IRONMAN 70.3 · Tallinn · 8 Aug 2027
How to train for IRONMAN 70.3 Tallinn
Tallinn is sold on speed. The organiser calls the run one of the fastest in the world and says the course is known for its speed and flatness, a chance for personal records unless the wind plays a trick on you. All of that is true, and it leads people to the wrong conclusion. Fast is not the same as easy. A course this flat gives you no climb to hide in and no descent to recover on, so you pedal every metre of the 89.5 km at the power you chose in the first ten minutes.
Across the three legs the file is 97.8 percent flat by distance. A Trained athlete's 5:45:25 is not decided by any feature of the road. It is decided by one number held for 2:57:40, and by whether the run still has anything to say after it.
By Kian Briel, founder. Analysed by engine 1, updated
What is actually on the road
The organiser's own course files, drawn the way the Event Analyzer draws a member's race.
- Swim1.9 km4 m upCourse file
- Bike89.5 km279 m upCourse file
- Run21.1 km137 m upCourse file
The swim is a single loop in Lake Raku, the organiser's new swim venue, 1.9 km of clear water over a sandy lakebed. The lake averages 6.4 m deep and reaches 18.7 m. From the exit it is about 300 m to Transition 1 on Karuse and Sinirebase streets, beside the lake.
Out of transition the bike heads away from the city towards the southern villages. It comes back via the Tutermaa area towards Tallinn and Unibet Arena, then goes out into the countryside again through Vääna and Tutermaa before finishing at Transition 2 in front of Unibet Arena. There are 4 aid stations on the way.
Transition 2 sits right next to the finish line, and the run starts from there. It is two laps of 21.1 km with views of Tallinn Bay, 8 aid station points, and a finish in front of Unibet Arena. The competition centre is by the Baltic Sea.
The profile is almost empty. The bike climbs 279 m in total and holds exactly one rise of 3 percent or steeper, 414 m at 3.6 percent near kilometre 49. Either side of it are two unbroken flat stretches, 41 km from the start and 35.5 km after the rise. The file's lowest ground, 7 m, comes twice, between kilometres 42 and 48 and again in the last 5 km. The run climbs 137 m, yet it holds only one ramp worth the name, 224 m at 5.8 percent, which you meet once on each lap.
Course shape by distance
- Flat 98%
- Climbing 1%
- Descending 1%
The longest stretches
- Bike, flat41 km45% of the bike
- Bike, flat35.5 km39% of the bike
- Run, climbing0.22 km1% of the run
Each row is one unbroken stretch of the course that keeps the same shape the whole way. The number is how much of that leg you spend inside it, and it comes out the same whether you are fast or slow.
What this course asks of each leg
Twelve training dimensions scored for each leg against its own course, the way the Event Analyzer scores a member's race.
On the bike, aerobic endurance and muscular endurance lead, and nothing on the road breaks them up. The demand model scores them 85 and 81, with threshold capacity at 70 and aerobic durability at 66 behind them. The bike fills 51 percent of a Trained athlete's day, so the five largest demands on the whole course are all bike demands. The run's pair reads 85 and 82, and the swim's 85 and 81.
What is missing tells you as much. High-intensity capacity scores 42 on the bike and strength and force 40, both low, because nothing on this road asks for a surge or for force against a gradient. When the engine compiles a session from this bike file it does not return intervals at all. It returns 60 minutes continuous in Zone 4 with stable output, between a warm-up and a cool-down. That is the leg in miniature. On the swim, technical skill scores 66, the highest skill score anywhere on the course.
Put the reference times side by side. The Trained band swims 38:09, rides 2:57:40 at 182 W from an input of 3.03 W/kg at 75 kg, and runs 1:59:36. Of that ride, the pacing table gives about a minute and a half to the one climb and a minute to descents. Everything else is flat road. The Competitive band finishes in 5:01:47, riding 2:37:10 at 249 W and running 1:41:38 from 4:20 /km threshold pace. On a course with no terrain to exploit, that gap is made of sustained power and a run that survives it.
The air has been mild. The organiser logged highs of 20 C in 2026, 19 C in 2025 and 24 C in 2024, and lows between 11 C and 13 C. Wind is the variable the organiser itself warns about.
- Aerobic endurance85
- Muscular endurance81
- Threshold capacity70
- Technical skill66
- Aerobic durability65
- Threshold durability65
- Fueling resilience55
- High-intensity capacity40
- Anaerobic capacity25
- Strength / force20
- Environmental resilience15
- Sprint power5
Nymiva reads what you can already show, from your own data
Connect your training history and the Focus Lab scores the same twelve dimensions this course demands against where you sit today. The gap between the two is what you train.
- MeasuredFrom your thresholds and testsThreshold power, threshold pace, critical swim speed and field tests you have done. The dimensions they can carry are scored directly.
- EstimatedFrom your training historyConnected activities are read for what they prove: long efforts, late-session fade, repeated hard work, fueling on long days. Each score says how it was read.
- ProxyFrom a stand-in, and named as oneWhere only an indirect signal exists, the score carries the proxy it came from and a lower confidence, never a number dressed as a measurement.
- UnmeasuredHonestly blankA dimension nothing in your data can answer stays unmeasured. It is never a zero, and the plan does not pretend to know it.
Every dimension ends in one word
- Develop the course asks more than you can show
- Maintain close enough to hold at the minimum dose
- Covered nothing to build here
- Unmeasured the course needs it, your data cannot say yet
Nymiva scores twelve dimensions for the course and the same twelve for the athlete. The course is read from the organiser's files. The athlete is read from their thresholds and connected training history, with every score noting what it came from and how far to trust it. A dimension becomes a gap only when the course asks for more than the athlete can show, and gaps are weighted by the share of race day they cover. Here the bike covers 51 percent and the swim 11 percent, which settles most arguments about where the hours go.
This page carries no athlete data, so the season below rests on one assumption: the gaps sit where the demands are highest. From there it builds 24 weeks in 5 developmental blocks with a two-week taper at the end. Aerobic endurance leads the first block in all three sports. The second block moves the bike to aerobic durability, the run to threshold durability and the swim to technical skill. Threshold capacity leads the third everywhere, muscular endurance the fourth, and aerobic endurance returns for the fifth. A member's season starts from their own numbers instead, and will not look like this one.
Train the bike to protect the run
Which demands matter most across the whole race. A leg's demand counts for as much of the day as that leg takes, so a score of 85 on the bike outweighs the same score on the swim.
- 01Aerobic enduranceBike leg, 51% of the day85 × 51%44
- 02Muscular enduranceBike leg, 51% of the day81 × 51%42
- 03Threshold capacityBike leg, 51% of the day70 × 51%36
The bike takes 51% of the Trained reference band’s day, so its demands carry the most race weight. What the bike leaves in the legs is what the run gets.
Which demand gets a block, and when
The engine freezes one lead focus per sport on every developmental block, holds the rest at maintenance, and verifies before it reprioritises.
An illustration, not your plan. This page has none of your data, so the season below is the engine’s answer to one stated assumption: that your gaps line up with what IRONMAN 70.3 Tallinn demands. Your own season is built from your history, your thresholds, the days you can train and the races you have entered, and it will differ from this in its priorities, its sessions and its load.
- 01Run muscular endurance, a practice block4 weeks
- 02Run aerobic endurance, a development block4 weeks
- 03Bike muscular endurance, a practice block4 weeks
- 04Bike aerobic endurance, a development block4 weeks
In the order the allocator places them, general first, most race-like last.
- Week 1PrepPrep
A lead-in week. It develops nothing by design.
- Weeks 2 to 5Foundation 1Closes with a recovery week
- PriorityBike aerobic endurance
- PriorityRun aerobic endurance
- PrioritySwim aerobic endurance
- SupportRun muscular endurance
- SupportBike muscular endurance
- SupportSwim muscular endurance
- SupportBike threshold capacity
- SupportRun threshold capacity
- SupportSwim threshold capacity
- SupportBike aerobic durability
- SupportRun threshold durability
- SupportSwim technical skill
- Weeks 6 to 9Foundation 2Closes with a recovery week
- PriorityBike aerobic durability
- PriorityRun threshold durability
- PrioritySwim technical skill
- SupportBike aerobic endurance
- SupportRun aerobic endurance
- SupportSwim aerobic endurance
- SupportRun muscular endurance
- SupportBike muscular endurance
- SupportSwim muscular endurance
- SupportBike threshold capacity
- SupportRun threshold capacity
- SupportSwim threshold capacity
- Weeks 10 to 13Foundation 3Closes with a recovery week
- PriorityBike threshold capacity
- PriorityRun threshold capacity
- PrioritySwim threshold capacity
- SupportBike aerobic endurance
- SupportRun aerobic endurance
- SupportSwim aerobic endurance
- SupportRun muscular endurance
- SupportBike muscular endurance
- SupportSwim muscular endurance
- SupportBike aerobic durability
- SupportRun threshold durability
- SupportSwim technical skill
- Weeks 14 to 17Event shaping 1Closes with a recovery week
- PriorityRun muscular endurance
- PriorityBike muscular endurance
- PrioritySwim muscular endurance
- SupportBike aerobic endurance
- SupportRun aerobic endurance
- SupportSwim aerobic endurance
- SupportBike threshold capacity
- SupportRun threshold capacity
- SupportSwim threshold capacity
- SupportBike aerobic durability
- SupportRun threshold durability
- SupportSwim technical skill
- Weeks 18 to 21Event shaping 2Closes with a recovery week
- PriorityBike aerobic endurance
- PriorityRun aerobic endurance
- PrioritySwim aerobic endurance
- SupportRun muscular endurance
- SupportBike muscular endurance
- SupportSwim muscular endurance
- SupportBike threshold capacity
- SupportRun threshold capacity
- SupportSwim threshold capacity
- SupportBike aerobic durability
- SupportRun threshold durability
- SupportSwim technical skill
- Weeks 22 to 23PeakPeak
The taper. Load comes down toward the race, content stays specific.
- Week 24RaceRace
Race week.
Held at maintenance between blocks
- Runmuscular endurance, aerobic endurance, aerobic durability, threshold capacity, threshold durability
- Bikemuscular endurance, aerobic endurance, aerobic durability, threshold capacity, threshold durability
- Swimaerobic endurance, aerobic durability, threshold capacity, threshold durability, muscular endurance, technical skill
Touches scheduled by each capability’s own decay, at a fraction of its development dose, so earlier work is still there on race day.
The sessions the blocks are built from
One entry per kind of work the block trains, at the intensity that work is meant to be done at. Where the same work runs at several lengths, the entry shows the span it grows across rather than one entry per length.
- Foundation 1 · Weeks 2 to 575 to 240 min
150 to 210 min at Zone 2
BikePower, Zone 2Trains aerobic capacity - Foundation 1 · Weeks 2 to 540 to 270 min
180 to 210 min at Zone 3, then 30 min at Zone 4
BikePower, Zone 3Trains aerobic capacity - Foundation 1 · Weeks 2 to 535 to 120 min
90 min at Zone 2
RunPace, Zone 2Trains aerobic capacity - Foundation 1 · Weeks 2 to 550 min
4 x 1.5 min at Zone 3, 6 min easy between
RunHeart rate, Zone 3Trains aerobic capacity - Foundation 1 · Weeks 2 to 545 to 51 min
4 x 8 min at Zone 2, 1 min easy between
SwimPace, Zone 2Trains aerobic capacity - Foundation 1 · Weeks 2 to 547 to 81 min
3 x 1000 m at Zone 3, 0.3 min easy between
SwimPace, Zone 3Trains aerobic capacity
Sustained course race pressure
60 min at Zone 4
Compiled by the deterministic course compiler from the organiser’s file: the course’s one repeatable requirement, rehearsed at a dose the progression allows.
- Bike
- 85 min
- Trains threshold durability
- Supports aerobic durability
24 weeks, laid out backwards from race day
The shortest runway Nymiva builds for this event type, with its blocks, recovery weeks, taper and race week in place.
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- Prep
- Foundation
- Event shaping
- Peak
- Race
- Recovery week
Your own season carries these same phases on your own dates, with the load solved from your fitness and the days you can train, and it changes when your data does.
What each level does on the day
Reference finish times per peer band, the pacing plan the model holds each band to, and where the day is decided.
| Band | Swim | Bike | Run | Finish |
|---|---|---|---|---|
| Recreational2:11 /100m critical swim speed · 2.47 W/kg at 75 kg · 6:08 /km threshold pace | 0:45:01 | 3:12:51 | 2:23:50 | 6:31:42 |
| Trained1:51 /100m critical swim speed · 3.03 W/kg at 75 kg · 5:06 /km threshold pace | 0:38:09 | 2:57:40 | 1:59:36 | 5:45:25 |
| Competitive1:36 /100m critical swim speed · 4.15 W/kg at 75 kg · 4:20 /km threshold pace | 0:32:59 | 2:37:10 | 1:41:38 | 5:01:47 |
| Elite1:26 /100m critical swim speed · 5.27 W/kg at 75 kg · 3:50 /km threshold pace | 0:29:33 | 2:23:32 | 1:29:54 | 4:32:59 |
Pacing plan
- 0 km0%30.8 km/h1:19:50
- 41 km-5.6%56.6 km/h0:16
- 41.2 km0%30.8 km/h14:33
- 48.7 km3.6%16.2 km/h1:32
- 49.1 km0%30.8 km/h1:09:10
- 84.6 km-3.6%48.1 km/h0:44
- 85.2 km0%30.8 km/h8:26
- Run: reach 4:20 /km and this course gives back 43:38.
Where it is decided
After kilometre 49, on the second long flat.
The first 41 km feel easy whatever you do, because fresh legs hide the cost. The engine gives that opening stretch 45 percent of the bike leg. Then comes the only rise, so gentle at 3.6 percent that most riders will barely register it, and then 35.5 km of flat road that holds another 39 percent. That second stretch is where the bill for the first one arrives. There is no hill to justify slowing down and no descent to spin out the legs. Either you are still holding 182 W, or you are quietly losing it in every kilometre.
The run is shaped the same way. Two laps, one short ramp of 224 m at 5.8 percent per lap, and flat road for almost all the rest. From an input of 5:06 /km threshold pace, the Trained reference runs 1:59:36. A runner who arrives with the bike ridden evenly can hold that on road like this. A runner who spent the first 41 km will feel the ramp on the second lap as if it were a mountain.
Getting it wrong
Riding the opening like a time trial. The road out of the city is flat, the field is fresh, and there is nothing to meter the effort against. It feels like free speed. It is borrowed from the 35.5 km after kilometre 49.
Training for a course with rest in it. Most training rides are broken into pieces by junctions and hills. The Tallinn bike file holds one rise in 89.5 km. If the longest unbroken block in your training is twenty minutes, a flat 41 km will find the gap, which is why the engine's session for this course is an hour in Zone 4 with nothing between the warm-up and the cool-down.
Treating the aid stations as optional. With 4 on the bike and no climbs to slow you down, you drink and eat at speed and in position. Fueling resilience scores 55 on both the bike and the run, and on a course this steady it is the demand people forget until the second lap.
Conditions on the day
- 2026high 20 C, low 13 C
- 2025high 19 C, low 11 C
- 2024high 24 C, low 11 C
From the organiser’s own records. Not a forecast.
Every session is a claim, every block is a test
A plan is not a calendar. Each key session states what it trains and how that is checked, and each block ends with a public verdict before the next one is chosen.
What a block promises
Bike aerobic endurance moves from your baseline to a stated target by the end of Foundation 1
- The baseline is your measured score when the block starts. The target is the score the model predicts for it.
- Verified at the block’s recovery week, by a field test or a refresh of the supply read from your history.
- Confidence rises by agreement between independent signals, never by one metric crossing a line.
- A block that misses its target is a public miss. The next block is chosen from what was proven, not from what was planned.
- 01Stimulus achievedThe work landed in the zone the session named, for the dose it named.
- 02Partially achievedSome of the work landed. The session banks what it can prove.
- 03Not achievedThe load may have been there. The stimulus was not, so nothing is banked.
- 04Data insufficientNo usable stream. The session is neither credited nor blamed.
- Session verified
- Progression banked
- Block verified
- Priority reassessed
- Plan adapted
Your numbers, this course
Analyze IRONMAN 70.3 Tallinn against my fitness
The same simulation and the same Focus Lab read, on your thresholds instead of a band’s. Three numbers give a finish estimate and a partial read. A connected history gives the whole table.
The first 14 days are free.
- Trained band finish
- 5:45:25
- Of the day on the bike
- 51%
- Dimensions scored per leg
- 12
- Season runway shown
- 24 wk
Questions people ask
- Is the IRONMAN 70.3 Tallinn bike course flat?
- Yes. The organiser tags it Flat, and the 89.5 km file climbs 279 m in total. It holds a single rise of 3 percent or steeper, 414 m at 3.6 percent near kilometre 49. Most of the rest sits in two long flat stretches of 41 km and 35.5 km.
- Where is the IRONMAN 70.3 Tallinn swim?
- In Lake Raku, on a single loop. The organiser describes clear water and a sandy lakebed, with an average depth of 6.4 m and a maximum of 18.7 m. Transition 1 is on Karuse and Sinirebase streets, about 300 m from the swim exit.
- What water temperature should I expect in Lake Raku?
- The organiser publishes no water temperature for any of the last three editions, and Lake Raku is a new swim venue. Air temperatures topped out at 20 C in 2026, 19 C in 2025 and 24 C in 2024. Check the water and the wetsuit rule in race week.
- How many aid stations are there at IRONMAN 70.3 Tallinn?
- The organiser lists 4 aid stations on the bike course and 8 aid station points on the run, which is two laps of 21.1 km finishing in front of Unibet Arena.
Course data from the organiser’s published files, analysed 23 Sept 2026 by engine 1, demand model 4. Reference times are simulated for a peer band at a stated reference athlete and are not a prediction for anyone. Nothing on this page is medical advice.
IRONMAN® and IRONMAN 70.3® are registered trademarks of World Triathlon Corporation. Nymiva is an independent training platform and is not affiliated with, sponsored by or endorsed by World Triathlon Corporation. Course data is read from the organiser’s public course pages for the purpose of describing the event.