Breakneck Hill
816.0 m · net rise 64.4 m · total ascent 69.0 m · overall 7.9% · confidence: needs confirmation · East Stowford · Devon
Shape: sustained — 37% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 44 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.
needs review short_window_divergence — treat short-window maxima here as provisional.
Gradient ladder what do windows mean?
| Window | Maximum | Located at | |
|---|---|---|---|
| 2 m (diagnostic) | ≈56% | 58–60 m | under overhead cover terrain reads 66.1% at 49–51 m across a structure — excluded |
| 3 m (diagnostic) | ≈43% | 58–61 m | under overhead cover terrain reads 63.4% at 49–52 m across a structure — excluded |
| 5 m | ≈43% | 58–63 m | under overhead cover terrain reads 47.5% at 48–53 m across a structure — excluded |
| 10 m | ≈30% | 20–30 m | under overhead cover terrain reads 32.6% at 49–59 m across a structure — excluded |
| 20 m | ≈24.0% | 17–37 m | under overhead cover terrain reads 28.4% at 48–68 m across a structure — excluded |
| 25 m | ≈22.3% | 17–42 m | under overhead cover terrain reads 25.3% at 40–65 m across a structure — excluded |
| 50 m | ≈13.6% | 251–301 m | under overhead cover terrain reads 22.9% at 14–64 m across a structure — excluded |
| 100 m | ≈12.0% | 246–346 m | under overhead cover terrain reads 16.1% at 3–103 m across a structure — excluded |
may_start_earlier 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/england/bulk_dtm_1m/SS6025.tif"
],
"calculated_at": "2026-08-19T18:05:37+00:00",
"road_source": "OpenStreetMap (local PBF extract)",
"road_attribution": "\u00a9 OpenStreetMap contributors, ODbL",
"osm_pbf_path": "data/cache/pbf/england-2026-08-12.osm.pbf",
"osm_snapshot": "2026-08-12T20:21:46Z",
"elevation_provider": "Environment Agency",
"elevation_dataset": "EA LIDAR Composite DTM 1m (2022)",
"elevation_licence": "Open Government Licence v3 \u2014 \u00a9 Environment Agency",
"elevation_coverage_id": "13787b9a-26a4-4775-8523-806d13af58fc__Lidar_Composite_Elevation_DTM_1m",
"elevation_tile_ids": [
"SS6025.tif"
],
"route_summit_trim_m": 128.3,
"route_summit_trim_loss_m": 3.5,
"climb_origin": "discovered",
"notes": "Coarse pass: max 11.1% over 200 m (Terrain 50), gain 28.4 m over 262 m way. EXTENDED by graph walk: +0 segment(s) at base, +2 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting. ADOPTED (England launch slice 2026-08-16): clean-steep."
}