Latin America's oldest and most traditional MTB marathon — since 1993, held every September in the historic iron-mining mountains around Mariana, Minas Gerais.
Build Your Personalized Race Fueling Plan — $19General, evidence-based guidance. Numbers should always be personalized to sweat rate, body mass, fitness and weather.
60–90 g/hr of mixed-source carbohydrate (glucose : fructose ~1 : 0.8) for most trained riders, weighted toward liquid and gel for the technical sections where chewing is unsafe. Trained guts can push toward 100 g/hr on longer marathon distances.
17–34 fl oz/hr adjusted for the day's temperature. Cool-morning riders systematically under-drink in the first two hours and pay for it in hour three or four. Drink to the clock, not to thirst — especially on the cold start.
500–1000 mg of sodium per liter of fluid as a default. Salty sweaters and warm afternoon-half riders should push toward 800–1200 mg/L. Under-salting is the most common cause of mid-race cramping on Iron Biker's steep climbs.
3–6 mg/kg body mass, split between pre-start (with breakfast) and a mid-race dose at the base of the biggest climb. A 154 lb rider targeting 5 mg/kg takes ~200 mg pre-race and 150 mg mid-race.
Every stop is a bottle swap first, calorie top-up second. Rehearse a one-minute stop in training so it stays one minute on race day. Pre-mixed bottles in a team box (or friend at aid 1 + aid 2) save 3–5 minutes across the day.
1–4 g/kg carbohydrate 2–4 hours before the gun, from familiar low-fiber, low-fat foods. A 154 lb rider targets 140–280 g CHO. Pão de queijo + banana + honey or arroz + mel are proven Brazilian options — no experiments on race morning.
Fuel BEFORE entering technical sections and IMMEDIATELY after exiting them — never force intake with both hands on the bar. Set a 15-minute alarm on the head unit as a backstop. On climbs, sip constantly and take a gel every 20 min.
Within 30–60 minutes of the finish: 1.0–1.2 g/kg carbohydrate and 0.3 g/kg protein, plus 150% fluid replacement. Iron Biker's 3-day format means recovery nutrition on day 1 (Friday warm-up) shapes day 3 (Sunday marathon) — do not skip it.
Grams and millilitres per hour for each phase of the race. Personalize to your sweat rate, body mass and conditions.
Iron Biker Brasil Sunday marathon (37–56 mi, 4–8 hr) — targets for a mid-pack finisher
0 → first aid (~9–16 mi)·0:00 → ~1:00
Caffeine: 150–200 mg 20 min pre-start (with breakfast option)
Focus: Do NOT chase early moves — Iron Biker punishes riders who match early surges. Cap effort at high Zone 2 / low Zone 3 HR. Lock in a 15-min intake alarm from km 0.
First to second aid (~16–31 mi)·~1:00 → ~2:30
Focus: Force calories BEFORE entering rock gardens and IMMEDIATELY after exiting them. Watch how the gut is tolerating the intake in warm dust — pull back 10 g/hr if bloated.
Second to third aid (~31–43 mi)·~2:30 → ~4:00
Caffeine: 100–150 mg at the base of the biggest climb
Focus: Fixed HR / RPE ceiling. Force calories even at reduced appetite. Every aid stop: bottle swap first, calories second, do not linger.
Third aid to finish (~43–56 mi)·~4:00 → finish
Focus: Ride to power / HR, not to feel. Late-race under-fueling is where riders break — reset the 15-min alarm even if you 'know' the finish is close. Stay conservative on rutted descents.
Finish line to team box·T+0 → T+60
Focus: Recovery starts the moment you cross the line. Compress, shade, elevate. If riding Friday–Saturday too, this recovery window is what makes Sunday's marathon possible.
Aid station spacing and mid-race distances are provisional — confirm the exact 2026 marathon layout, cutoffs and category-specific distance in the current-year Manual do Ciclista on ironbiker.com.br. Individual sweat rate can shift fluid and sodium targets by ±30%; personalize with a pre-race sweat test.
You cannot safely open a gel in a rock garden. Riders who skip a scheduled feed 'because the trail is technical' arrive at the next open section already 15 g behind — front-load instead.
Cold-start hours suppress thirst even as sweat losses build in the first climbs. Structured intake matters MORE in the cold, not less. Force one full bottle before you feel warm.
Technical MTB burns glycogen faster than steady road tempo at the same average power. Iron Biker intake targets should sit at the top of the recommended range, not the bottom.
Iron-rich dust plus long time-on-course amplifies GI risk. Race only what you have trained on 4+ hour rides — even a familiar-looking new gel is a bad bet.
Thirst under-reports fluid deficit by 1–2%. On a 6+ hour Iron Biker day, that gap compounds into cramping and cognitive fog by hour 5.
The 3-day format tempts riders to celebrate Friday and Saturday and 'save' the discipline for Sunday. Under-fueled recovery on Friday shows up on Sunday's queen climb, not before.
Rutted iron-ore descents reward committed line choice more than heavy braking. Practice descending fatigued in training — Iron Biker descents come after 3+ hours of climbing.
Iron Biker updates its route regularly. Do not plan aid mileage, climb sequence or checkpoint spacing off prior years — confirm from the current-year Manual do Ciclista published on ironbiker.com.br.
A practical race-week checklist: carbs, hydration, sodium, caffeine and race-day supplies — print it or keep it on your phone.
Free calculators, checklists and articles to help you personalize your Iron Biker plan.
Every athlete is different. FTP, finish time, body weight, sweat rate, weather, nutrition preferences and race goals all change what you should eat and drink.
FuelQ Pro builds a personalized race fueling strategy tuned to your ride — carbohydrate, hydration, sodium, caffeine and recovery, mapped to the course.
A Race Fueling Plan gives you a personalized strategy for this event. The free checklist helps you prepare the basics first: race-week setup, 48-hour prep, race morning, hydration, sodium, caffeine, aid stations, and backup calories.
