Slack hill: Cycling Climb

The climb

About Slack hill

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Simon Warren’s Another 100 Greatest Cycling Climbs

Slack Hill presents a direct climb on the A632 between Chesterfield and Matlock. This approach heads south-west, with about 1.3 kilometres of rising road ahead. Its largely straight line gives you a clear impression of the slope, and the lower part supplies the hardest work. There are few turns to divide the ascent into convenient stages, so the road's visible rise becomes a more useful guide than any promise of a hidden easing around the next corner.

As you gain height, the gradient gradually relents. The contrast with the opening makes the upper section feel more manageable, even though the climb is not yet over. At an average of around 8.5 per cent, the whole ascent remains substantial for its relatively modest length. Slack Hill's appeal lies in that uncomplicated shape: a strong initial demand, a gradual release and a clear sense of the height gained.

01 / The ascent

Elevation profile

Start 183 m · Summit 298 m

Gradient by distance1.35 km / 115 m gain

0 km0.3 km0.5 km0.8 km1.1 km1.3 km

02 / The numbers

Climb statistics

Distance: 1.35 km
Elevation gain: 115 m
Average gradient: 8.5%
Climb category: 4
Start elevation: 183 m
Summit elevation: 298 m

Current weather

At the climb start

Loading weather…

Weather data: MET Norway

03 / Your effort

How long would it take?

Enter the power you could hold for the whole climb. We calculate a moving time from the elevation profile and the forces you ride against.

Sustained power

W/kg

Use your intended climbing effort, rather than FTP unless you can hold it for the predicted duration.

Rider weight (kg)

Bike + kit weight (kg)

Bike + kit includes clothing, bottles and luggage.

Advanced settings

Defaults represent a road-bike scenario. Adjust these settings to match your tyres, drivetrain and riding position.

Effective drag area (CdA) (m²)

Rolling resistance (Crr)

Drivetrain efficiency (%)

Modelled moving time

8 min

Power throughout: 225 W
Average speed: 10.3 km/h

Based on the 1.35 km elevation profile. Assumes steady power, with no stops, braking or drafting. Rounded to the nearest minute.

The science behind the calculation

For each part of the stored profile, we solve the steady-state cycling power equation for speed, then add distance ÷ speed across the climb. Gravity uses rider + equipment weight; available power is W/kg × rider weight. This uses the profile’s distance and elevation together, without mixing in another route’s metrics.

Power × efficiency = gravity + rolling resistance + air resistance + bearing losses

The resistance equations are adapted from Martin et al. (1998), Validation of a Mathematical Model for Road Cycling Power. Air density changes with profile altitude using NASA’s standard-atmosphere model. This calculator’s adaptation has not been independently validated.

It predicts travel at the power you enter, including on descents. It does not model acceleration, cornering, braking, traffic, wind, changing weather or fatigue. At altitude, choose power you can sustain there: thinner air reduces drag, but this model does not predict its effect on your ability to produce power. Profile quality and assumed equipment settings also affect the result.

04 / On the ground