Sulby Glen Road: Cycling Climb

The climb · Isle of Man

About Sulby Glen Road

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Simon Warren’s Another 100 Greatest Cycling Climbs

At Tholt-y-Will, the upper part of Sulby Glen Road leaves the glen and climbs towards the Bungalow on the A18. The recorded ascent starts here, well beyond Sulby village, taking in 4.5 kilometres of the A14. Trees and the winding glen road give the lower section a sheltered setting before the route gains the open hills above. Its roughly 290 metres of climbing are weighted towards the earlier part of the ascent.

The lower slopes and bends ask for the strongest sustained effort. Beyond them, the road becomes less steep but continues to gain height, trading the enclosed valley setting for a broader mountain outlook. The easing is enough to change the rhythm without turning the upper section into a flat approach. The finish is at the Bungalow road junction, beneath Snaefell. It is the transition from the glen to high ground that gives this climb its particular appeal.

01 / The ascent

Elevation profile

Start 124 m · Summit 413 m

Gradient by distance4.49 km / 292 m gain

0 km0.9 km1.8 km2.7 km3.6 km4.5 km

02 / The crux

Where it gets difficult

Choose a distance to find the steepest continuous section of the climb.

Steepest 500 m average

11.6%

Where to find it

1.00–1.50 km from start

Net height gained: 58 m
Section length: 500 m

The whole climb4.49 km

0 kmFinish

03 / The numbers

Climb statistics

Distance: 4.49 km
Elevation gain: 292 m
Average gradient: 6.4%
Climb category: 3
Start elevation: 124 m
Summit elevation: 413 m

Current weather

At the climb start

Loading weather…

Weather data: MET Norway

04 / 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

20 min

Power throughout: 225 W
Average speed: 13.2 km/h

Based on the 4.49 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.

05 / On the ground