IRONMAN 70.3 · Sandusky · 18 Jul 2027
How to train for IRONMAN 70.3 Ohio
The organiser sells Ohio as a first race or a personal best, and the brochure line is fair. You jump off a ferry into Sandusky Bay, ride a fast flat loop through farmland and run two laps of downtown Sandusky. What the brochure leaves out is what flat does to your judgement. With no hill to slow you down, nothing on the road tells you when you are overdoing it.
That is the whole problem here. The bike carries 180 m across 91.8 km, and the engine finds one flat stretch of more than 64 km in the middle of it. A Trained athlete's 5:50:06 is settled on that stretch, long before the run begins.
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.
- Swim1.93 kmDistance only
- Bike91.8 km180 m upCourse file
- Run21.4 km in 2 laps42 m upCourse file
Nobody forgets the start. You walk about 150 yards from transition at Paper District Marina to the Kelleys Island Ferry, The Carlee Emily, moored beside Jackson Street Pier. The ramp comes down to the water's edge and you jump off feet first, in a rolling start you seed yourself. Then it is one loop of 1.9 km in a protected corner of Sandusky Bay, finishing back at the marina.
The bike leaves Sandusky quickly and heads out through Erie and Sandusky Counties on rural farm roads, a single loop of 91.8 km. The organiser quotes approximately 820 feet of gain and calls it a flat course. The file measures less. The steepest sustained rise is 269 m at 3.3 percent, three kilometres in. The only other ramp of note is 364 m at 3 percent near kilometre 68, followed by two short drops of around 4 percent. Everything else is level road.
The run is 2 laps through downtown Sandusky, 21.4 km with 42 m of climbing. The organiser's summary box labels it rolling, while its course text promises flat and fast with less than 130 feet of gain. The file sides with the text. The engine reads the whole run as a single flat segment.
Course shape by distance
- Flat 99%
- Climbing 1%
- Descending 1%
The longest stretches
- Bike, climbing0.27 km1% of the bike
- Bike, flat64.5 km70% of the bike
- Run, flat21.4 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, then muscular endurance, on every leg. The demand model scores them 85 and 80 for the swim, the bike and the run alike, with threshold capacity at 70 and the two durability scores at 65 behind them. Because the bike fills 51 percent of a Trained athlete's day, the five largest demands on the whole course are bike demands. The run's aerobic endurance comes sixth.
What the model does not ask for tells you as much. High-intensity capacity reads 43 on the bike and strength and force reads 40, both far below the aerobic pair. There is simply no terrain here that rewards a hard minute. Ask the engine to turn this bike file into a session and it returns two efforts of under a minute each, separated by more than two hours of easy riding. That is an honest portrait of the leg. Two small bumps in a long, level ride.
Now the bands. A Trained athlete swims 38:50, rides 3:00:03 at 182 W and runs 2:01:13, for 5:50:06. The Competitive band finishes in 5:05:51 from 4.15 W/kg at 75 kg and 4:20 /km threshold pace. It gains about 21 minutes on the bike and 18 on the run. None of that comes from a climb, because there is no climb to gain it on. It comes from holding 249 W for more than two and a half hours without a break in the terrain, and then still having legs.
Heat is the variable to watch. The organiser logged highs of 24 C in 2025 and 24 C in 2024, and then 32 C in 2026 with a low of 23 C. The water was 25 C and 24 C in the two years it was measured. For a Trained athlete the run begins close to four hours after the ferry.
- Aerobic endurance85
- Muscular endurance80
- Threshold capacity70
- Aerobic durability65
- Threshold durability65
- Fueling resilience55
- Technical skill55
- High-intensity capacity40
- Anaerobic capacity25
- Strength / force20
- Environmental resilience10
- 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 twelve dimensions on each side of the race. The course side comes from the organiser's route and the event's distances. The athlete side comes from thresholds and connected training history, and every score carries a note on its source and how far it can be trusted. A dimension becomes a gap only where the course asks for more than the athlete can show, and each gap is weighted by the share of the day it covers. Here the bike covers more than half the day, so a bike gap will outrank a swim gap of equal size.
This page knows nothing about you. Its season therefore assumes your gaps sit 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 all three sports. Aerobic durability leads the second, threshold capacity the third and muscular endurance the fourth. The fifth hands the lead back to aerobic endurance. A member's own season is built from their numbers, and it will not match 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 day80 × 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 Ohio 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 aerobic durability
- SupportSwim aerobic durability
- Weeks 6 to 9Foundation 2Closes with a recovery week
- PriorityBike aerobic durability
- PriorityRun aerobic 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 aerobic 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 aerobic 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 aerobic 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
2× course-matched climbs
0.8 min at Zone 5, then 0.8 min at Zone 5, 129 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
- 156 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
- 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 | 0:45:50 | 3:15:26 | 2:25:47 | 6:37:03 |
| Trained1:51 /100m critical swim speed · 3.03 W/kg at 75 kg · 5:06 /km threshold pace | 0:38:50 | 3:00:03 | 2:01:13 | 5:50:06 |
| Competitive1:36 /100m critical swim speed · 4.15 W/kg at 75 kg · 4:20 /km threshold pace | 0:33:35 | 2:39:16 | 1:43:00 | 5:05:51 |
| Elite1:26 /100m critical swim speed · 5.27 W/kg at 75 kg · 3:50 /km threshold pace | 0:30:05 | 2:25:27 | 1:31:07 | 4:36:39 |
Pacing plan
- 0 km0.2%29.8 km/h5:55
- 2.94 km3.3%17.1 km/h0:57
- 3.21 km0%30.8 km/h2:05:41
- 67.7 km3%18 km/h1:13
- 68.1 km-0.3%32.3 km/h0:36
- 68.4 km-4.1%50.3 km/h0:21
- 68.7 km-0.1%31.3 km/h38:15
- 88.7 km-3.7%48.5 km/h0:20
1 more segments in the full plan.
- Run: reach 4:20 /km and this course gives back 44:15.
Where it is decided
Between kilometre 3 and kilometre 68 of the bike.
Once past the first small rise, the road runs level for more than 64 km. The engine gives that one stretch 70 percent of the bike leg, the largest single block of time anywhere on the course. There is no gradient to meter your effort against and nothing to break it up. The group you rode out with sets the tempo, and the tempo feels easy for the first hour.
It is supposed to feel easy. 182 W is what a Trained athlete holds here, and it should feel slightly too comfortable at kilometre 20 and correct at kilometre 60. Riders who instead push to feel busy spend the run in the first half of the bike, and flat terrain hides the bill because the speed stays high. The two short drops in the last 25 km hand back a little time. They do not hand back the legs.
Then the run shows who paid attention. Two laps through downtown Sandusky, dead flat, 2:01:13 at the Trained band's pace. A run this level has no hill to excuse a slowdown. Any fade on the second lap traces straight back to the power you chose on the farm roads.
Getting it wrong
First, the ferry. Jumping off The Carlee Emily into open water is exciting, the self-seeded start puts you among swimmers of your own speed, and people race the first few hundred metres of the bay on adrenaline. The swim is about a ninth of the day. A minute saved in it is not worth a heart rate that stays high for the first half hour of the bike.
The second is believing the word flat means the bike is easy. It means the bike is continuous. On a hilly course you rest on every descent. Here you pedal for three hours with almost no break, and aerobic endurance and muscular endurance lead the demand ranking for exactly that reason. Train long unbroken efforts at race power, not hill repeats.
The third is the 2026 weather. A day that reaches 32 C changes the run, and a runner who starts the second lap through downtown Sandusky at the pace they rehearsed on a cool spring morning will not finish it at that pace. Decide your run pace on race morning, from the temperature, and hold it through the crowds.
Conditions on the day
- 2026high 32 C, low 23 C
- 2025high 24 C, low 17 Cwater 25 C
- 2024high 24 C, low 18 Cwater 24 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 Ohio 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
- 5:50:06
- Of the day on the bike
- 51%
- Dimensions scored per leg
- 12
- Season runway shown
- 24 wk
Questions people ask
- How hilly is the IRONMAN 70.3 Ohio bike course?
- Hardly at all. The organiser puts the one-loop 90 km course at approximately 820 feet of gain and calls it flat, and the file measures 180 m. The steepest sustained rise is 269 m at 3.3 percent, and 99 percent of the whole course reads as flat.
- How does the ferry start at IRONMAN 70.3 Ohio work?
- Athletes walk about 150 yards from transition at Paper District Marina to the Kelleys Island Ferry beside Jackson Street Pier. The ramp is lowered to the water and you jump off feet first in a rolling, self-seeded start, then swim one loop of Sandusky Bay back to the marina.
- What water temperature should I expect in Sandusky Bay?
- The organiser logged 25 C in 2025 and 24 C in 2024 and has no reading for 2026. The wetsuit rule is not on the course page, so check the athlete guide in race week.
- 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 24 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, and 5150 is a trademark, 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.