IRONMAN 70.3 · Tours · 6 Jun 2027
IRONMAN 70.3 Tours Metropole - Loire Valley guide
The organiser calls Tours one of the fastest courses in France, and the file backs them up. 486 m of climbing across 110 km, 97 percent of the course flat by distance, a swim in a river and a finish line under a roof. People read "fast" and hear "easy".
A fast course is not decided by what it asks of you. It is decided by what it lets you get away with. Tours lets you get away with almost anything for the first half of the bike, and then it sends the bill to the second of the two loops of the run.
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 kmDistance only
- Bike87.4 km376 m upCourse file
- Run21.2 km110 m upCourse file
The swim is one rectangle in the Cher, a tributary of the Loire, 1.9 km in water the organiser logged at 22 C in 2026 and 22 C in 2025. The organiser promises spectators all around the river. A path leads from the water exit to the bike park, and the transition is indoors, bags, changing rooms and bikes under one roof.
The bike is a single loop along the banks of the Cher and out through the Touraine, past the region's castles, the Château d'Ussé among them, the one said to have inspired Sleeping Beauty. The organiser calls it 90 km. The file they publish measures 87.4 km and 376 m of climbing.
Read the profile in pieces. The first 43.6 km are one flat segment. A handful of small bumps around kilometre 45 follow, then another 16.3 km of flat road. Between 62.6 km and 69.4 km sits the only real cluster of rises on the course, three short climbs of 3.1 to 3.9 percent. A 696 m descent at 4.9 percent comes later, then 9.6 km of flat road back to transition.
The run is two loops along the Cher and across its artificial island, the Parc Honoré de Balzac, 110 m of climbing over 21.2 km. It ends indoors, in the Parc des Expositions de Tours.
Course shape by distance
- Flat 97%
- Climbing 1%
- Descending 2%
The longest stretches
- Bike, flat43.6 km48% of the bike
- Bike, climbing0.44 km1% of the bike
- Run, flat21.2 km100% 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.
Aerobic endurance and muscular endurance, then very little else. The demand model scores those two at 85 and 81 on the bike, with threshold capacity at 70 and the two durability scores at 66 behind them. Because the bike fills 51 percent of a Trained athlete's day, the five largest demands on the whole course are all bike demands. The run's own pair comes sixth and seventh at the same 85 and 81. The swim's pair reads 85 and 80 and ranks twentieth and twenty-first, since the swim is a ninth of the day.
Look at what the course does not ask. High-intensity capacity reads 46 on the bike, strength and force 41, anaerobic capacity 25. Ask the engine for a session built from this bike file and it returns four efforts of three quarters of a minute in Zone 5, one for each comparable climb, with more than seven minutes of easy riding between them. Three minutes of work, in 87.4 km. That is how little the terrain interrupts you.
The bands turn this into clock time. A Trained athlete swims 38:12, rides 2:55:22 at 182 W and runs 2:00:02, for 5:43:36. The Competitive band finishes in 5:00:09 from 4.15 W/kg at 75 kg, about 20 minutes quicker on the bike and 18 on the run. On a course this flat that bike difference is steady power and nothing else, 249 W against 182 W, held with no climb to hide behind.
One score stands out. Technical skill reads 54 on the run against 35 on the bike, and that is the run file's turns: two loops through a park and onto an island bend more often than a country road does. The weather asks little. The organiser logged highs of 23 C, 22 C and 21 C over three editions, and environmental resilience scores 15 on every leg.
- Aerobic endurance85
- Muscular endurance80
- Threshold capacity70
- Aerobic durability65
- Threshold durability65
- Fueling resilience55
- Technical skill55
- 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 reads the same twelve dimensions twice. The course's come from the file the organiser publishes. The athlete's come from their thresholds and their connected training history, and each score carries a note on what it was read from and how far it can be trusted. Only where the course asks for more than the athlete can show is there a gap, and gaps are weighted by the share of the day they fill. Here the bike is half the day and the swim a ninth of it, so a bike gap outweighs a swim gap of the same size more than four times over.
This page holds no athlete. The season on it takes the plainest assumption, that the gaps fall where the demands are largest, and lays out 24 weeks in 5 developmental blocks before a two-week taper. Aerobic endurance leads the first block in every sport. The second splits by sport, with aerobic durability leading on the bike and in the water while the run works on threshold durability. Threshold capacity leads the third block. Muscular endurance leads the fourth. Aerobic endurance comes back for the last block before the taper. A member's season starts from their own numbers, and it will disagree with this one wherever their numbers do.
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%43
- 02Muscular enduranceBike leg, 51% of the day81 × 51%41
- 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 Tours Metropole - Loire Valley 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
- SupportBike muscular endurance
- SupportRun muscular endurance
- SupportSwim muscular endurance
- SupportBike threshold capacity
- SupportRun threshold capacity
- SupportSwim threshold capacity
- SupportBike aerobic durability
- SupportRun threshold durability
- SupportSwim aerobic durability
- Weeks 6 to 9Foundation 2Closes with a recovery week
- PriorityBike aerobic durability
- PriorityRun threshold durability
- PrioritySwim aerobic durability
- SupportBike aerobic endurance
- SupportRun aerobic endurance
- SupportSwim aerobic endurance
- SupportBike muscular endurance
- SupportRun 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
- SupportBike muscular endurance
- SupportRun muscular endurance
- SupportSwim muscular endurance
- SupportBike aerobic durability
- SupportRun threshold durability
- SupportSwim aerobic durability
- Weeks 14 to 17Event shaping 1Closes with a recovery week
- PriorityBike muscular endurance
- PriorityRun 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 aerobic durability
- Weeks 18 to 21Event shaping 2Closes with a recovery week
- PriorityBike aerobic endurance
- PriorityRun aerobic endurance
- PrioritySwim aerobic endurance
- SupportBike muscular endurance
- SupportRun muscular endurance
- SupportSwim muscular endurance
- SupportBike threshold capacity
- SupportRun threshold capacity
- SupportSwim threshold capacity
- SupportBike aerobic durability
- SupportRun threshold durability
- SupportSwim aerobic durability
- 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
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
4× course-matched climbs
0.8 min at Zone 5, then 0.8 min at Zone 5, then 0.8 min at Zone 5, then 0.8 min at Zone 5, 7.3 min easy between
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
- 50 min
- Trains anaerobic capacity
- Supports strength force
- Supports muscular endurance
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
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- 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 | 0:45:05 | 3:10:21 | 2:24:21 | 6:29:47 |
| Trained1:51 /100m critical swim speed · 3.03 W/kg at 75 kg · 5:06 /km threshold pace | 0:38:12 | 2:55:22 | 2:00:02 | 5:43:36 |
| Competitive1:36 /100m critical swim speed · 4.15 W/kg at 75 kg · 4:20 /km threshold pace | 0:33:03 | 2:35:07 | 1:41:59 | 5:00:09 |
| Elite1:26 /100m critical swim speed · 5.27 W/kg at 75 kg · 3:50 /km threshold pace | 0:29:36 | 2:21:40 | 1:30:13 | 4:31:29 |
Pacing plan
- 0 km0%30.8 km/h1:24:52
- 43.6 km-3.2%46.3 km/h0:22
- 43.8 km1.1%25.5 km/h2:36
- 45 km-3.1%45.8 km/h0:25
- 45.3 km-0.2%31.8 km/h1:10
- 45.9 km3%18 km/h0:40
- 46.1 km-4.4%51.6 km/h0:14
- 46.3 km0.1%30.3 km/h32:20
9 more segments in the full plan.
- Run: reach 4:20 /km and this course gives back 43:27.
Where it is decided
In the first 43.6 km, before anything has happened.
That opening segment is 48 percent of the bike leg, the largest single block of time in the race apart from the run itself. No gradient changes your speed and no descent gives you a rest. The effort you choose on the first kilometre is the effort you carry for the rest of it, and the one you feel least. A rider holding 182 W and a rider holding a little more reach the first bump feeling the same, and a long way apart in what they have left.
The run then reads as one flat segment from the first metre to the last, and the engine gives it the whole of its own leg. There is nothing on it to blame. A Trained athlete runs 2:00:02 from an input of 5:06 /km threshold pace, and the second loop along the Cher is where a rider finds out which of those two bikes they rode. The Competitive band's 18 minutes on the run come from a faster threshold. They do not come from a harder start to the bike.
Getting it wrong
Most of the damage starts in the water. The organiser's own description has spectators all around the river urging you to go fast, and after the path to the bike park you roll out onto the flattest road of your season with fresh legs and nothing ahead that asks for restraint. Riding the opening segment on that excitement is the classic Tours mistake, and 43.6 km is a long way to pay it back.
The second mistake comes late in the loop. Past 62.6 km the road finally tilts, and after that much unchanging effort the three short rises feel like a chance to do something. The steepest is 441 m at 3.9 percent and costs 1.1 percent of the bike leg. Surging it buys nothing and spends what the flat 9.6 km into transition, and the run after them, will ask for.
The third mistake happens months earlier. Riders who prepare on rolling roads spend a good part of every ride coasting, and this course never lets them. Muscular endurance scores 81 on the bike, and on this road the pedals never stop for long, so practise long, unbroken, steady pressure on flat road. Hill repeats will not prepare you for 43.6 km without a single break in effort.
Conditions on the day
- 2026high 21 C, low 12 Cwater 22 C
- 2025high 22 C, low 15 Cwater 22 C
- 2024high 23 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 Tours Metropole - Loire Valley 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
- 5:43:36
- Of the day on the bike
- 51%
- Dimensions scored per leg
- 12
- Season runway shown
- 24 wk
Questions people ask
- How flat is the bike course in Tours?
- Very. The organiser describes a 90 km flat loop along the banks of the Cher, and the file they publish measures 376 m of climbing over 87.4 km. The steepest sustained rise is 441 m at 3.9 percent, inside a short cluster of rises between 62.6 km and 69.4 km.
- What water temperature should I expect in the Cher?
- The organiser logged 22 C in both 2026 and 2025, and has no water reading for 2024. The swim is a single rectangle in the river. The wetsuit decision is not on the organiser's course page, so check it in race week.
- How many loops is the Tours run?
- Two, for 21.1 km along the banks of the Cher and across its artificial island, the Parc Honoré de Balzac. The file climbs 110 m in total. The run finishes indoors in the Parc des Expositions de Tours.
- How long is the season on this page?
- The illustrative season runs 24 weeks, with five developmental blocks and a two-week taper. It is built from the course alone. A member's season starts from their own numbers and can be longer.
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.