Lane near Tom's Rock
476.0 m · net rise 32.1 m · total ascent 35.2 m · overall 6.7% · evidence quality U (needs confirmation) · Tom's Rock · Cornwall · share
Shape: stepped — 59% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 139 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) | ≈38% | 412–414 m | under overhead cover terrain reads 50.2% at 406–408 m across a structure — excluded |
| 3 m (diagnostic) | ≈37% | 413–416 m | under overhead cover terrain reads 42.6% at 406–409 m across a structure — excluded |
| 5 m | ≈34% | 411–416 m | under overhead cover terrain reads 38.3% at 403–408 m across a structure — excluded |
| 10 m | ≈19% | 357–367 m | under overhead cover terrain reads 33.6% at 406–416 m across a structure — excluded |
| 20 m | ≈17.9% | 352–372 m | under overhead cover terrain reads 28.5% at 397–417 m across a structure — excluded |
| 25 m | ≈17.7% | 356–381 m | under overhead cover terrain reads 25.6% at 392–417 m across a structure — excluded |
| 50 m | ≈16.7% | 350–400 m | under overhead cover terrain reads 21.2% at 367–417 m across a structure — excluded |
| 100 m | ≈15.2% | 300–400 m | under overhead cover terrain reads 18.5% at 317–417 m across a structure — excluded |
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
No aerial layer here: Britain has no open or government source of aerial photography at road scale — the pan-government APGB imagery is licensed to the public sector only, unlike the LiDAR this survey is measured from. Street View, where it exists, is the visual check.
This climb's data: OCL JSON — the full gradient ladder, quality flags and provenance in the OpenClimb Ladder format.
Access: Listed 2026-09-15 (re-measured on the trimmed extent): with the route cut back to the crest and the current masks applied, the steepest 25 m reads 17.7 % (it was published at 25.6 %), below the ranking door — kept as a listed page with the re-measured profile.
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
Route colour = gradient over a 25 m window: <10% 10–20% 20–25% ≥25%
© OpenStreetMap contributors · topo tiles © OpenTopoMap (CC-BY-SA) · vector tiles OpenFreeMap
Profile
The map, 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. Any 25 m figure is good to about a point either way (why).
Measurement card
| Elevation | Environment Agency — EA LIDAR Composite DTM 1m (2022) |
|---|---|
| Resolution / CRS | 1.0 m grid, EPSG:27700; sampled every 1.0 m, bilinear interpolation |
| Tiles | E184000_N38000_2000m.tif, E184000_N40000_2000m.tif |
| Road centreline | OpenStreetMap (local PBF extract), snapshot 2026-08-26T20:22:15Z |
| Quality status | evidence quality U; review flags: short window divergence |
| Analysis | OCL 0.1.0, analysis 0.1.0, run retro-260914, calculated 2026-09-15 |
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/dtm_1m/E184000_N38000_2000m.tif",
"data/cache/england/dtm_1m/E184000_N40000_2000m.tif"
],
"calculated_at": "2026-09-15T02:54:01+00:00",
"road_source": "OpenStreetMap (local PBF extract)",
"road_attribution": "\u00a9 OpenStreetMap contributors, ODbL",
"osm_pbf_path": "data/cache/pbf/england-2026-08-27.osm.pbf",
"osm_snapshot": "2026-08-26T20:22:15Z",
"run_id": "retro-260914",
"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": [
"E184000_N38000_2000m.tif",
"E184000_N40000_2000m.tif"
],
"route_cut_m": 476.0,
"climb_origin": "discovered",
"structure_own_ways": "none \u2014 the route carried no way list; own decks unmasked",
"mask_ranges_m": [
[
1097.0,
1141.0
]
],
"license": "ODbL-1.0",
"license_url": "https://howsteep.org/licensing"
}