London T100 Triathlon Race Guide: How to Master the Docklands Swim, Fast Bike and London Finish
- Jul 23
- 7 min read
By Nick Harris BA (Hons), Speedy Swimming
The London T100 Triathlon is one of the most unique races on the global triathlon calendar.
Unlike traditional triathlons held in rural locations, London T100 brings long-course racing into the heart of one of the world's most famous cities.
With a 2km swim, 80km bike and 18km run, it sits between Olympic distance and a traditional 70.3 — making it the perfect challenge for athletes stepping up to longer racing.
But don't underestimate it.
The London course rewards athletes who can stay calm, pace intelligently and execute every discipline.
London T100 Race Day Tips: The Small Details That Could Make a Big Difference
The London T100 looks like a fast, straightforward course.
A city race. Flat roads. A dock swim. A huge crowd.
But those same things create some unique challenges.
The athletes who perform best won't just be the fittest — they'll be the ones who understand how to race the course.
Here are some key areas to think about before race day.
Swim: Master the Royal Victoria Dock
The London T100 swim is very different from a typical lake or sea swim.
The water is enclosed, the course is compact, and with a large field of athletes, positioning becomes extremely important.
A few things to consider:
Don't waste energy fighting for space
The first few hundred metres can feel chaotic.
Avoid getting caught in the middle of the pack where you are constantly adjusting your stroke.
Find your rhythm early.
A calm swimmer will usually gain time on athletes who start too aggressively.
Get comfortable swimming close to others
T100 racing rewards athletes who can draft and stay relaxed in a group.
Practise:
swimming behind another athlete
holding your line
sighting without losing rhythm
Open water confidence is a skill, not just fitness.
Sight early and often
An urban swim can be deceptive.
Buildings, reflections and crowds can make landmarks harder to judge than you expect.
Good navigation saves energy.
Swimming straight is free speed.
Bike: The Fastest Course Can Be the Most Dangerous
A flat bike course feels easy.
That is exactly why athletes get caught out.
When there are no major climbs, there are fewer natural moments to recover — meaning pacing and efficiency become even more important.
The goal:
Arrive at T2 ready to run.
Stay aerodynamic
On a flat course, your position matters.
Small improvements in:
posture
relaxation
consistency
can create significant gains over 80km.
But being aero is only useful if you can maintain it comfortably.
Avoid unnecessary surges
The temptation will be to chase every rider who passes you.
Don't.
A fast T100 bike split comes from:
smooth power
controlled effort
patience
Not repeated attacks.
Ride for the final 18km
The bike is not the event.
It is your preparation for the run.
The athletes who run well will be the ones who resisted the temptation to prove their fitness on the bike.
Run: Use the Atmosphere, Don't Let It Control You
Running through London with crowds around you is an incredible experience.
But it can also be your biggest enemy.
The atmosphere makes you feel faster than you really are.
The first few kilometres may feel effortless.
That is when discipline matters most.
Start slower than you think
The first 5km should feel controlled.
You should feel like you are holding back.
The race begins when fatigue arrives — not when the crowd sends your adrenaline levels up.
Break the run into sections
Instead of thinking about the whole distance:
Settle into rhythm early
Focus on fuelling and hydration
Build through the second half
A smart final 5km is where places are won.
The Biggest London T100 Lesson
This race will reward athletes who are patient.
The swim rewards calmness.
The bike rewards discipline.
The run rewards restraint.
The best preparation is not about doing more.
It is about arriving on race day knowing exactly how to execute.
Swim Strategy
Start Position
Choose your starting position carefully.
If you are confident:
Start closer to the front.
Find faster swimmers to draft.
If you are nervous:
Start slightly wider.
Avoid being caught in the washing machine.
The first few minutes should feel controlled.
Do not turn the opening 500m into a sprint.
Drafting
The swim is a great opportunity to save energy.
A good draft can:
Reduce effort
Improve speed
Help you settle into rhythm
However:
Don't blindly follow feet.
You still need to sight.
A swimmer going the wrong direction is simply a slower route.
Training Session: T100 Swim Preparation
Race Rhythm Session
400m easy
8 × 100m:
Odd = race pace
Even = relaxed
4 × 200m continuous:
Sight every 6–8 strokes
300m easy
Focus:
Smooth effort.
Not maximum speed.
Transition One: Excel Centre Advantage
One of the unique aspects of London T100 is the indoor transition environment at ExCeL London.
This creates a different experience from a traditional outdoor transition area.
Practise your routine:
Know where your bike is located.
Keep equipment simple.
Avoid unnecessary kit changes.
Stay calm.
A smooth transition beats a rushed one.
The Bike: Fast, Flat and Easy to Overcook
The London T100 bike course is designed to be fast.
That is what makes it dangerous.
A flat course feels easy.
Your heart rate is controlled.
Your speed is high.
You feel amazing.
This is when athletes make mistakes.
The Biggest Bike Mistake
Riding above your sustainable effort because the course feels fast.
Remember:
You still have an 18km run.
The best athletes are not the ones who produce the biggest bike split.
They are the ones who arrive at T2 ready to run.
Bike Pacing Strategy
First 20km
Settle.
Ignore people flying past.
Middle section
Find your rhythm.
Stay aerodynamic.
Fuel consistently.
Final 20km
Prepare for the run.
Increase cadence slightly.
Do not empty the tank.
Wind Management
Even flat courses can be challenging.
London roads can be exposed.
Ride effort, not speed.
Into a headwind:
Stay aero.
Keep power steady.
With a tailwind:
Avoid chasing speed.
Maintain your effort.
Consistency wins.
Bike Training for London T100
Long Race Pace Ride
2–3 hours:
Include:
Long periods at race effort
Aero position practice
Nutrition practice
Finish with:
20-minute brick run.
Threshold Intervals
Warm up:
20 minutes
Main set:
4 × 8 minutes hard
4 minutes recovery
Cool down.
Build the ability to respond when the race gets harder.
Transition Two: Switch From Cycling to Running
The best long-course athletes practise transitions.
Before leaving the bike:
Drink.
Spin your legs.
Relax your shoulders.
Mentally reset.
The race changes here.
The Run: London Energy
The final 18km run is what makes this event special.
You are no longer just racing a stopwatch.
You are racing through London.
But the atmosphere can make athletes start too fast.
Run Strategy
First 5km
Control yourself.
Your legs will feel strange.
Your pace may feel slower than expected.
That's normal.
Middle 10km
Settle into rhythm.
Fuel.
Hydrate.
Use the crowd.
Final 3km
Now race.
This is where smart pacing pays off.
Brick Training
A key London T100 session:
Bike:
2 hours steady
Immediately:
45-minute run
First 15 minutes easy.
Then:
Build towards race pace.
Your body needs to learn the transition.
Equipment Checklist
For London T100:
✓ Tested wetsuit
✓ Comfortable goggles
✓ Aero position practised
✓ Race nutrition tested
✓ Elastic laces
✓ Lightweight running kit
Nothing new on race weekend.
Five Common Mistakes
Swimming too hard at the start.
Ignoring the river flow.
Riding too aggressively because the course is fast.
Starting the run too quickly.
Forgetting to practise transitions.
Final Thoughts
London T100 is not won by one outstanding discipline.
It is won by execution.
Swim calmly.
Ride efficiently.
Run progressively.
The athletes who enjoy the biggest success are usually those who arrive prepared for the unique demands of racing in the city.
Preparing for London T100?
At Speedy Swimming, I help athletes improve:
Open water confidence
Swim technique
Race-specific preparation
Triathlon performance
Whether this is your first long-course event or you are chasing a faster finish, preparing specifically for the demands of the course makes all the difference.
Nervous about your first T100 swim? Book a 1-to-1 open water session and learn how to sight, draft and swim efficiently in race conditions.
Ready to Take on London T100?
The London T100 is not just another triathlon.
It sits in that sweet spot between Olympic distance speed and full-distance endurance — fast enough that every mistake costs time, but long enough that pacing, nutrition and preparation become critical.
You don't need to train more.
You need to train smarter.
That is exactly why we created the Stealth Triathlon Coaching Tribe.
Train Like a Serious Age-Group Athlete
The Stealth Triathlon Coaching Tribe is our online coaching community for ambitious triathletes who want expert guidance, structured training and the support of like-minded athletes.
Inside the tribe you'll get:
✓ Structured swim, bike and run sessions✓
Training delivered through TrainingPeaks
✓ Race-specific preparation
✓ Open-water swim guidance
✓ Technique coaching
✓ Strength and mobility sessions
✓ Community support and accountability
✓ Expert feedback when you need it
Whether you're preparing for:
London T100
IRONMAN 70.3
IRONMAN
Challenge events
Your first middle-distance triathlon
The goal is the same:
Become a stronger, smarter and more confident triathlete.
Why Join a Coaching Tribe?
Most athletes don't fail because they lack motivation.
They struggle because:
training is inconsistent
sessions aren't structured properly
intensity is wrong
recovery is ignored
they don't know if they are improving
A coach removes the guesswork.
You simply follow the plan, execute the sessions and arrive at race day confident.
Join the Stealth Triathlon Coaching Tribe
Train with a community of athletes who are chasing their next challenge.
Whether your goal is completing your first T100 or achieving a personal best, you'll have the structure and support to get there.
Ready to take your racing seriously? Join the Stealth Triathlon Coaching Tribe and train with a structured plan built around your goals.
Join the Stealth Triathlon Coaching Tribe today.
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