For most Half Ironman athletes, the best brick-workout strategy is to use short bike-to-run sessions regularly and save the biggest race-specific bricks for the final six to eight weeks before the race. A useful key session might be a 2.5–3 hour ride with controlled 70.3-specific work followed by 20–40 minutes of running that begins easier than goal race effort. You do not need to ride 90 km and then run a full half marathon in training to prepare for a 70.3.
A Half Ironman brick workout should answer a race-day question. Can you control the bike well enough to run? Does your fueling still feel comfortable in T2? Can you settle into the first kilometres without chasing pace? Those questions matter more than simply making the session as long or as hard as possible.
This guide is deliberately more specific than our general Triathlon Brick Workouts 101 article. It focuses on the 70.3 distance: how often to use bricks, how long the run should be, which sessions fit different phases of the build, and how to progress toward a race rehearsal without turning training into a second race.
The exact sessions below are practical Triathlon Loop programming examples rather than a clinically validated formula. Research supports the value of practising the cycle-to-run transition, but it does not identify one universal brick duration, cadence or bike-intensity prescription that is best for every athlete. Your current fitness, run durability, weekly load and recovery capacity should decide how aggressively you progress.
What is the best Half Ironman brick workout?
There is no single best Half Ironman brick workout for every point in a training plan. Early in the build, the most useful session may be a normal endurance ride followed by ten easy minutes of running. Later, a race-specific brick can combine sustained 70.3 bike effort, your planned nutrition and a controlled run long enough to expose pacing mistakes.
The progression matters because a brick creates training stress in two disciplines at once. A huge session performed too early may leave you too fatigued to complete the following long run, bike intervals or swim sessions. A smaller session that you can repeat and absorb may produce more useful preparation over several weeks.
| Training stage | Typical brick | Run off the bike | Main purpose |
|---|---|---|---|
| 12+ weeks out | Easy or steady bike | 10–15 min easy | Make the transition familiar with little extra fatigue |
| 8–12 weeks out | Bike with controlled race-effort blocks | 15–25 min controlled | Connect pacing and transition technique |
| 4–8 weeks out | Long ride with substantial 70.3-specific work | 20–40 min, progressive | Rehearse race power, fueling and early-run control |
| 2–4 weeks out | Final key race rehearsal | 20–35 min controlled | Confirm decisions without creating race-level fatigue |
| Race week | Short easy ride with a few race-effort touches | 5–10 min easy | Keep the transition familiar while staying fresh |
These ranges are not targets you must hit. An athlete with a strong cycling background but limited running durability may keep the runs shorter. A durable runner who recovers well may occasionally extend the run, but the extra distance should have a clear purpose rather than being added for confidence alone.
How often should you do brick workouts for a Half Ironman?
For many age-group athletes, one purposeful brick in most race-specific weeks is enough. In the early base phase, a brick every one or two weeks may be sufficient. During the final eight to ten weeks, a short run can follow selected bike sessions more regularly, while the larger race-rehearsal bricks remain selective.
Some training plans use two bricks in a week: for example, a ten-minute easy transition run after a midweek bike plus a longer weekend brick. That can work when the first session is genuinely low cost. It is very different from performing two long, race-pace bricks every week.
Your weekly structure should decide the frequency. If a brick causes the next quality run or long run to deteriorate, the combined load is probably too high. The purpose of Half Ironman training is not to become excellent at recovering from brick workouts; it is to arrive on race day with enough cycling durability and running fitness to execute the entire 70.3.
How long should a Half Ironman brick run be?
The run does not need to be long to create a specific bike-to-run stimulus. The first minutes are where you experience the largest practical transition problem: posture changes, pace perception is distorted, the legs already carry cycling fatigue and your planned run effort can feel unusually slow or fast.
That is why 10–20 minutes is enough for many regular transition bricks. These short runs let you practise getting off the bike, finding a relaxed stride and controlling the opening pace without turning every ride into a major combined session.
For key Half Ironman-specific workouts, a run of roughly 20–45 minutes often provides enough time to test whether the bike effort and fueling strategy carry into sustainable running. Longer runs can be used occasionally by experienced athletes, but they create a much larger recovery cost. There is no requirement to run 21.1 km after a long bike in training.
If your main goal is learning the mechanics and pacing of the first kilometres, use our separate guide to running after cycling. The rest of this article is about programming the entire 70.3 brick session.
5 Half Ironman brick workouts to use during your 70.3 build
The five sessions below form a progression rather than a checklist. You do not need to complete all five in every build, and you should not increase bike duration, bike intensity and run duration at the same time simply because race day is getting closer.
1. Short transition brick — low fatigue, high frequency
Best used: throughout the build, especially 12+ weeks before race day.
Session: ride 60–90 minutes at easy aerobic intensity. Transition normally and run for 10–15 minutes at an easy conversational effort. Keep the first five minutes deliberately calm and finish with the feeling that you could comfortably continue.
This is the most repeatable brick in the plan. It is useful when the goal is simply to make T2 and the first minutes of running routine. Because the run is short and easy, it can often be added after an ordinary bike without becoming a second key workout.
2. Race-effort control brick — learn what sustainable feels like
Best used: around 8–12 weeks before race day.
Session: ride 90–120 minutes total. After warming up, complete 3 × 15 minutes at your planned Half Ironman bike effort with 5 minutes easy between blocks. Finish with 10 minutes easy, transition, then run 15–25 minutes. Keep the first 5–10 minutes easy before settling toward planned 70.3 run effort if the session remains controlled.
The purpose is not to prove that you can run fast after cycling. It is to learn whether your chosen bike intensity leaves your breathing and legs sufficiently controlled to establish the run you actually want on race day.
3. Long ride + short run — build durability without sacrificing the long run
Best used: during the middle and later build, roughly 6–10 weeks out.
Session: complete a 2.5–3.5 hour endurance ride. Keep most of the ride easy to steady and include 45–75 minutes total at planned 70.3 effort in manageable blocks. Practise your intended race nutrition. Transition into 15–25 minutes of easy running.
This session is especially useful when you still need a separate long run elsewhere in the week. The bike provides the main endurance load, while the short run confirms that pacing, position and fueling have not left you unable to run smoothly.
4. 70.3 race-rehearsal brick — test the complete system
Best used: approximately 4–8 weeks before the race, with one final substantial rehearsal commonly completed before the taper begins.
Session: ride 2.5–3 hours using the bike, position, bottles and nutrition strategy you expect to race with. After an easy opening, accumulate 75–120 minutes at planned 70.3 effort without turning the ride into a time trial. Transition efficiently and run 25–40 minutes. Start below goal race effort, then settle toward planned 70.3 effort only if breathing, stomach and mechanics remain stable.
This is the most important brick for many athletes because it tests several decisions at once: bike pacing, aerodynamic comfort, fueling, transition setup and early-run restraint. Record what happened rather than grading the workout only by average speed or run pace.
A race rehearsal should reduce uncertainty. If you need several days to recover because you raced the bike and then forced a long hard run, the session may have been more exhausting than informative.
5. Taper brick — keep the feeling without carrying fatigue
Best used: in the final 7–10 days when it fits your taper and recovery pattern.
Session: ride 35–50 minutes easily with 2–4 short blocks of 2–4 minutes near race effort. Transition into 5–10 minutes of relaxed running with a few brief controlled pickups if you normally use them.
This session is not a final fitness test. Its job is to keep the transition familiar while training volume is falling. If you finish wondering whether you should have done more, that is usually preferable to carrying deep fatigue into race week.
Half Ironman brick workout progression: 12 weeks to race day
A good progression increases specificity more reliably than it increases suffering. Early bricks can be short and easy. As race day approaches, selected sessions become longer and include more race-specific bike work, race nutrition and controlled running. The taper then removes volume again.
| Time to race | Brick emphasis | Example | What to learn |
|---|---|---|---|
| 10–12 weeks | Transition familiarity | 75 min easy bike + 10–15 min easy run | Settle the stride without chasing pace |
| 8–10 weeks | Race-effort control | 90–120 min bike with race blocks + 15–25 min run | Check whether bike effort protects the run |
| 6–8 weeks | Durability + fueling | 2.5–3 h bike + 15–30 min run | Test products, position and late-bike control |
| 4–6 weeks | Race rehearsal | 2.5–3 h specific bike + 25–40 min controlled run | Rehearse the full execution system |
| 2–4 weeks | Final confirmation | Moderate-duration brick, no maximal test | Confirm decisions and begin reducing fatigue |
| Race week | Familiarity | 35–50 min bike + 5–10 min run | Stay sharp and fresh |
If you are following a complete schedule, use this progression alongside the 20-week Half Ironman training plan. The brick should fit the rest of the week rather than becoming an additional workout placed on top of an already full programme.
How hard should the bike be in a 70.3 brick workout?
The bike intensity should match the purpose of the session. An adaptation brick can be easy. A race-specific brick should include enough work near planned 70.3 intensity to test whether that intensity is sustainable when followed by running. It does not need to contain repeated threshold surges simply to make the run feel harder.
Use the Half Ironman bike pacing strategy to choose a duration-based IF and watt target for this rehearsal, then judge the target by the quality of the run that follows.
Research on the cycle-to-run transition is more nuanced than many training articles suggest. A 2022 systematic review found conflicting results when studies manipulated cycling cadence and intensity before running. That means there is not enough evidence to claim that one specific cadence or end-of-bike trick reliably improves the run for every triathlete.
There is stronger practical reason to monitor the total cost of the bike. In one study of triathletes, higher perceived exertion during cycling was associated with a greater impairment in subsequent running economy. Another field study found slower running after a highly variable one-hour cycling protocol than after constant cycling at the same mean power, although other experimental protocols have produced different results. The useful takeaway is not “never vary power”; real courses make that impossible. It is to avoid unnecessary surges and judge race effort by how well it supports the run.
Use power, heart rate and RPE together rather than forcing a single metric. Our triathlon training zones guide explains how to combine those signals, while the cycling power zones guide covers bike-specific intensity.
How fast should you run off the bike?
Most Half Ironman brick runs should begin easier than the pace you hope to average on race day. The first minutes are poor territory for proving fitness: pace perception is altered, the legs are changing movement pattern and the physiological cost of running can be higher after cycling.
For a short transition brick, keep the entire run easy. For a race-specific session, let the first five to ten minutes settle before moving toward planned 70.3 effort. In a major rehearsal, the strongest outcome is often an even, controlled run that confirms the bike was sustainable—not a spectacular first kilometre followed by rapidly increasing effort.
A small randomized trial found that six weeks of repeated cycle-run training did not improve overall cycle-run performance more than normal training, but it did improve performance around the transition and first 333 metres. That supports practising the transition itself without implying that every brick needs a long or hard run.
Use Half Ironman brick workouts to rehearse fueling
For a 70.3 athlete, one of the best reasons to perform a longer brick is nutrition. The bike is normally where most race carbohydrate and fluid will be consumed, while the run reveals whether that intake remains tolerable once impact and body temperature increase.
Use important bricks to rehearse the actual system: breakfast timing when appropriate, bottle concentration, carbohydrate per hour, aid-station substitutes, caffeine timing, final bike intake and what you plan to take during the opening part of the run. Do not change several variables at once if something goes wrong.
Our Half Ironman nutrition plan covers the race-specific numbers and logistics in detail. If you need to build tolerance to a higher carbohydrate intake, use the gut-training guide before relying on that intake in a key rehearsal.
Where should a Half Ironman brick workout go in your week?
The largest brick usually belongs where you already place the long bike, often on a weekend. That avoids creating another separate high-load day. A short ten-minute transition run can also follow a midweek bike when it does not compromise the next key session.
Protect the standalone long run. A common mistake is to make the brick run so long that the athlete either skips the long run or completes it with poor mechanics and excessive fatigue. For many age-groupers, a long ride plus short-to-moderate brick on one day and a separate easy long run on another day creates a better balance of specificity and running development.
After a large race-specific brick, schedule easy training or rest according to your normal recovery pattern. Avoid placing the session immediately before your hardest run intervals simply because that is where it fits on paper.
Do you need a full 70.3 race simulation in training?
No. You do not need to swim 1.9 km, ride 90 km and then run 21.1 km at race effort before race day. A full-distance simulation creates a large recovery cost while offering limited additional information once you have already tested each part of the race system in well-designed training.
A scaled rehearsal can answer the important questions with less damage: can you sustain your planned bike effort in race position, consume the planned nutrition, transition efficiently and run for 25–40 minutes at controlled 70.3 effort? Combine that information with a separate long run and long ride, and you can build confidence without racing the event in training.
That approach also leaves room for the training that actually builds fitness. If you are uncertain how the brick fits into the wider programme, start with our complete Half Ironman training guide.
Common Half Ironman brick workout mistakes
Making every brick race-specific. Short, easy transition runs are useful precisely because they are cheap enough to repeat. Save the demanding combinations for the part of the build where they answer race-specific questions.
Running goal half-marathon pace regardless of the bike. A 70.3 run starts after 90 km of cycling. Your sustainable triathlon run effort may differ from standalone half-marathon pace, especially in heat or on a difficult course.
Adding duration for confidence. If 30 minutes of running has already shown that your bike pacing and fueling work, adding another hour may create fatigue without revealing much more.
Ignoring fueling during training bricks. A good run after an underfueled two-hour ride does not prove that your planned four-to-seven-hour race strategy will work. Longer bricks should increasingly reproduce the nutrition system you intend to race.
Judging the workout by speed alone. Look at RPE, power stability, heart-rate response, stomach comfort, transition execution and whether the run settles as planned. A slightly slower session that validates the complete system can be more useful than a training personal best.
Half Ironman brick workout FAQ
How often should I do brick workouts for a Half Ironman?
One purposeful brick in most race-specific weeks is enough for many age-group athletes. Early in the build, every one or two weeks may be sufficient. A second weekly brick can be a very short, easy transition run when recovery remains good.
How long should a Half Ironman brick run be?
Regular transition bricks can be only 10–20 minutes. Key race-specific sessions often use roughly 20–45 minutes of running. Longer runs are optional and should be justified by the athlete's durability and recovery capacity rather than treated as a requirement.
What is a good 70.3 brick workout 4–8 weeks before the race?
A useful race-specific option is a 2.5–3 hour bike with substantial controlled work near planned 70.3 effort, followed by 25–40 minutes of running. Start the run easier than goal effort and rehearse your race nutrition and equipment.
When should I do my last big Half Ironman brick workout?
Many athletes place the final major race rehearsal roughly two to four weeks before race day, depending on the size of the session and how quickly they recover. The final week should contain only a short, low-fatigue transition session if one is used at all.
Should I run 13.1 miles after a long bike before my Half Ironman?
No. Running a full half marathon after a long bike is not required. A shorter controlled run can test bike pacing, fueling and transition execution while preserving recovery for the rest of the training plan.
Should a Half Ironman brick run be at race pace?
Not always. Easy bricks should stay easy. During race-specific sessions, begin the run conservatively and include planned 70.3 effort only after your stride and breathing settle. The entire run does not need to be at race pace.
Is a brick workout the same as a race rehearsal?
No. Every bike-to-run session is a brick, but only selected bricks need to reproduce race equipment, nutrition and substantial race-specific intensity. Most bricks can be much shorter and simpler.
Final takeaway
The best Half Ironman brick workout is not the one that leaves you most exhausted. It is the session that answers the question appropriate to your training phase. Early bricks teach the transition. Mid-build bricks connect bike effort to running. Later rehearsals validate pacing, position and fueling. Taper bricks preserve familiarity without adding fatigue.
Build specificity gradually, keep the majority of transition runs shorter than your standalone run sessions and judge every major brick by what it tells you about race execution. When a session confirms that you can ride within yourself, fuel consistently and begin the run under control, it has done its job.
Use bricks to practise the connection between cycling and running—not to prove that you can complete the whole race before race day.
Follow a structured Half Ironman progression
If you want the long rides, brick sessions, run progression and recovery weeks already organised, use our beginner Half-Distance Triathlon Training Plan.
This guide separates research-supported principles from Triathlon Loop's practical programming examples. Current evidence on running after cycling was checked against the 2022 systematic review of the cycle-to-run transition. Evidence on specific cycle-run practice was informed by a randomized six-week multicycle-run training study. Bike-execution context was checked against research on cycling power variability and subsequent running and cycling RPE and subsequent running economy. Because cadence and intensity findings are conflicting across protocols, the workout durations and progressions on this page are presented as practical coaching frameworks rather than universal evidence-based prescriptions.
Inline photography: RUN 4 FFWPU via Pexels. Featured image: Brandic Digital via Pexels.
