1.9km swim · 90km bike · 21.1km run
Sunday, September 13, 2026 · Ada Ciganlija, Belgrade
Swim in Sava Lake → two flat bike loops through the city → run around the lake
Prep time: 5 weeks (again) · Target: sub-6:00
Longest swim: 1300m · Rides on record: one · Marathons this year: one, 4:14
Live from Strava, synced every 30 minutes. Swim ■ Bike ■ Run ■
You have never swum 1900m. Longest: 1300m at ~2:45/100m — a pace that extrapolates to a ~52min race swim, comfortably inside the cutoff. But 1300m fresh in a quiet lake is not 1900m in a wetsuit with 1000 other people, and the swim is the one discipline you can't grit through — deep-water fatigue is a safety problem, not a suffering problem. The plan still hangs on one rule: swim 3× per week, every week, no exceptions. Everything else can flex.
Swim fitness builds fastest of the three — it's technique- and frequency-limited, and the engine behind it (yours) is already marathon-sized. 1300m → 1900m in 4 weeks at 3 swims/week is a short, well-trodden path. Wetsuit legal at 23°C = free buoyancy worth 5–10s/100m. Breaststroke is legal.
| Segment | Cutoff | Realistic pace | Time | Margin |
|---|---|---|---|---|
| Swim 1.9km | 1:10 from start | 2:30–2:50/100m, breaststroke mix | 48–54 min | ~18 min |
| T1 | — | unhurried | 6 min | — |
| Bike 90km | 5:30 race clock | 25–27 km/h flat | 3:20–3:36 | ~50+ min |
| T2 | — | unhurried | 5 min | — |
| Run 21.1km | 8:30 race clock | 6:00–6:20/km (5:50 fresh) | 2:07–2:14 | 1h+ |
| Total | 8:30 | ≈ 6:30–6:55 |
A-goal: sub-6:00. The budget: swim 48–52 + T1 ≤4 + bike 3:00–3:10 (29–30km/h) + T2 ≤3 + run 1:58–2:05 (5:35–5:55/km) = 5:53–6:14. Sub-6 lives or dies on the bike — your 25km/h first-ever ride is a floor, not a ceiling, and the course is flat and closed. B-goal: sub-6:30 (fallback pacing lands ~6:25). C-goal: finish — even a disaster swim + slow bike leaves 3+ hours for the run.
Decision point — September 5: 1900m continuous in Ada (any stroke mix) at the Week 4 rehearsal. Pass → taper and race. Fail → one retry Sep 8, then an honest conversation. Never swim open water alone: lifeguarded zone or buddy + swim buoy, every time.
Closed, protected, flat water. No current, no waves, no salt. ~23°C in September → wetsuit legal. Rolling start: seed yourself at the back, cross the mat, your personal 1:10 clock starts. Clean water beats the washing machine.
Wide city avenues through the Ada bridge area. Fast, closed roads, no real climbing — wind on exposed river sections is the only terrain. Draft-illegal: 12m gap, pass within 25s.
Flat circuit around Sava Lake — the paths you already run every week. Shaded wooded sections, aid stations every lap. You will know every meter of this course.
14–27°C. Race morning ~15–18°C, warming through the run. Exposed lake sections in afternoon sun: cap + sunscreen. Historically ideal racing weather.
Philosophy: swim frequency over everything (14 swims to race day). Long rides grow 40→85km with eating practice. The run is maintained, not built. Brick runs every weekend. Sessions marked ★ are never skipped; everything else flexes.
| Week | Dates | Swim | Bike | Run | Key Sessions |
|---|---|---|---|---|---|
| 1 | Aug 8–16 | 2.5km (3×) | ~100km | ~20km | 400m continuous test · 50km ride |
| 2 | Aug 17–23 | 3.5km (3×) | ~130km | ~25km | ★ First open water at Ada · 60km + first brick |
| 3 | Aug 24–30 | 5km (3×) | ~150km | ~28km | ★ 1200m OW · 75km + brick · 16km run |
| 4 | Aug 31–Sep 6 | 5km (3×) | ~160km | ~30km | ★★ 1900m REHEARSAL + race simulation |
| 5 | Sep 7–13 | 1.5km | ~60km | ~12km | Taper → RACE DAY |
Nine days, so it breathes. You already opened it with a 40km ride + 2.5km run — that was your first brick, whether you meant it or not.
| Day | Session | Details |
|---|---|---|
| Sat 8 | ✅ Ride 40km + 2.5km run | Done. Already training. |
| Sun 9 | Swim #1 ★ | Pool. 8×50m, 20–30s rest. Relaxed exhale underwater, long strokes. Rhythm, not fitness. |
| Mon 10 | Rest | Buy gear. Register. Book bike service. |
| Tue 11 | Bike 60–75min | ~25km flat. Practice drinking while riding, shifting early. |
| Wed 12 | Swim #2 ★ | 6×100m, 30–45s rest. Find the pace you could hold all day. |
| Thu 13 | Run 10km easy | Your normal run, 5:50–6:10/km. |
| Fri 14 | Rest | Or 30min easy spin. |
| Sat 15 | Long ride 50km ★ | Flat. Eat at 45min and 1h30. Bottle every 15min. This is nutrition training. |
| Sun 16 | Swim #3 ★ + 5km run | 800m continuous test (breaststroke breaks OK, don't hold the wall) + 4×50 easy. After July's 1300m this should be comfortable. |
Checkpoint: 400m without holding the wall = on schedule. If not → book 1–2 swim lessons THIS WEEK. A coach fixing your breathing is worth more than any session in this plan.
| Day | Session | Details |
|---|---|---|
| Mon 17 | Rest | |
| Tue 18 | Swim #4 ★ | 5×200m, 45s rest. Steady, boring, controlled. |
| Wed 19 | Bike 90min | ~35km with 3×10min at race effort (can barely talk). |
| Thu 20 | Run 10km + strides | |
| Fri 21 | Swim #5 — OPEN WATER ★★ | Ada, 20–30min, lifeguarded zone or buddy + buoy. Wetsuit on/off, sighting every ~10 strokes, staying calm over dark water. Scariest session of the plan — everything after it is easier. |
| Sat 22 | 60km + BRICK 3km ★ | Eat 60g carbs/hour riding. Then run 3km immediately on alien legs. |
| Sun 23 | Long run 14km | Ada loop. Familiar territory. |
| Day | Session | Details |
|---|---|---|
| Mon 24 | Rest | |
| Tue 25 | Swim #7 ★ | 3×400m, 60s rest. The week distance stops being scary. |
| Wed 26 | Bike 90min | ~35km, 2×15min race effort. |
| Thu 27 | Run 10km easy | |
| Fri 28 | Swim #8 — 1200m OW ★★ | Continuous in Ada, wetsuit. Landmark to landmark. Breaststroke to recover, just keep moving. |
| Sat 29 | 75km + BRICK 5km ★ | Longest ride of your life, with 2×20min at 29–30km/h race effort. Bottle+gel rhythm. Then 5km at 6:00/km. |
| Sun 30 | Long run 16km | Or rest if wrecked — the ★ sessions are banked. |
~9.5 hours. The hardest training week. Survive it and you're basically ready.
| Day | Session | Details |
|---|---|---|
| Mon 31 | Rest | |
| Tue 1 | Swim #10 | 1000m relaxed: 400+300+200+100. |
| Wed 2 | Bike 90min | ~35km easy-moderate. |
| Thu 3 | Run 10km, 5 at race pace | Groove 5:45/km on fresh legs. |
| Fri 4 | Rest | Sleep. Tomorrow is the whole plan in one day. |
| Sat 5 | ★★★ THE REHEARSAL | 1900m OW swim → 60km ride @ 29km/h+ → 5km run @ 5:45. Full dress rehearsal at Ada: wetsuit, race nutrition, transitions from a backpack, race-day wake-up time. Gate #1: the swim (can you race at all). Gate #2: the bike (sub-6 plan or 6:15 plan). Finish it and know, not hope. |
| Sun 6 | 14km very easy or rest | Only if the body says yes. |
DECISION POINT (Sep 5): 1900m continuous, any stroke mix, no stopping → you will finish this race. Not yet → retry Sep 8, then honest talk. Based on the Week 1–3 progression: you'll pass.
| Day | Session | Details |
|---|---|---|
| Mon 7 | Rest | |
| Tue 8 | Swim 800m easy | Relaxed. You're a swimmer now. |
| Wed 9 | Bike 45min + final check | Shifting, brakes, tires. Anything off → shop TODAY. |
| Thu 10 | Run 6km + strides | |
| Fri 11 | Swim 400m at Ada + check-in | Athlete check-in, race briefing, study transition. |
| Sat 12 | Bike check-in | Rack the bike (mandatory). Lay out both transitions. Carb-load 8–10g/kg. Early bed. |
| Sun 13 | RACE DAY | IRONMAN 70.3 BELGRADE — 1.9 / 90 / 21.1 |
Open water + no wall + dark bottom = adrenaline = short breath = "drowning" feeling while your muscles are fine. Fix: exhale fully underwater, and exposure — hence 4+ open-water sessions before race day.
Gliding beats thrashing. A relaxed 2:45/100m swimmer beats a 2:15 swimmer who blows up at 800m. Your race pace should feel embarrassingly easy.
Every 8–10 strokes: eyes up like a crocodile, find the buoy, head down. Practice from Week 2 or you'll swim 2200m on race day.
So is backstroke, so is treading water to reset. Illegal: making progress holding a kayak, or walking on the bottom. "Freestyle until bored, breaststroke to breathe, repeat" finishes thousands of 70.3 swims every year.
Legs float, body warm, buoyant even at rest. Swim in it 3+ times before race day — it changes your stroke. Body Glide on the neck.
Two swim lessons in Week 1. A coach watching your breathing for 45 minutes saves more time than every other session combined.
Projected finish: 5:53–6:14 — sub-6 when the swim and bike land on the good end. The Sep 5 rehearsal picks the plan; fallback pacing (27km/h, 6:00/km) still lands ~6:25. Anything under 8:30 gets the same medal and the same sentence: you are an IRONMAN 70.3 finisher.
| When | What |
|---|---|
| 3h before | Toast + jam, banana, coffee, 500ml water. Stop eating 90min out. |
| 15min pre-swim | 1 gel + sips of water |
| Bike, every 20min | Drink — alternate water/electrolyte, ~2 bottles + aid station grabs |
| Bike, every 40min | Gel or half bar → 60–70g carbs/hour, ~5 feeds total. Under-eat here = run collapses. |
| T2 | 1 gel going out |
| Run, every ~5km | Gel (carry 3) + course offerings. Coke in the second half. |
| Item | Why | EUR |
|---|---|---|
| Wetsuit (buy or rent) | Legal at 23°C. Free buoyancy + calm for a new swimmer. | 120–250 |
| Goggles ×2 | Race-morning fog/leak is a €15 problem — solve it now | 25–40 |
| Swim buoy + bright cap | Solo lake swims. Non-negotiable safety. | 25–35 |
| Tri suit | One outfit all day — swim, bike, run. No changing. | 60–120 |
| Bottle cages ×2 + bottles | Eating is the fourth discipline | 20–30 |
| Tubes ×2, levers, pump/CO₂ | A flat without it = DNF. Practice one change at home. | 30–40 |
| Pool pass | 14 swims coming (Tašmajdan / Banjica / 25. maj) | 30–50 |
| Item | EUR |
|---|---|
| Race belt | 10 |
| Chamois cream / Body Glide | 10–15 |
| Gels/bars ×15, one brand | 35–50 |
| Electrolyte tabs | 10–15 |
| Sunglasses | 20–50 |
Total: ~€400–700. All reusable for the next challenge.
Athlete check-in + briefing at Ada. Easy 400m swim. Study transition layout.
Rack the bike (mandatory). Carb-load 8–10g/kg. Feet up, early bed, two alarms.
1.9km · 90km · 21.1km. Finish line at Ada Ciganlija.
Check-in, briefing, bike check-in, body marking, timing chip. Read the athlete guide twice. Half of first-timer stress is logistics, not fitness.
After 1900m your brain is porridge. Memorize your rack row Saturday. Landmark, count, repeat.
Practice twice: peel to waist exiting the water, step and rip. Or accept +90s — you have the margin.
Roll to your back, fix, carry on. This is why you seeded at the back.
Post-swim adrenaline + flat road = the classic blow-up. HR cap 140. Boring wins races.
6+ hours of drinking. Portaloos in transition and at every aid station. Plan for one stop, lose 90 seconds, stay human.
Wetsuit neck, saddle region, tri-suit seams. Body Glide everything twice.
Small towel in T1, socks for the bike. 20 seconds spent, feet saved for the half marathon.
Practice the race wake-up once — the Sep 5 rehearsal starts at race time for exactly this reason.
Same voice from marathon km 32. Same answer: "I chose this." It worked on the Hotel Moskva hill; it works on the lake loop.
Happily broken for 3–4 days. Then a finisher medal on the shelf and a dangerous thought: "what's next?" (See: the hub page has a slot open.)
Five months ago you couldn't run. Then you ran a marathon on five weeks of training.
Now you can barely swim — so obviously you're becoming a triathlete in five weeks,
in a race that starts and ends on the lake outside your door.
It's absurd. It's also exactly your kind of absurd. See you at Ada.