Middle-distance triathlons: 7 of the UK’s best half-irons for beginners

Half iron, Ironman 70.3, middle-distance, half-Ironman… whatever you want to call it, 113km racing is on the rise. And it’s an achievable and hugely-rewarding experience, yet comes in as far more manageable and less all-consuming than full iron-distance racing.

Happily, like their bigger siblings, they invariably take place in spectacular settings, from stately homes to the rolling hills of Shropshire and more gorgeous lakes than you can poke a set of aerobars at.

So, onto our UK top seven, which we’ve rated in terms of elevation gain, water temperature, cost and cut-off times. Where possible, we’ve also ranked them according to average finishing time and what proportion of triathletes DNF.

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All the swim legs take place in lakes, which we think is the optimum body of water for beginners, and the perfect total bike elevation is seen as 500m over the 90km.

Best middle-distance triathlons for beginners

7. Ironman 70.3 Bolton

Bolton, Greater Manchester

8 June 2025

Of Ironman’s UK-based logistically impressive and slickly run events, it’s 70.3 Bolton that edges Weymouth as the pick for beginners due to the calm and warm lake swim (although the latter also has much to recommend it for 113km novices, especially the flat seafront run leg).

The event is Ironman’s only event in northern England after the organisation decided to consolidate its offering, scrapping both Ironman 70.3 Staffordshire (which was previously on this list) and Ironman UK.

The 70.3 Bolton races consists of a single loop 1.9km swim in Pennington Flash Country Park’s lake before a rolling 90km bike (with 800m+ elevation gain) through the countryside to the south west of Bolton.

The half marathon run takes athletes onto the streets of Bolton and Queen’s Park.

6. Cardiff Triathlon Legend 70.3 Triathlon

Cardiff, Wales

22 June 2025

The middle-distance Cardiff ‘Legend’ 70.3 triathlon was introduced to Cardiff Triathlon in 2022, which is run by Always Aim High Events (who also organise the Slateman Tri, among others).

It’s particularly beginner friendly as the 88km bike is entirely on closed roads through the city, while a total elevation gain of 450m isn’t too bad either. But before that, the 1,900m swim takes place in the calm waters of Cardiff Bay.

Following the bike, the 21.8km run takes place over a flat out-and-back route that you’ll complete five times, allowing you to see the sights of Cardiff Bay along the way.

5. The Gauntlet at Cholmondeley Castle

Cholmondeley, Cheshire

21-22 June 2025

The Castle Triathlon Series organisers are famous for catering for beginners to triathlon, and their middle-distance 113km Gauntlet races, while naturally tough, extend this novice-friendly approach.

While Hever and Castle Howard take the lion’s share of acclaim in the Castle Tri Series, here we’ve opted for the Cholmondeley leg of the series due to its flatter bike course and warmer lake than Hever.

The race begins with a two-lap swim in the Deer Park Mere before heading off out of the estate on a three-lap 30km course around the length and breadth of the Peckforton Hills, circumnavigating the National Trust’s Bickerton Hill en route back to the estate. The 10.5km looped run takes in fine views of Cholmondeley Castle before a finish in front of the castle.

4. Outlaw Half Holkham

Holkham, Norfolk

5-6 July 2025

Race organisers OSB topped our iron-distance for beginners list with the original Outlaw in Nottingham, and their middle-distance races ain’t bad for the newcomer to 113km racing as well.

Out of the two Outlaw Halfs, we’ve gone for the later-in-the-season Outlaw Half Holkham (it’s easy to get a race spot as well) held at the Holkham Estate in Norfolk.

The 1.9km single loop swim uses the 18th century hall as backdrop, before the single loop bike course takes in coastal roads, quiet country lanes and some faster roads.

Further beginner-friendliness comes in the form of the on-site camping for competitors and their family and friends, as well as OSB’s proven athlete care from registration to race day.

3. The Vitruvian

Rutland Water, Leicestershire

14 September 2025

From UK tri legend Mark Shaw, the Vitruvian has long welcomed athletes to the beautiful setting of Rutland Water in the East Midlands for a middle-distance classic.

After a swim in the calm Rutland Water, the two-lap bike course is rolling with one big climb, the Rutland Ripple, to contend with. The flat and mixed-terrain run around the lake climaxes with a well-spectated finish line creating a party atmosphere.

2. UK Ultimate Half Triathlon

Dearnford Lake, Shropshire

29 June 2025

The numbers of the UK Ultimate Triathlon may be in the tens rather than thousands, but that’s all part of the draw of this low-key half iron experience. Like its UK Ultimate full triathlon, which we voted as one of the best iron-distance races for beginners, this features a calm multi-lap swim, flat bike and run courses and a minimal DNF rate.

“There’s no hassle or stress at the UK Ultimate,” says UK age-group legend Anthony Gerundini. “The low-pressure environment should quell any race nerves. With the accompanying iron distance race earlier that day, the race has enough buzz to be exciting, but isn’t so big you just become a number to be herded. You get loads of chances to visit the aid stations. High fiving and mutual encouragement is mandatory! Everyone has a smile on their face.”

1. Cotswold Classic

Ashton Keynes Water Park, Gloucestershire

13 July 2025

Much of the appeal for newcomers of the Cotswold Classic will be the low-key, manageable logistics, which combine with the beginner-friendly course in the Ashton Keynes water park.

Like its Cotswold 113 sibling, the swim takes place in calm, clear and predictable waters and sighting is easy due to the large buoys and several landmarks. Onto the one-lap bike course and there are some gentle climbs in store as the course weaves through traditional Cotswold villages.

Athletes will experience a mix of tarmac and hard pack pathing for the half marathon run, which takes in lakeside paths and local village routes before finishing back close to the lakeside transition in the finishers area.

There’s also a refreshingly relaxed approach to the cut-offs, as race organiser Graeme Hardie explains. “Although we have an ‘official’ overall cut off of 8:30hrs, in reality we’re very flexible with it and as long as the competitor hasn’t gone to the pub on the way around for a 2hr carvery dinner, we’ll keep the finish line open for them within reason.

“We don’t have specific swim and bike cut off’s and the water safety crew will allow you as long your like in the water as long as you’re not a danger to yourself, and the bike course police and aid stations will start to wind down around 6hrs from the start of the race, but the competitor is welcome to continue.”

And to reduce any race-morning stress further (providing you don’t mind sleeping in a tent before a race), there’s also camping available in the field 100m from transition.

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