VIPER 100 mile / 107k / 53k / 25k —

Welcome to Viper, an unforgettable ultrarunning experience inside Shelby Farms Park in Memphis, Tennessee—one of the largest urban parks in the United States.

Viper offers four race distances: the Viper 100 Miler, Viper 107K Night Race, Viper 53K, and Viper 25K, giving runners everything from an introduction to trail racing to a full 100-mile ultramarathon.

At the heart of Viper is our 33.4-mile loop, a highly runnable course that combines smooth paved greenways with winding dirt trails throughout Shelby Farms Park. The course takes runners past lakes, through wooded sections, across wide-open areas of the park, and along some of Shelby Farms' most recognizable trails. With a mixture of pavement and dirt, Viper is designed to keep runners moving and makes an excellent race for experienced ultrarunners chasing a strong performance or runners stepping up to a new distance.

The Viper 100 Miler takes runners through three 33.4-mile loops to reach the 100-mile finish. It's 100 miles of endurance, determination, and seeing Shelby Farms transform from daylight to darkness and back again.

For runners who love the night, the Viper 107K offers its own unique challenge. Starting Friday evening, runners head into Shelby Farms as daylight disappears and experience the park almost entirely under headlamp. Finish the 107K and earn a Viper 107K finisher buckle.

The Viper 53K gives runners one complete trip around the 33.4-mile course, making it an excellent first ultra or a fast, runnable challenge for experienced runners. The Viper 25K provides a shorter taste of the Viper experience while still giving runners the opportunity to experience the trails, greenways, lakes, and atmosphere that make Shelby Farms such a special place to run.

And Viper isn't just a race—Shelby Farms Park makes this an experience for the entire family.

While runners are on the course, crews, families, and spectators can explore everything the park has to offer, including lakes, restaurants, coffee, playgrounds, fishing, horseback riding, paddle boats, kayaks, canoes, disc golf, miles of trails, and plenty of places to relax and watch the race unfold. You may even catch a glimpse of the park's famous buffalo herd along the way.

Located in the Memphis area, Viper also gives traveling runners the opportunity to turn race weekend into a trip—experience Shelby Farms Park, explore Memphis, enjoy some of the best food in the South, and then take on an ultra unlike anything you've raced before.

Four distances. One incredible venue. One Viper experience.

100 Mile | 107K Night Race | 53K | 25K

Come experience Viper at Shelby Farms Park in Memphis, Tennessee.

Moccasin 24 Hour Run

Get ready to run as many miles as you'd like in the Moccasin 24 hour run. The course will be a 4 mile loop on the Wolf River Trails in Memphis, TN. Once we start the run, the clock will tick down from 24 hours all the way to zero, which will end the run. You are welcome to run as many miles as you can, as fast or slow as you want, and at whatever pace or time you want. We will have a large canopy tent with walls up at the Start/Finish line where we will all gather under and hang out. This is where you'll rest before you run again. You are welcome to bring your own canopy tent and personal aid station as well. You can start at any time during the 24-hour window so if you don't make it for the start of the race, then you can still show up 3 hours later and jump in the run. What better way to end the year by running some big miles. Can you run 100 miles under 24 hours? Can you run 52 miles and earn a buckle? Come see the trails alive at night with Christmas lights and decorations. (all lights are battery operated so there is only so much we can do). Come hang out and sit by our bonfire, eat smores, and tell Christmas stories all night.

24 hour run starts at Noon.

Family fun 4 mile run

On Friday night, December 26th, we will have a 4 mile run only. This run/walk will be for children of all ages with a parent/guardian. All registered runners will receive a medal at the end of their run. This is a perfect run to introduce kids into trail running. We will have the trails decorated with Christmas lights and maybe a few more fun Christmas surprises along the way.

Western States qualifier
- 100 miler

Mark Your Calendar – The Mamba 100 Is Back!

Get ready for the epic return of the Mamba 100—a celebration of endurance, community, and unforgettable achievement! Whether you’re chasing a PR, tackling your first ultra, or going for that sub-24-hour buckle, this fast and fun course is built to push your limits and deliver lasting memories.

Why Run the Mamba 100?

This isn’t just a race—it’s a movement. With a scenic, low-elevation loop along the Wolf River, a crew-friendly layout, and an electric atmosphere, the Mamba 100 delivers everything you love about ultrarunning:

Speed-friendly singletrack
Unmatched camaraderie
Awesome post-loop energy
Swag that actually slaps

Finish Time Limits (Earn Your Buckle or Medal):

100 Miler: 34 hours
100k: 22 hours
50k: 10 hours
25k: 8 hours

Course Overview:

14.35-mile loop on scenic Wolf River trails
Mostly singletrack with low elevation gain

Loop Breakdown:

100 Miler – 7 loops
100k – 4 loops + starter loop
50k – 2 loops
25k – 1 loop

Race Day Perks:

Crew Heaven: Set up canopy tents at the Start/Finish for prime cheering and support between loops.
Party Vibes: Great music, tasty food, and a high-energy village atmosphere after every loop.
Motivation Everywhere: Fellow runners, friends, and spectators create a wall of encouragement every time you pass through.
Sub 20 hr. and Sub 24 hr. 100 mile buckles

Swag Highlights:

100 Mile - Hooded puffer jacket, Sweatpants, Backpack, long sleeve shirt, Hat (pick one)

100k - Sweatpants, Hat, Backpack (pick one)

Bonus: Your race packet comes loaded with surprises to make this event even more memorable!

ChatGPT Image May 8, 2026, 09_03_32 AM_edited.jpg

Ignite your competitive spirit with the exhilarating Cobra Den Trail Series, featuring four unique races amidst the stunning Tour De Wolf and Wolf River Trails in Memphis. Commencing with the striking Cape 5k and 10k on June 13, 2026, followed by the thrilling Samar 4 and 8 milers, the dynamic Caspian 5 and 10 milers and ending with the challenging King 7 miler and Half Marathon, this series promises an adrenaline-filled summer.

Expect a live, vibrant atmosphere, with rocking music, water/aid stations stocked with energizing snacks and cooling towels. All races are chip timed, with results announced on UltraSignup.
All participants receive a signature T-shirt along with a medal for each race.

Can't make it for an in-person race but still want to participate in the series? Then join us for our virtual Cobra Den Trail Series. All participants receive a signature T-shirt along with a medal for each race.

Our goal is inclusivity, so we've made cutoffs loose. However, consider the Short Series if you can't maintain a 17-min/mile. For Long Series, 20-min/mile cut-off applies.

IF you can't run the entire series, you can run each of these races individually as it's own race.

COBRA DEN WINTER TRAIL SERIES

Four Races. Two Trail Systems. One Winter of Trail Running.

Don’t let winter slow you down. The Cobra Den Winter Trail Series brings four trail races to Shelby Farms Park in Memphis, Tennessee, from December through February, giving runners a reason to stay motivated, compete, and hit the trails all winter long.

The series takes runners through two of the premier trail systems in the Memphis area—the Wolf River Trails and Tour de Wolf Trails at Shelby Farms Park. Each race offers two distances, allowing runners to choose between our Short Series and Long Series and compete across all four events.

SHORT SERIES

Forest 7 Miler – December 12, 2026
Monocled 5 Miler – January 23, 2027
Arabian 4 Miler – February 13, 2027
Anchieta 5K – February 27, 2027

LONG SERIES

Forest Half Marathon – December 12, 2026
Monocled 10 Miler – January 23, 2027
Arabian 8 Miler – February 13, 2027
Anchieta 10K – February 27, 2027

The Cobra Den Winter Series starts with the longest race of the season and progressively works toward shorter, faster distances. It's a unique format that challenges runners in a different way at every event—from the endurance required in December to the speed you'll need when the series championship comes down to the final race in February.

RACE THE SERIES

Register for the complete Short or Long Series and take on all four races while saving compared to registering individually. Series runners earn points at every event based on their performance, with points accumulating throughout the winter toward the Cobra Den Winter Series Championship.

You don't have to compete for the championship to be part of the series. Come chase PRs, experience new trails, stay in shape through the winter, or simply enjoy four mornings of trail running with the Mamba community.

Each individual race will also feature overall male and female awards and age-group awards, so every race provides another opportunity to compete.

TWO INCREDIBLE TRAIL SYSTEMS

Half of the series takes place on the Wolf River Trails, with the other half on the Tour de Wolf Trails at Shelby Farms Park.

That means you aren't running the same course four times. Each venue brings its own terrain, personality, and challenge. Expect dirt trails, wooded singletrack, roots, turns, changing winter conditions, and everything that makes trail racing different from simply running another road race.

And because it's winter in Memphis, you never know exactly what race morning will bring. It could be cold and crisp, muddy and wet, or absolutely perfect trail-running weather.

That's part of the challenge.

CAN'T MAKE IT TO MEMPHIS? GO VIRTUAL.

Runners from anywhere can take on the Cobra Den Winter Series Virtual Challenge.

Complete each of the four races during its designated race weekend from wherever you live—road, trail, greenway, or treadmill. Virtual runners receive an official Cobra Den Winter Series shirt, virtual race bib, and our special four-piece Snowman medal, with one piece representing each race in the series.

TAKE ON THE DEN THIS WINTER

Four races. Four different challenges. Two of Memphis' premier trail systems.

Run one race or take on the entire series.

December 12, 2026 – February 27, 2027
Shelby Farms Park & Wolf River Trails
Memphis, Tennessee

Stay motivated. Race all winter. Earn your points. Chase the championship.

Welcome to the Cobra Den.

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VIPER 100 mile / 107k / 53k / 25k —