⏵ Course guide · Fixed-time trail race
The Napa Lapa Trail Adventure flips the usual formula: instead of racing a set distance, you run a hilly 4.16-mile loop at Skyline Wilderness Park as many times as you can within 12, 6, or 3 hours. I will walk you through the loop format first, then give you a pacing and fueling plan built for repeated climbing over a long fixed-time window. There are free calculators along the way to dial in your own numbers.
These facts come from the official Inside Trail Racing event page. Check the current year details, cutoffs, and aid stations before you commit. Race logistics change year to year.
You pick your division, 12, 6, or 3 hours, and repeat a 4.16-mile loop with 815+ feet of gain for as long as your window allows. One lap or twenty, once your time is up, you are a finisher.
Each 4.16-mile loop carries about 815 feet of gain, run on fire trail and moderately technical dirt, with long smooth hills and swooping descents mixed with some twisty single and double-track. There is no easy recovery lap here: every trip around is a genuine climb.
In the final 40 minutes of your division, the course opens a short 0.34-mile "small loop" so you can bank extra distance without starting a full lap you cannot finish in time. Deciding whether to head out for one more big loop or wait for the small loop to open is part of the mental game here.
A full aid station sits at the start/finish, and a water-only station sits at mile 2 of each loop, meaning you pass a refuel point about every 2 miles. That density lets you run lighter than a typical point-to-point ultra, staging gear at the start/finish instead of carrying everything for the whole window.
The math here is different from a fixed-distance race: your goal is maximizing total distance across repeated 815-foot climbing laps, not hitting a finish line as fast as possible.
Since you decide how many laps to run, the temptation to push an early lap hard is real, but it borrows directly from laps five, six, and beyond. A grade-adjusted pace target for the climbing gives you an honest per-lap effort you can actually sustain across a 12-hour window, rather than a number that only works once.
Because you get real split data after lap one or two, use it to build an honest projection of how many full laps you can complete before your division ends, plus whether the small loop is worth banking at the finish. Check that math against the 30-minute-before-cutoff rule for starting a new loop, so you never head out on a lap you cannot legally finish.
⏵ Free tools to pace this course
A 7:00 AM start on the 12-hour division means finishing around 7:00 PM, a long day of repeated climbing through the full range of a Napa August day.
Aim for roughly 60 to 90 grams of carbohydrate per hour. Because you pass through the full aid station every lap, roughly every 4 miles, you can plan your intake by lap count instead of guessing at distance between stops the way you would on a point-to-point course.
Sodium in the 300 to 700 mg per liter range covers most runners, leaning toward the higher end as the day heats up through the middle laps of a 12-hour effort. Skratch Labs and Spring Energy products are on course at both aid points, so use the frequent access to adjust intake lap by lap rather than committing to one number for the whole day.
⏵ Build your fueling plan
Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal division, and a warm Napa summer 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, this exact 815-foot loop profile, and your projected lap count. Summit Line reads your real training, builds a plan for repeated hilly laps, and rehearses your fueling so race day is something you execute, not guess at.
It is Inside Trail's first fixed-time event: instead of racing a set distance as fast as possible, you run a 4.16-mile loop with about 815+ feet of gain as many times as you can within your chosen window, 12 hours, 6 hours, or 3 hours. Finish one lap or twenty, you have officially finished as a "Napa Lapper" the moment your time runs out.
Each 4.16-mile main loop carries about 815 feet or more of gain, so every lap is a real climb, not a flat recovery loop. Over a 12-hour effort with repeated laps, that climbing adds up fast, which is the whole point of a fixed-time race on hilly terrain like Skyline Wilderness Park.
With divisions running up to 12 hours and repeated 815-foot climbing laps, treat this like any other long ultra effort. Aim for roughly 60 to 90 grams of carbohydrate per hour, and sodium in the 300 to 700 mg per liter range, adjusting upward if the Napa summer day runs hot. The single aid station at the start/finish plus the water stop at mile 2 mean you pass a refuel point roughly every 2 miles, so you can travel lighter between stops than a typical point-to-point ultra. Build your numbers with the free ultra fueling calculator before race day.
There is no traditional finish-line cutoff since you choose your own division length: 3, 6, or 12 hours. All courses close at 7:00 PM regardless of division, and each loop closes to new starts 30 minutes before your division's end time (for example, if you are in the 6 hour and want to start another lap during the 12:00 PM hour, you must pass the timing mat by 12:25 PM). Plan your last full lap around that 30-minute buffer rather than your official end time.
Skyline Wilderness Park has 25 miles of multi-use fire road and singletrack of various skill levels. The race loop mixes fire trail and moderately technical dirt trail, with long smooth hills, swooping descents, and some fun twisty single and double-track, true to Inside Trail's reputation for hilly courses.
The format is beginner-friendly by design: you can drop to a shorter division if the 12-hour distance intimidates you, and the frequent start/finish aid access means crew, mental breaks, and gear swaps are easy. The 815-foot-per-lap climbing is real, though, so come with some hill training rather than treating it as a flat lap-counting exercise.
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<a href="https://runsummitline.com/guides/napa-lapa-trail-adventure">The The Napa Lapa Trail Adventure course guide</a>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.