How to Read a Topographic Map for Cycling (Contour Lines Explained)
Contour lines show you where the climbs are, how steep they get and where the road will go. Here's how to read them and work out a climb's gradient before you ride.
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Five minutes with contour lines and you'll never be surprised by a climb again.
Route apps show an elevation profile, but a topographic map shows you the shape of the whole landscape: where the hills are, how steep they get and which way the road will have to wind to get up them. Here's how to read one as a cyclist.
What contour lines are
A contour line joins points of equal height. Walk along one and you'd stay perfectly level. Each line is a fixed height above the next one down, called the contour interval. The interval is printed in the map's legend; it's often 10 or 20 meters, but it varies from map to map, so always check.
Most maps also draw every fifth line slightly thicker and label it with its height. These are index contours, and they make counting much faster.
Spacing tells you steepness
- Lines close together: steep ground. On a road, expect a hard climb or switchbacks.
- Lines far apart: gentle ground. Good for recovery or a fast tempo.
- Evenly spaced lines: a steady slope, the kind you can pace well.
- Lines that bunch up partway: the gradient kicks up. Save something for that section.
Spot summits, valleys and passes
- Small closed rings are summits (or, if marked with tick marks, hollows).
- V-shapes pointing uphill are valleys, usually with a stream in the bottom. Roads often follow them because they're the easiest way up.
- V-shapes pointing downhill are ridges or spurs.
- An hourglass shape between two summits is a saddle, or pass. That's where a road crossing the range will go.
Work out the gradient of a climb
Gradient is the height gained divided by the distance traveled, times 100.
- Count the contour lines the road crosses on the climb and multiply by the contour interval. That's the height gained.
- Measure the road distance between the bottom and the top using the map's scale (follow the bends, not a straight line).
- Divide height by distance and multiply by 100.
Example: the road crosses 15 lines at a 20 m interval, so it climbs 300 m. It does that over 4 km of road (4,000 m). 300 ÷ 4,000 × 100 = 7.5%. That's a proper climb, and worth pacing carefully: see how to pace a long climb.
Use it to plan your ride
- Find the climbs you want: look for roads crossing many lines in a short distance.
- Find the climbs you don't: on a recovery day, pick roads that follow the lines instead of crossing them.
- Read the descent too: tight switchbacks where lines are close together mean braking early.
- Check your gearing: if the map shows long sections above 8–10%, read what gearing you need for hills before you go.
Want a number before you ride? Our cycling calculators estimate climb times from distance, gradient and your power.
Wear the map
Our Contour jersey ($99.95) is drawn exactly this way: dusty lilac contour lines on deep olive, heavier every fifth line, with tight summits and open valleys and one citron line through the terrain. The landscape is imagined, so it's no particular place. If you want a real climb you've ridden on a jersey instead, Your Ride prints your own route and elevation profile.
Get yours
Every Corbah jersey is made to order (about 5–6 weeks) with free personalization. See more mountain designs in Climbs, and check the size guide first: we don't take returns or exchanges, but if the size is wrong you keep the jersey and can order another size within 15 days of delivery for about 20–60% off.
