⏵ Course guide · Central Wisconsin's steepest test
IRONBULL calls Rib Mountain Trail Races "the steepest test in the Midwest," and the format proves it: 15K, 25K, and 50K runners all share the same loop through Rib Mountain State Park, repeating a climb known as "The Hill" one, two, or three times depending on distance. I will walk you through the loop and repetition first, then give you a pacing and fueling plan built for a repeated climb, with free calculators along the way.
These facts come from the official IRONBULL race page. No elevation gain figure or specific cutoff times are published for this course. Check the current year details and aid stations before you commit. Race logistics change year to year.
All three distances run the same base course through Rib Mountain State Park, a glacially eroded landmark IRONBULL calls a beauty to behold in any season. The 15K covers it once, the 25K twice, and the 50K three times.
The course’s signature feature is a climb nicknamed simply "The Hill," and it stays part of the course every single loop, whether you are running the 15K once or the 50K three times. IRONBULL is upfront that this is still part of the 2026 course, unchanged from the year before. Expect it to feel harder each time you hit it, not easier, as fatigue accumulates.
Aid stations here are cupless, so bring your own hydration system to refill rather than expecting disposable cups. Bone & Joint Sports Medicine staffs a triage and aid station at the start/finish line, providing real injury prevention and recovery support, a notable amenity for a race of this scale.
All racers and volunteers get a free meal and drink at the finish line festivities, with spectators able to purchase onsite. It is a genuinely community-oriented event from a nonprofit organizer that reinvests in local trails, worth sticking around for once you cross the line.
Because every distance shares the same loop, your pacing strategy should scale directly with how many times you plan to climb "The Hill."
If you are running the 50K, you cannot pace "The Hill" the same way a 15K runner does on their single pass. A grade-adjusted pace target for the climb gives you an honest number for what effort you can repeat two or three times, not just survive once. Runners who go out hard on loop one usually pay for it on the final lap.
Your first lap through "The Hill" is real data. A vert-aware finish prediction built off that actual split, extrapolated across your remaining loops, is more honest than any flat-course pace estimate. Adjust your effort after loop one, while you still have time to correct course.
⏵ Free tools to pace this course
Mid-September in central Wisconsin can swing from a cool 7:30 AM start to a warmer afternoon by the time 50K runners are deep into their third loop.
Aim for roughly 40 to 60 grams of carbohydrate per hour on the 15K or 25K, and 60 to 90 grams per hour if you are racing the full 50K. Since this is a cupless race, bring your own hydration vessel so you can actually use the aid stations rather than being caught without a way to carry fluid.
Sodium in the 300 to 700 mg per liter range covers most runners, leaning higher for later loops if the afternoon warms up. Repeated hard climbing on "The Hill" raises your sweat rate more than the mild Wisconsin September temperatures might suggest.
⏵ Build your fueling plan
Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and a repeated-hill September day with the free ultra fueling calculator. Browse the rest of the free running tools at the tools hub.
⏵ Train for it with Summit Line
Get a race-day plan built around YOUR fitness and this exact repeated-hill course profile, whether you are running the 15K once or the 50K three times. Summit Line reads your real training, builds a plan for repeated climbing, and rehearses your fueling so race day is something you execute, not guess at.
IRONBULL brands this "the steepest test in the Midwest," and the format backs it up: the 50K runs three full loops of the same Rib Mountain State Park course, repeating a climb known simply as "The Hill" each time. No elevation gain figure is published, but climbing the same steep section three separate times is a real test of legs and patience, especially on the third pass when your climbing muscles are already worked.
All three distances run the same base course through Rib Mountain State Park: the 15K covers it once, the 25K covers it twice, and the 50K covers it three times. That means every distance shares identical terrain, and choosing a longer distance simply means repeating "The Hill" more times rather than covering new ground.
Mid-September in central Wisconsin can range from cool mornings to warm afternoons. Aim for roughly 40 to 60 grams of carbohydrate per hour on the 15K or 25K, and 60 to 90 grams per hour if you are out for the full 50K, with sodium in the 300 to 700 mg per liter range. This is a cupless race, so bring a hydration system you can refill at aid stations rather than counting on cups being available. Build your numbers with the free ultra fueling calculator before race day.
The official race page does not publish specific cutoff times for any distance. If cutoffs matter to your race plan, confirm the current year’s policy directly with IRONBULL before you commit, since this is not something we can verify beyond what is published.
The course runs through the scenic trails of Rib Mountain State Park, a glacially eroded landmark that IRONBULL describes as a beauty to behold in any season, with colored hardwoods lining the course in September. The signature feature is "The Hill," the same repeated climb every loop, so expect a course that tests your climbing legs more than your technical footwork.
The repeated-loop format has a real upside for a first ultra: after the first loop, you know exactly what the rest of the race holds, which makes pacing more predictable than a point-to-point course. But "the steepest test in the Midwest" is not a marketing exaggeration, so come in with real hill-repeat training rather than assuming a Midwest race means gentle terrain.
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<a href="https://runsummitline.com/guides/rib-mountain-trail-races">The Rib Mountain Trail Races course guide</a><iframe src="https://runsummitline.com/embed/race/rib-mountain-trail-races" style="width:100%;max-width:420px;height:180px;border:0;" loading="lazy" title="Rib Mountain Trail Races course guide by Summit Line"></iframe>This guide is independent and for planning only. The course details, dates, and aid stations come from public sources and can change year to year, so confirm the current specifics with the official race before you register or run. The fueling and pacing advice is general and not medical advice.
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