⏵ Course guide · Flagstaff loop trail run
Groovin' in the Aspens runs five distances, 6K through 50K, on a system of Green, Blue, and Black loops through the pines and aspens out of Flagstaff's Fort Valley Trailhead. I will walk you through how the loop system builds each distance first, then give you a pacing and fueling plan for a Flagstaff September morning, plus free calculators to dial in your own numbers.
These facts come from the official race website and its linked UltraSignup registration page. Check the current year details, cutoffs, and aid stations before you commit. Race logistics change year to year.
Every distance is built from the same set of color-coded loops out of Fort Valley Trailhead, so the difficulty scales with how many Blue and Black loops you sign up to run.
The 6K runs on smooth, easy Green trail that surrounds the expo area, a relatively flat course through the aspens built to be very friendly, whether it is your first trail race or a warm-up shakeout before a longer distance the same morning.
The 10K carries 682 feet of elevation gain and the 20K carries 900 feet, both on a combination of singletrack and jeep road. The 30K stacks one Black loop with one Blue loop, and the 50K stacks two Black loops with one Blue loop, so the Blue loop shows up across most of the longer distances as a connecting piece.
Aid station locations are determined closer to race day but are spaced no more than 7 miles apart on course, which is enough to plan a real fueling rhythm for the 30K and 50K without carrying everything you need from the start.
The 20K, 30K, and 50K do not have a single finish-line cutoff. Instead, you must start your last lap by 2:00 PM MST, which changes how you should think about your pacing buffer.
Because the cutoff gates when you BEGIN your final loop rather than when you finish, a slow middle lap can cost you the chance to attempt your last one at all, even if you would have had time to finish it. Use a grade-adjusted pace target for the Blue and Black loop climbs so you know your real per-loop time, not just your flat-ground pace.
A race-time estimate built from your training, checked against your actual first-loop split on race morning, tells you honestly whether the 50K’s two Black loops and one Blue loop are within reach before you commit to starting that final lap.
⏵ Free tools to pace this course
Flagstaff's elevation keeps race mornings cool even in September, but the sun at altitude can warm things up fast once you are a couple hours into the 30K or 50K.
Aim for roughly 45 to 75 grams of carbohydrate per hour on the 20K, 30K, and 50K, using the aid stations spaced no more than 7 miles apart to stay ahead of your needs rather than catching up after a hard Black loop climb.
Sodium in the 300 to 700 mg per liter range covers most runners, and Flagstaff’s altitude and dry air can increase fluid losses even when the temperature feels moderate, so do not assume a cool morning means you can skip sodium planning for the later loops.
⏵ Build your fueling plan
Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and a high-altitude Flagstaff morning 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 course's loop system, and your projected lap splits. Summit Line reads your real training, builds a plan for repeated loop climbing, and rehearses your fueling so race day is something you execute, not guess at.
It scales from a genuinely easy 6K on smooth, flat "green" trail around the expo area up to a real 50K built from two Black loops and one Blue loop. The 10K carries 682 feet of gain and the 20K carries 900 feet, both mixing singletrack and jeep road, so the harder distances are where the elevation and technical footing start to matter.
The 6K and 10K must be completed by noon MST. The 20K, 30K, and 50K work on a "start your last lap by 2:00 PM MST" rule rather than a single finish-line cutoff, so plan your loop splits with that deadline in mind rather than assuming you have until 2 PM to actually finish.
Aid stations are spaced no more than 7 miles apart on course. For the 20K, 30K, and 50K, aim for roughly 45 to 75 grams of carbohydrate per hour depending on your pace and the day’s heat, and keep sodium in the 300 to 700 mg per liter range for a Flagstaff September morning that starts cool at elevation and warms through the day. Build your numbers with the free ultra fueling calculator before race day.
The race runs on a system of Green, Blue, and Black loops through the pines and aspens out of Fort Valley Trailhead, one of Flagstaff’s well-known trail networks. The 6K stays on flat, easy Green trail, while the 10K and 20K mix singletrack and jeep road with real elevation gain, and the 30K and 50K stack multiple Blue and Black loops for their full distance.
The event was previously known as "Gaspin' in the Aspens." Bear Jaw Events, an independent Flagstaff race organizer, resurrected the race by popular demand and renamed it Groovin' in the Aspens, keeping the same aspen-grove trail systems that made the original a local favorite.
The race starts and finishes at Fort Valley Trailhead, 16848 US-180, Flagstaff, Arizona. Early packet pickup is Friday, September 11 from noon to 4 PM at Kickstand Kafe in Flagstaff, or you can pick up race morning before 8:00 AM. Race day registration is available from 6:00 AM until 8:00 AM at Fort Valley Trailhead itself.
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<a href="https://runsummitline.com/guides/groovin-in-the-aspens">The Groovin' in the Aspens course guide</a><iframe src="https://runsummitline.com/embed/race/groovin-in-the-aspens" style="width:100%;max-width:420px;height:180px;border:0;" loading="lazy" title="Groovin' in the Aspens course guide by Summit Line"></iframe>This guide is independent and for planning only. The course details, dates, cutoffs, 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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