“Excuse me, can I just go through my transition zone stuff to check I have everything?” the woman next to me asks, a nervous but excited look on her face – one that probably mirrored my own – as she tells me this is her first triathlon.

“Of course,” I reply. “This is my first Olympic-distance race too.”

Having only completed one sprint-distance triathlon in my very, very short triathlon career, I’m not exactly an expert, but that was the beauty of the moment – we’re both figuring it out together. Two first-timers about to take on the T100 Olympic-distance event.

Compared to my previous race in Hertfordshire, stepping into the T100 at London’s Excel feels like entering another world. Thousands of triathlon bikes are racked across the enormous transition zone, the bright blue lights of the iconic finish line can be seen from every corner of the hall, and the atmosphere is already building as crowds cheer for the full T100 athletes who’d set off earlier that morning.

It’s impressive. Intimidating, even. The butterflies flutter harder in my stomach.

The T100 event series, organised by the Professional Triathletes Organisation, is a premium global event associated with elite racing and serious age-groupers. So, how would a newcomer to the sport find the event in the heart of the UK’s capital city? There was only one way to find out, and that was to complete it myself.

Registration and pre-event information

Verdict: Beginner-friendly

Signing up is straightforward. I entered the event back in August 2025, giving myself almost a year to prepare, although the event had sold out by the time race weekend arrived. If you’re considering entering, it’s worth booking early.

One of the biggest positives of T100 as a first-timer is the communication in the lead-up to race day. Alongside emails about bike hire, wetsuit rental and nutrition, competitors receive a comprehensive 54-page Athlete Information Guide covering everything from course maps and transition layouts to race rules and aid stations.

As someone who likes to know exactly what to expect before arriving at an event, this was invaluable. Rather than spending the week before the race worrying about logistics, I could find almost every answer in one place. Knowing where I needed to be, what I needed to bring, and how race morning would work, removed a lot of unnecessary stress.

For experienced triathletes, that level of detail may simply be helpful. For beginners, it’s confidence-building.

The T100 swim

Verdict: Beginner-supported

If there was one discipline I was worried about before race day, it was the swim. I’d completed relatively little open-water swimming in training (a lesson learned for my next race) and spent weeks wondering whether I’d make the cut-off – more on that later. Like me, many beginners see the swim as the biggest barrier to entering a triathlon, so this was the moment that would determine whether the London T100 really felt welcoming to newcomers.

Thankfully, I needn’t have worried. Before entering the water, competitors are given a 10-minute swim briefing explaining the course, safety procedures and what to expect. A rolling start helps spread swimmers out, reducing the chaos that many first-timers fear. Meanwhile, lifeguards in kayaks line the course, regularly checking that competitors are okay or offering somewhere to hold on if needed. Less-confident swimmers could even request a white swim cap, making them easier for the safety team to identify.

That’s not to say the swim’s easy. A 1.5km open-water swim is still a significant challenge, and I appreciate that other athletes may have experienced the inevitable knocks and bumps that come with racing in open water. For me, though, I find I can settle into the swim course without the worry that someone would swim over me, switching between front crawl and breaststroke, like many others.

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The T100 bike

Verdict: Beginner-friendly, but technical

The bike course is undoubtedly my favourite part of the day. Racing on closed roads through central London, passing iconic landmarks such as the Tower of London and the Houses of Parliament, makes for a truly memorable experience – whether you’re racing as fast as possible or simply ticking off the kilometres one at a time.

That said, beginners shouldn’t mistake this “flat” course for an easy ride. There are plenty of tight corners and U-turns that demand focus, as well as a few spicy climbs over bridges and through tunnels that certainly get the legs working. Concentration is key – I even witness one rider fall after looking over to wave at supporters and catching the barriers.

The good news is that the course is extremely well supported. Volunteers are positioned throughout, alerting riders to upcoming hazards and areas where extra caution is needed, while clear signage helps guide you around the route. The only thing to keep an eye on is your laps. Make sure you know the requirements beforehand, as this information is outlined in the Athlete Guide.

• What is a good cycling pace?

The T100 run

Verdict: Beginner-friendly

A lap-based course can be both a positive and a negative. When you start your first lap knowing there are three more to come, it can feel slightly daunting. But once you settle into the rhythm, understand where the climbs are, where the aid stations are positioned, and start counting down from four laps to one, it becomes a real advantage.

For a beginner like me, I actually find the familiarity reassuring. Rather than feeling like you’re running into the unknown, you know what each section will bring, where you can take on fuel or water, and how far you have left to go (also thanks to a sign near the end of each lap telling you roughly what your smartwatch should be saying or when to go into the finish line). That predictability helps to make the final 10km feel much more manageable.

There are also two aid stations with toilets across the Olympic-distance run course. These are fully stocked with water, ice, snacks, gels, electrolytes and cola – something I really appreciate as temperatures rise during my run between 12pm and 1pm.

For beginners, having regular opportunities to refuel, cool down and take on fluids removes a lot of uncertainty. Knowing support was never far away made the final kilometres feel much more manageable.

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Cut-offs

Verdict: Could be improved for beginners

I’ll admit it, the cut-off times worried me more than any other aspect of the race. Judging by the discussions in the T100 London Facebook group, I wasn’t the only one.

I was placed into the final Olympic-distance wave, starting at 10:10am. To complete the full 40km bike course, riders had to reach the Westminster section by 11:35am. Miss that cut-off, and you could still finish the race, but your bike course would be shortened, and your result would be recorded as “unofficial”.

For weeks, I questioned whether I’d put down an ambitious predicted finish time I couldn’t live up to. Why had I been placed in the last wave? Would I make the cut-off for a race I’d been training for since January?

In the end, I did, but only by 10 minutes. However, I wasn’t the last swimmer out of the water, and cycling is arguably my strongest discipline. I also spoke to another competitor before the swim who was racing her third London T100. She told me she’d narrowly made the bike cut-off in previous years and was worried this year’s timings would be even more challenging.

I appreciate the organisers are working within the constraints of road closures in central London, and cut-offs are an unavoidable part of delivering an event of this scale. Nonetheless, if there’s one area that could be improved for beginners, it’s this. Being in one of the later Olympic-distance waves added unnecessary pressure before I’d even entered the water, and it’s easy to see why it became such a talking point among first-time competitors.

Logistics

Verdict: Beginner-friendly

Racing in London is surprisingly beginner-friendly thanks to the excellent transport links to the Excel Centre. The venue is easily reached via the Elizabeth line and DLR, with plenty of nearby hotels if you’re travelling from further afield. Parking is also available on-site and in the surrounding area.

Inside, everything was well organised. There were plenty of toilets, food and drink options, water refill stations, and volunteers on hand to answer questions. My only criticism was that the mechanics were located on the opposite side of the venue from transition. After discovering I had a flat tyre an hour before my wave, I found myself panic-speed-walking across Excel to get it fixed – not the ideal pre-race warm-up.

Atmosphere

Verdict: Extremely beginner-friendly

The atmosphere was second to none. From volunteers cheering as you left transition to spectators lining both the bike and run courses, there was encouragement at every stage of the race. The lap-based course on the bike and run meant supporters could see athletes multiple times, creating a lively atmosphere that never dipped and giving everyone an extra boost when they needed it most.

So, is the T100 event beginner-friendly?

Verdict: Yes, but it isn’t beginner-easy

Before arriving at the Excel on race morning, I wondered whether the London T100 would feel too big, too serious or too intimidating for someone completing only their second triathlon. Standing in transition surrounded by thousands of bikes, it certainly looked that way. But by the time I crossed the finish line, my view had completely changed. The organisation, support and atmosphere made for a brilliant race experience.

That doesn’t mean beginners should underestimate the challenge. A 1.5km open-water swim, 40km bike and 10km run is still a significant undertaking, and you need to arrive prepared. The cut-offs, particularly for those starting in later waves, are something to consider carefully and could be made more accessible for newer athletes.

However, with super-sprint, sprint, Olympic-distance and relay options available alongside the flagship T100 distance, there are plenty of ways to experience the event at a level that suits your own triathlon journey.

For me, as someone still relatively new to the sport, the London T100 proved that you don’t need years of triathlon experience to take on a big-city event.

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