A productive Half Ironman brick workout is usually a controlled bike ride followed immediately by a short run. Start with 60–90 minutes cycling plus 10–15 minutes easy running; build towards one race-specific session of roughly 2.5–3 hours riding and 20–40 minutes running during the final 4–8 weeks. The purpose is to practise pacing, T2 and nutrition—not to complete an entire 70.3 in training.
A Half Ironman brick workout links cycling to running, two disciplines that rarely feel the same when performed back-to-back as they do separately. The first kilometres off the bike can feel awkward, your perception of pace can be misleading, and small bike-pacing or fueling mistakes often become obvious on the run. The solution is not simply training harder: it is learning to execute the transition under increasingly realistic conditions.
This guide provides five practical 70.3 brick workouts, a 12-week progression, intensity guidance and a race-rehearsal checklist. If you are new to the concept, first read our introduction to triathlon brick workouts. The workout prescriptions here are adaptable coaching examples, not a one-size-fits-all protocol established by a clinical trial.
What is a Half Ironman brick workout?
A brick is two workouts performed consecutively, usually a bike followed by a run with only enough time in between to change shoes and organise equipment. For a Half Ironman (70.3), it lets you practise running after sustained cycling fatigue, transitioning efficiently and controlling effort during the early part of a 21.1 km run.
Brick workouts are useful for race specificity, but their physiological benefits should not be exaggerated. A 2022 systematic review found that running performance often suffers after cycling, while evidence about the precise biomechanical causes and the ideal bike cadence or intensity strategy was mixed. One small six-week experimental study found improvements during the cycle-to-run transition, but not a greater improvement in overall cycle-run performance than conventional training. A brick is a useful tool—not a replacement for building running fitness separately.
How long and how often should you brick for 70.3?
For many age-group athletes, one bike-to-run session in a normal race-specific training week is sufficient. Early in the build, that may be a short 10-minute run after an easy ride every one or two weeks. Later, you can use one purposeful brick most weeks and reserve demanding race rehearsals for occasional key weekends.
| Time before race | Bike session | Run off the bike | Priority |
|---|---|---|---|
| 12+ weeks | 60–90 min, easy endurance | 10–15 min easy | Transition habit and relaxed rhythm |
| 8–12 weeks | 75–120 min with controlled race effort | 15–25 min | Bike pacing and measured run start |
| 4–8 weeks | 2–3 h, substantial race-specific work | 20–40 min | Fueling, pacing and early-run durability |
| 2–4 weeks | Final key rehearsal, based on fatigue | 20–35 min | Confirm setup without overreaching |
| Race week | Short easy spin, a few pickups | 5–10 min easy | Fresh legs, familiar transition |
These are illustrative ranges, not compulsory milestones. If adding a brick makes your standalone long run or next interval session noticeably worse, the total training load is probably too high. A run of 10–20 minutes is enough for frequent transition practice; 20–45 minutes is often plenty for your key race-specific sessions. You do not need to run a full half marathon after a 90 km ride before race day.
5 Half Ironman brick workouts to use in training
These five sessions progress from low-fatigue coordination to realistic 70.3 execution. Select the one that matches your current fitness and training phase rather than attempting every workout in the same week.
1. The beginner transition brick
Best for: new triathletes and early base training.
- Bike: 60–90 minutes at conversational endurance intensity.
- T2: Change shoes and start running without a prolonged rest.
- Run: 10–15 minutes easy. Keep the first five minutes particularly relaxed.
- Focus: Smooth transitions, comfortable cadence and learning what the first steps off the bike feel like.
This session should be easy enough that you could still complete the rest of your training week. Resist the temptation to turn the short run into a fitness test just because your legs feel surprisingly quick at the start.
2. The 70.3 pace-control brick
Best for: athletes starting race-specific work, approximately 8–12 weeks out.
- Bike: 90 minutes total with 3 × 10 minutes at your planned Half Ironman bike effort, separated by five easy minutes.
- T2: Make a normal race-style transition.
- Run: 20 minutes. Begin 10 minutes easy, then approach your sustainable 70.3 run effort without sprinting.
- Focus: Learn how sustainable cycling feels before attempting race-pace running.
If you train with power, use your individually planned 70.3 power rather than copying another athlete's percentage of FTP. A controlled heart-rate or RPE target also works. For more context, see our Half Ironman bike pacing strategy.
3. Long aerobic ride, short run
Best for: building fatigue resistance without sacrificing a separate long run.
- Bike: 2–3 hours primarily in your normal endurance zone; the final 30–45 minutes can use controlled race-specific effort if appropriate.
- Run: 15–30 minutes, mostly easy and rhythm-focused.
- Focus: Keep your stride under control after a substantial bike session.
The training benefit comes from practising restraint: you should finish knowing that you could have continued at a measured effort. Save your hardest run for a planned quality session on another day rather than stacking maximal stress on the same weekend.
4. The key Half Ironman race-rehearsal brick
Best for: experienced and adequately prepared athletes, generally around 4–8 weeks before race day.
- Bike: 2.5–3.5 hours including substantial stretches at the power, position and nutrition schedule planned for race day.
- T2: Use the same shoes, hydration setup and routine you intend to race with.
- Run: 30–45 minutes. First 10 minutes deliberately conservative; settle towards sustainable 70.3 effort only when it feels under control.
- Focus: Test the entire system—bike pacing, stomach comfort, shoe change and run control.
Assess the session based on the quality of your decisions, not whether you can finish with a sprint. If you start the run far above race effort because it initially feels easy, the workout may teach the wrong pacing habit. For some athletes, reducing the run to 20–30 minutes will make the rehearsal more productive.
Race-rehearsal rule: You are trying to confirm that your plan works after several hours of cycling—not prove you can complete all 70.3 miles before the event.
5. The low-fatigue taper brick
Best for: keeping transitions familiar during race week.
- Bike: 30–50 minutes mostly easy, with several brief controlled race-effort pickups.
- Run: 5–10 minutes easy with a few relaxed strides only if they are already part of your normal routine.
- Focus: Confidence and rhythm without creating fatigue.
A taper brick is not the moment to discover new training zones, test a new pair of shoes or practise a heroic interval. If travel or recovery makes the session impractical, skipping it is better than arriving at the start line fatigued.
A practical 12-week Half Ironman brick progression
A gradual progression is more reliable than constantly increasing both bike and run distance. The example below assumes you already tolerate regular bike and run training; beginners can shorten each workout and take more recovery weeks.
| Weeks to race | Suggested focus | Run after bike |
|---|---|---|
| 12–10 | Easy transition after a standard endurance ride, every 1–2 weeks | 10–15 min |
| 9–7 | Controlled 70.3 bike effort and relaxed running, most weeks | 15–25 min |
| 6–5 | One substantial race-specific brick, other sessions lighter | 20–40 min |
| 4–3 | Final specific rehearsal based on your recovery | 20–35 min |
| 2 | Shortened volume, familiar bike-to-run rhythm | 10–20 min |
| Race week | Optional brief taper brick | 5–10 min |
This is not a standalone plan. Your swimming, long run, key bike sessions, easier days and recovery weeks still have to fit around the bricks. See our free 20-week Half Ironman training plan for a broader progression.
How hard should the bike and run be?
On the bike: most bricks do not need high intensity. Use easy aerobic riding for short transition sessions and your individually estimated 70.3 effort for race-specific blocks. Avoid accumulating big surges late in the ride simply to force the run to feel harder. FTP-based targets may be useful, but actual race power depends on expected finish time, heat, course demands and your current cycling durability.
On the run: the first minutes should feel deliberately restrained. Start by finding your posture and breathing, then use sustainable pace or effort—not instant GPS speed—to settle in. USA Triathlon emphasises controlling early-run pace and rehearsing the transition rather than forcing maximum intensity. Read USA Triathlon's transition guidance.
For structured intensity ranges, see Triathlon Training Zones Explained and our Cycling Power Zones resource.
Fuel the brick like a Half Ironman rehearsal
Longer bricks are an ideal opportunity to test the nutrition you intend to use on the bike and immediately after T2. For a race-specific session, practise the timing, products, drink concentration and amounts you are already tolerating in training. Many experienced endurance athletes work towards approximately 60–90 g of carbohydrate per hour on long efforts, but this is not a mandatory target for every athlete. Fluid and sodium needs also vary with conditions and sweat losses.
If you repeatedly experience stomach distress on the run, look back at how much you consumed, what and when you drank, bike intensity and weather—rather than simply avoiding all fuel. Build tolerance progressively. Our Half Ironman nutrition plan and gut-training guide provide more detail.
Five brick-workout mistakes to avoid
- Running too fast off the bike. Easy early kilometres are often more useful than proving you can hit a standalone 5K pace.
- Adding too much run volume. A 45-minute brick run on top of another long run can create a large recovery cost.
- Ignoring the bike intensity. If a brick run goes badly, an overpowered ride may be the explanation.
- Not rehearsing nutrition. Race-day products should not be a surprise after two hours of cycling.
- Treating every brick like a race. Most transition practice should be repeatable, not maximal.
One useful test is to ask what you learnt from each brick. If the answer is simply “I was exhausted,” reduce the session until it teaches something actionable.
Half Ironman brick workout FAQ
How many brick workouts should I do per week for a 70.3?
For many age-groupers, one purposeful brick in race-specific weeks is adequate. Early in training, a short brick every one or two weeks may be enough. Two can work if one is very short and easy, but two demanding bricks are not necessary for most people.
How long should my Half Ironman brick run be?
Frequent transition runs can be 10–20 minutes. Key race-specific sessions can use roughly 20–45 minutes depending on experience, fatigue and the purpose of the workout. Full half-marathon runs immediately after long bike sessions are not required.
Should I run at goal Half Ironman pace off the bike?
Start below goal effort to let your breathing and stride settle. In a specific rehearsal, you may gradually approach a realistic 70.3 effort if the bike and nutrition were controlled. Do not force pace numbers when conditions or fatigue indicate otherwise.
When should I do my last big brick before a 70.3?
Many athletes plan a final substantial rehearsal around 3–4 weeks before their event; the exact timing depends on training history and recovery. Reduce overall load during the taper and avoid introducing new hard sessions.
Do I need to ride 90 km and then run 21.1 km before race day?
No. Most of the value comes from learning the bike-to-run transition, pacing and fueling under manageable fatigue. The full-distance combination may cost too much recovery without offering proportionate benefit for most age-group athletes.
Is a brick workout the same as a race rehearsal?
Not necessarily. Every back-to-back bike-run session is a brick, but only selected key sessions need to approximate 70.3 bike effort, use race equipment and replicate your nutrition and transition routine.
The bottom line
The best Half Ironman brick workout is the one that matches your training phase. Use short, easy transitions to make running off the bike familiar, then introduce controlled race-specific bricks to test bike pacing, fueling and the first kilometres of the run. Avoid turning every weekend into an unofficial Half Ironman.
Turn five workouts into a complete season.
Combine bricks with a progressive swim, bike and run schedule—and enough recovery to absorb your work.
Read the complete Half Ironman training guide · Explore the free 20-week plan
Updated October 2026. This article combines published exercise-science findings and guidance from established triathlon organisations with TriathlonLoop's illustrative training-session examples. The specific workout durations are not universally validated prescriptions and should be adapted to individual preparation.
- Bini and colleagues (2022): systematic review of the physiological and biomechanical effects of running after cycling.
- Hue and colleagues (2002): six-week experimental study of multicycle-run transition training.
- USA Triathlon: How to Use Brick Workouts in Triathlon Training.
- TrainingPeaks: Using Brick Workouts in Triathlon Training.
