Marathon • Half-Marathon • Half-Marathon Relay • 5K   |   Historic St. Charles, Missouri   |   Saturday, October 2, and Sunday, October 3, 2021

Challenge Weekend 2021

NEW SCHEDULE* – Saturday, October 2, 2021

5:00 p.m.

St. Charles, Missouri — Frontier Park

*In 2021, the 5K will be on Saturday in order for runners to participate in the Challenge Weekend!

Are you ready?

In 2020, we set out to give our runners a challenge during the strangest year. And as expected, you brought the heat! MO’ Cowbell runners thrived in The Chuck Challenge so we had to bring it into 2021. We are happy to introduce… MO’ COWBELL CHALLENGE WEEKEND!

What the heck is Challenge Weekend? 

Challenge Weekend is a two-part race and an opportunity to challenge yourself even further. Run our 5K course on Saturday evening AND the marathon, half, or relay on Sunday! You’ll receive an extra medal and extra swag! That’s right, walk away from MO’ Cowbell this year with THREE medals.

Well, that’s cool! Is there more? 

Glad you asked! This year the kiddos get to take part in the running action. We love watching families come to race day festivities and have always dreamed of including the little ones. New in 2021 is our first ever Mini MOO Mile, a one-mile fun run for children 10 and under. All participants will receive a t-shirt and medal. 

Aid Stations/Mile Markers

There is water, food and portable restrooms available at start/finish.  There is one aid station halfway along the course serving water and Gatorade Endurance Formula. First aid is available at the start/finish. Post-race food will be provided at the finish.

Weather Policy

Race officials may cancel, delay or change the event in case of extreme weather or other conditions that may affect the safety and health of the participants. In the event of cancellation, refunds will not be issued.


We utilize the ChronoTrack “B tag” system for race timing.  The “B-tag” will be affixed to the back of the race bib. Do not peel off the “B-tag”.  No additional steps are needed prior to the start of your specific race.

Make sure the race bib is attached to the front of your body and is placed on the layer of apparel that will be worn throughout the race. Do not fold or wrinkle your bib prior to attaching it, and make sure it is not covered by a race belt, water bottle, etc.


We are asked all the time if walkers are welcome and we happily say yes! We just ask that everyone maintain a 16-minute mile pace. If you are unable to maintain that pace, that’s ok, we will ask you to move to the sidewalk and finish the race obeying the traffic laws as we will re-open the roads.


All 5K participants receive a full zip jacket, a collectible cowbell, top-quality finisher’s medal, cowbell car sticker (you will want to display), a virtual goody bag, water stations, baggage check, music, course entertainment, post-race food & beverage, medical stations, massage therapy, and of course, spirited neighborhood crowds and volunteers cheering with cowbells. You’d think it’s your birthday with all you get!  (*Please note MO’ Cowbell is not responsible for any materials left along the course or in runner baggage check.)

Age Minimum Requirement

The age minimum requirement is 14-years-old for the full Marathon.  Anyone under 14-years-old with documented running experience may be allowed to race in MO’ Cowbell on a case-by-case bases.  Permission must be granted by race officials. Contact us at


Cowbell trophies are given to both male and female top finishers in first, second and third place. Age group cowbell trophies will be given to the top three finishers (men and women): 19 and under, 20-24, 25-29, 30-34, 35-39, 40-44, 45-49, 50-54, 55-59, 60-64, 65-69, 70+. Overall awards are determined by “gun time”. Age group awards are determined by “Chip” time.

VIP Runner

Upgrade to VIP! A MO’ Cowbell VIP runner receives: prime race day parking, access to a special pre and post-race VIP Area near the start/finish line, exclusive indoor restrooms, personal gear check, complimentary on-site massage and MO’! For ONLY $50 these 150 spots will sell out FAST! UPGRADE NOW!

Need to transfer from one race to another?

We got you covered! Runners may transfer from one race to another through their race profile. There is no refund for a runner who downgrades from a more expensive registration choice/race to a less expensive one. If a runner would like to upgrade to a more expensive race, they will be automatically be charged the difference in entry fee plus an additional $10 transfer fee.

TRANSFER MY RACE  All entry fees are non-refundable.  Sale and/or transfer of race entry/bib numbers is strictly prohibited.