Caerphilly Mountain: Cycling Climb

The climb

About Caerphilly Mountain

Collections

Simon Warren’s Another 100 Greatest Cycling Climbs

Mountain Road climbs south from Caerphilly towards the ridge separating the town from Cardiff. This northern approach gives the ascent a different setting from the remote lanes of the Welsh uplands: the starting point belongs to the town, and the height comes quickly as the road leaves it behind. Over about 1.5 kilometres, the recorded climb gains 120 metres. Its finish is on the road across the hillside, below the mountain's physical summit.

The lower stretch is relatively restrained, but the gradient soon strengthens. Most of the effort falls in the middle of the ascent, where successive portions of road gain height much faster than the opening. There is some relief higher up, though the easing remains a climb rather than a level run to the end. The profile gives a short journey out of town a substantial central challenge. Caerphilly Mountain is direct, compact and harder in its middle than its start suggests.

01 / The ascent

Elevation profile

Start 121 m · Summit 243 m

Gradient by distance1.47 km / 122 m gain

0 km0.3 km0.6 km0.9 km1.2 km1.5 km

02 / The numbers

Climb statistics

Distance: 1.47 km
Elevation gain: 122 m
Average gradient: 8.3%
Climb category: 4
Start elevation: 121 m
Summit elevation: 243 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: 10.6 km/h

Based on the 1.47 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