Oysho Cardiff Half Marathon: Course, Route Profile & Map

Course & Elevation

You start on Castle Street, directly outside Cardiff Castle. The opening kilometres run south past the Principality Stadium and Cardiff City Stadium with the road easing down to seven or eight metres above sea level. At kilometre five Penarth Road rears up into the first ramp of the day, a good twelve metres of climb, before the course drops back towards Penarth Marina.

At kilometre 7.5 you turn onto the Cardiff Bay Barrage, the causeway that separates the bay from the Bristol Channel. Some one and a half kilometres of open water on both sides, almost no spectators, and wind. The route then runs through the middle of the Bay quarter, past the Norwegian Church, the Senedd and the Wales Millennium Centre. From kilometre 7.7 to 12.6 the course stays between seven and ten metres – the fastest stretch of the race.

From kilometre 13, on the way back into the city, the course climbs imperceptibly from about ten metres to 27. Between kilometres 16.5 and 19 you make a full circuit of the lake in Roath Park, and by then the crowds are deep – residents have been handing out sweets since mile ten. At kilometre 19.2 Fairoak Road delivers the last short ramp, then King Edward VII Avenue falls gently to the finish at the Civic Centre in Cathays Park. That is where the 27,500 places of Wales' largest road race come to an end – it is also the country's largest fundraising event, with more than 120 charities collecting over three million pounds here every year.

Pacing Strategy

Flat here means something specific: just under 78 percent of the route sits in the level band, and not a single section rates as a classified climb. This is a race you run on even splits, not on managing your legs uphill. With 27,500 starters in two waves the opening kilometres are crowded, but Castle Street is wide – skip the weaving and use the first two or three kilometres to settle into goal pace. The Penarth Road ramp at kilometre five arrives while you still feel fresh, which is exactly why it is the first trap.

On the barrage from kilometre 7.5 it is not the gradient that decides anything, it is the wind. The causeway is completely unsheltered out over the water, with no buildings and next to no spectators. Tuck into a group here rather than pushing into the wind alone. The Bay quarter that follows, up to kilometre 12.6, is the flattest part of the course – let it run.

The race is decided in the final third. From kilometre 13 the course gains around 20 metres spread over six kilometres: a climb you cannot see, but one that eats pace. Bank the quick first half as a time cushion and you will arrive at Fairoak Road, kilometre 19.2, with nothing left. Hold your rhythm deliberately through the Roath Park lake loop, and the gently falling run-in to Cathays Park will carry you home.

Training plan for Oysho Cardiff Half Marathon: 12-week build

As an age-group runner, expect a race of 70 minutes to a good two and a half hours; the cut-off is four hours, and sail-flag pacers from 1:30 to 4:00 run in every start pen. The effort is purely aerobic and unusually uniform: with no real climbs there is no change of terrain to unload the muscles or break your rhythm for you. On a course like this you hold the pace by yourself.

Preparation should therefore centre on sustained speed on the flat: weekly threshold runs of 20 to 40 minutes and goal-pace blocks of three to eight kilometres inside your long runs. Progressive long runs that put race pace at the end reproduce exactly what Cardiff demands over its closing third.

That closing third asks for two things a flat course usually does not: running a barely perceptible six-kilometre rise without losing pace, and having strength for one short ramp at kilometre 19. Put gently rising sections at the end of your long runs, and run a few short hill efforts out of full race pace rather than from a standing start.

Early October in Cardiff is mild – the 2025 race saw around 16 degrees – but the city sits on the coast, and rain and wind off the Bristol Channel are realistic. Train deliberately in wind on open ground so the barrage does not catch you out, and test your wet-weather kit in a tempo session beforehand. Aid comes roughly every five kilometres as a 330 ml bottle, with gels on course – practise drinking from a bottle on the move, or every station costs you seconds.