Triathlon in London and the UK: an independent guide
A triathlon is a swim, a bike ride and a run raced back to back, with the clock running through the changes. Most people in the UK start with a sprint: 750 metres of open water (or 400 metres in a pool), 20 kilometres on the bike and a 5 kilometre run.
Triathlon distances in the UK
The distances British Triathlon sets for age-group racing, shortest first. Age is your age on 31 December of the race year.
| Distance | Swim | Bike | Run | Minimum age |
|---|---|---|---|---|
| Super sprint | 250 m | 10 km | 2.5 km | 15 |
| Sprint (pool) | 400 m | 20 km | 5 km | 15 |
| Sprint (open water) | 750 m | 20 km | 5 km | 15 |
| Standard (Olympic) | 1,500 m | 40 km | 10 km | 17 |
| Middle (70.3) | up to 3,000 m (usually 1,900 m) | up to 90 km (usually 90 km) | up to 21.9 km (usually 21.1 km) | 18 |
| Long (full distance) | up to 4,000 m (usually 3,800 m) | up to 200 km (usually 180 km) | up to 42.2 km | 19 |
Source: British Triathlon Competition Rules 2026, Appendix A, checked 6 October 2026. Organisers can set distances within these limits, so check the race page.
2027 races with a confirmed date
Only dates published on each organiser's own website as of 6 October 2026. Many UK races announce their next date later in the winter.
- Jan
- Feb
- Mar
- Apr
- May
- 23 May Outlaw Nottingham HalfHolme Pierrepont, Nottingham
- Jun
- 5-6 Jun Supertri Blenheim PalaceWoodstock, Oxfordshire
- 6 Jun IRONMAN 70.3 BoltonBolton, Greater Manchester
- 13 Jun Royal Windsor TriathlonWindsor, Berkshire
- Jul
- 3-4 Jul Outlaw Holkham weekendHolkham, Norfolk
- 11 Jul IRONMAN 70.3 SwanseaSwansea
- 25 Jul Outlaw Nottingham (full)Holme Pierrepont, Nottingham
- Aug
- 21-22 Aug London T100 TriathlonRoyal Docks, London
- Sep
- 12 Sep IRONMAN 70.3 WeymouthWeymouth, Dorset
- 25-26 Sep Hever Castle TriathlonHever, Kent
- Oct
- Nov
- Dec
Sources and race details: UK triathlon calendar. IRONMAN and IRONMAN 70.3 are trademarks of The IRONMAN Group; Tri Almanac is not connected with any organiser.
Your first triathlon, step by step
The order most first-timers follow. Each step links to the guide that covers it.
- Pick a distanceSuper sprint or sprint is the usual start; a pool-based sprint avoids open water.
- Choose a raceUse the calendar and British Triathlon's event search.
- Sort your Race Pass£2 up to age 24 or £8 from 25 if you are not a Core or Ultimate member.
- Train for 12 weeksTwo sessions a week per sport, then add bike-to-run bricks.
- Practise open waterSupervised venues only, with a tow float and a bright cap.
- Pack your kitLay it out in transition order and rehearse the changes.
Training
Plans laid out as weekly structures you can fit around work, plus the session that joins the bike to the run.
- BeginnersTriathlon for beginners in the UK: choosing a first race, British Triathlon Race Pass and membership prices, minimum kit, a race timeline and where to train.
- Sprint planA 12-week sprint triathlon training plan for beginners: phases, sessions per week, a sample week, rest, taper, and what to do without a pool or front crawl.
- Olympic planAn Olympic triathlon training plan for athletes moving up from sprint: 12 to 16-week phases, weekly hours, a sample week, key sessions and how to taper.
- Brick workoutWhat a brick workout is, example brick sessions for sprint and Olympic triathlon, turbo trainer bricks, transition practice at home and common mistakes.
- What to wearWhat to wear for a triathlon, leg by leg: swim, bike, run and transition, pool or open water, cold weather, plus a full sprint triathlon kit checklist.
Train in London
Supervised open water, 50 metre pools and closed-road circuits, starting in East London. Each entry lists what the operator states.
- Open water in LondonOpen water swimming in London for triathletes: West Reservoir, Hampstead Heath ponds, Serpentine, Royal Docks and Beckenham, with rules and prices.
- West ReservoirWest Reservoir Centre open water swimming in Hackney: courses, tow float and hat rules, wetsuits, age limits, booking and prices checked October 2026.
- London Aquatics CentreLondon Aquatics Centre for triathletes: two 50 m pools at Queen Elizabeth Olympic Park, opening hours, booking, sessions to swim and other East London pools.
- VeloPark road circuitLee Valley VeloPark road circuit: a 1-mile floodlit closed circuit in Stratford. Hours, booking, rules, prices checked October 2026 and triathlon sessions.
- Cycling in LondonWhere to train on a bike in London: closed road circuits, Herne Hill Velodrome, Richmond Park cycling rules, Royal Parks speed limits and winter turbo sessions.
Kit in transition order
The kit guides follow the race: what you wear in the water, what waits in transition for the bike, and what you run in.
- Swim
- T1 and bike
- T2 and run
What a triathlon involves
Every triathlon follows the same order: swim, bike, run. Between the legs you pass through transition, a fenced area where your bike and kit wait on a numbered rack. The change from swim to bike is called T1 and the change from bike to run is T2. Both count towards your finishing time, which is why people practise them.
The swim is usually in a lake, a river, a dock or the sea, although many first races in the UK are pool-based. Open-water swims follow a course marked by buoys, and British Triathlon's rules decide whether wetsuits are compulsory, optional or banned according to the water temperature. Below 15.9 °C a wetsuit is compulsory; up to 1,500 metres it is banned above 22 °C for age-groupers up to 59. Our guide to UK triathlon rules has the full table.
Most UK age-group races are non-drafting: you may not sit in the slipstream of another rider. British Triathlon defines a draft zone 12 metres long behind each bike and gives you up to 25 seconds to pass through it.
Which distance to choose first
The table above sets out the distances in British Triathlon's competition rules. A super sprint or a pool-based sprint is the gentlest introduction: the swim is short, you can stand up in the pool and you do not need a wetsuit. An open-water sprint is the next step. After a season of sprints, many people move up to the standard distance, also called Olympic distance, and some go on to a middle-distance race such as an IRONMAN 70.3.
If you are starting from scratch, read how to start triathlon in the UK, then pick a plan: our 12-week sprint triathlon training plan is laid out as weekly structures rather than fixed workouts, so it fits around work and family.
Training for triathlon in London
London has more places to train for triathlon than it first appears, and several of them are in the east of the city. The London Aquatics Centre in Stratford has two 50 metre pools. West Reservoir in Stoke Newington offers supervised open-water swimming all year round, with a tow float provided. Lee Valley VeloPark, also in the Queen Elizabeth Olympic Park, has a floodlit one-mile road circuit closed to traffic, which is a safe place to practise holding a steady effort on the bike.
Each venue page lists what the operator states about booking, requirements and prices, with the date we checked. Venues change their timetables and prices, so confirm on the operator's own page before you travel. Start with open water swimming in London.
How we check what we publish
Tri Almanac is an independent guide published by Aigen Digital Marketing SL. Rules and distances come from British Triathlon's Competition Rules 2026. Race dates come only from organisers' own websites; if a 2027 date has not been published, we say so instead of guessing from past editions. Venue details come from the operators. Every page shows when it was checked and lists its sources.
We have not tested the products in our kit guides. They describe what to look for and what brands and UK retailers state, with prices and the date we read them. Some shop links earn us a commission, which never changes the price you pay. The details are on how we work.
Frequently asked questions
How long is a triathlon?
It depends on the distance. Under British Triathlon's rules a sprint is 750 metres of swimming, 20 kilometres of cycling and 5 kilometres of running, or a 400 metre swim if it is held in a pool. A standard (Olympic) race doubles that to 1,500 metres, 40 kilometres and 10 kilometres. Middle and long distance go up to a 4,000 metre swim, 200 kilometre ride and a marathon.
How old do you have to be to do a triathlon in the UK?
British Triathlon sets a minimum age for each distance, counted from your age on 31 December of the race year: 15 for super sprint and sprint, 17 for standard distance, 18 for middle distance and 19 for long distance. Junior races have their own categories. Some organisers set a higher limit for their race, so check the event page.
Do I need to join a club or British Triathlon to race?
No. You can enter most UK races without a club. British Triathlon permitted events require third-party liability cover: if you are not a Core or Ultimate member, you buy a Race Pass for that race, which costs £2 up to age 24 and £8 from 25 (checked 6 October 2026). Some entries include it.
Is this the East London Triathletes website?
No. Tri Almanac is an independent guide. East London Triathletes, the club that used this web address until about 2020, is still active and has its own website at eastlondontri.co.uk. We have no connection with the club, its members or its coaches, and we do not organise training or races.
Sources
- British Triathlon Competition Rules 2026 (April 2026), Appendix A and rule 4, checked 6 October 2026
- British Triathlon, Race Pass, checked 6 October 2026
- British Triathlon, Membership, checked 6 October 2026