⏵ Course guide · Kansas' oldest trail ultra
FlatRock sends its 50K and 25K fields out and back on the Elk River Hiking Trail around Elk City Lake, Kansas, a technical, rocky singletrack through limestone bluffs with no long hills but plenty to trip you up. I will walk you through the terrain and the dense aid-station spacing first, then give you a pacing and fueling plan for a rocky out and back, plus free tools to dial in your own numbers.
These facts come from the official UltraSignup registration page and the race's own course description. Check the current year details, cutoffs, and registration window before you commit. Race logistics change year to year.
Both distances run out and back on the Elk River Hiking Trail, an accurately measured forest trail that winds through limestone bluffs and rock formations around Elk City Lake.
The race's own course description is blunt about it: "very rocky, no long hills." There is no single defining climb here, but the rock and root-strewn singletrack through the limestone bluffs demands constant attention to footing, mile after mile, in both directions on the out and back.
FlatRock backs up its rocky terrain with genuinely dense aid: 9 stations on the 50K, 7 fully stocked with water, electrolyte drink, and snacks and 2 water only, spaced roughly 3.5 miles apart and never more than 4. The 25K carries 3 fully stocked stations of its own. That spacing means you rarely go far without a chance to refill.
The 50K is capped at 175 runners and the 25K at 75, keeping the technical singletrack from feeling crowded. FlatRock is widely regarded as the oldest trail ultra in Kansas, and finishers are welcomed into that tradition with a date-specific belt buckle for the 50K and the race's own "FlatRock Hall of Pain" Knighting Ceremony.
With no long hills but constant technical footing, pacing here is about managing rock and root terrain evenly across both legs of the out and back, not conserving effort for a climb.
A grade-adjusted pace target for rocky, rolling singletrack gives you an honest number, but fatigue on rocky terrain compounds differently than on smooth trail: tired legs make technical footing more dangerous, not just slower. Plan to run the return leg of the out and back with the same care you gave the outbound leg, even as your legs tire.
Both the 50K's 10-hour and the 25K's 9-hour cutoffs are strictly enforced with no stated grace period. A finish-time projection checked against those limits early, using your actual pace on similarly rocky terrain rather than a flat-trail estimate, tells you honestly whether you are on track.
⏵ Free tools to pace this course
With aid stations rarely more than 4 miles apart, you can carry less and lean more on the course itself than you would at a sparsely aided ultra.
Aim for roughly 40 to 70 grams of carbohydrate per hour, and take advantage of the 9 aid stations on the 50K to run with a lighter pack. On rocky, technical footing, a lighter kit helps you move more confidently through the limestone bluff sections than carrying a full race's worth of supplies.
Late September mornings in southeast Kansas can start cool and warm up by mid-morning, especially exposed along the lake. Dress in layers you can shed at an aid station rather than committing to one temperature for the whole race.
⏵ Build your fueling plan
Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and a densely aided rocky trail 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, this exact rocky Elk River out-and-back profile, and your projected splits against the strict cutoffs. Summit Line reads your real training, builds a plan for technical footing, and rehearses your fueling so race day is something you execute, not guess at.
Widely known as the oldest trail ultra in Kansas, FlatRock runs out and back on the Elk River Hiking Trail, a forest singletrack through limestone bluffs and rock formations. There are no long hills, but the course is described in its own materials as "very rocky," and a technical, root-and-rock surface at 50K adds up over strict 7:30 AM to 10-hour cutoffs. It rewards trail-savvy footwork more than raw fitness.
The course follows the Elk River Hiking Trail around Elk City Lake, an accurately measured forest trail winding through limestone bluffs, rock formations, and picturesque vistas, run as an out and back rather than a loop. The official course description calls it "very rocky" with "no long hills," so the challenge is technical footing and sustained rocky singletrack rather than climbing.
The 50K starts at 7:30 AM with a 10-hour time limit, and the 25K starts at 8:30 AM with a 9-hour time limit, both strictly enforced. On a rocky, technical out-and-back like this, those cutoffs demand consistent footwork through the full distance, not just fitness at the start.
Aid is genuinely dense here: 9 aid stations on the 50K, 7 fully stocked with water, electrolyte drink, and snack-type foods and 2 water only, spaced roughly every 3.5 miles and never more than 4 apart. Aim for roughly 40 to 70 grams of carbohydrate per hour, and lean on that frequent aid access rather than carrying a full race's worth of fuel on a technical, rocky trail where a lighter pack helps your footing.
The field is intentionally small: capped at 175 runners in the 50K and 75 in the 25K. That keeps the trail from feeling crowded on a technical, single-track out and back, but it also means the race can fill, so registering early is worth it if you have your fall race calendar set.
Every 50K finisher earns a unique, date-and-event-specific belt buckle, and every 25K finisher earns a unique award of their own. The race also runs the "FlatRock Hall of Pain" Knighting Ceremony as part of its awards program, a longstanding tradition that reflects the race's status as the oldest trail ultra in Kansas.
Link this guide
Race directors and clubs: link or embed this guide anywhere. It stays current.
<a href="https://runsummitline.com/guides/flatrock-50k">The FlatRock 50K course guide</a><iframe src="https://runsummitline.com/embed/race/flatrock-50k" style="width:100%;max-width:420px;height:180px;border:0;" loading="lazy" title="FlatRock 50K course guide by Summit Line"></iframe>This guide is independent and for planning only. The course details, dates, cutoffs, and registration windows 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.
The timeline
Get the week-by-week countdown for this race: when to build, when to peak, when to taper.
One email with the timeline, plus training notes for this race. Unsubscribe any time.