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Discovered lane (44.9828, 4.6413)

454.3 m · net rise 38.0 m · total ascent 41.6 m · overall 8.4% · evidence quality B (good) · Saint-Barthélemy-Grozon · Ardèche · share

Shape: sustained — 40% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 59 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 IGN’s BD TOPO® road network, OpenStreetMap and the classified LiDAR HD point cloud, 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.

≈ Overhead cover (tree canopy or structures) spans 80% 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?

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.

Surface: mixed (72% unpaved), according to BD TOPO®, IGN's national topographic database: unpaved for the first 326 m; paved from 326 m to the top. The steepest 25 m lies on the unpaved part.

Access: Listed 2026-09-22 (inventory hunt wave 1): road audit — way 582530964: unnamed service way; way 582530964: service way, surface untagged. Never silently ranked or dropped (Peter, 2026-08-27).

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

Load the interactive map

Route colour = gradient over a 25 m window: <10% 10–20% 20–25% ≥25%

Topo (contours) Vector Aerial   © OpenStreetMap contributors · topo tiles © OpenTopoMap (CC-BY-SA) · vector tiles OpenFreeMap · aerial imagery © IGN, BD ORTHO® (Licence Ouverte Etalab 2.0)

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

Provenance

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  "sample_interval_m": 1.0,
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  "calculated_at": "2026-09-22T14:22:14+00:00",
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  "climb_origin": "discovered",
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