Friday, May 25
Iron Horse Bicycle Classic. Watch or compete as bikers race the train to Silverton. Events throughout the weekend. 7:30 a.m. Durango to Silverton, ironhorsebicycleclassic.com. Through May 27.
Saturday, May 26
Gunnison Growler Weekend. 64- and 32-mile mountain bike rides and events throughout the weekend. Downtown Gunnison, originalgrowler.com. Through May 27.
Monday, May 28
BolderBoulder 10K. Celebrating 40 years, BolderBoulder has created a beloved running culture in Boulder County. Both runners and community members can participate in a full day of fun. Races finish at CU’s Folsom Field. First wave kicks off at 6:55 a.m. For information, go to bolderboulder.com.
Vail Valor Races. Watch or participate in the full marathon, marathon relay, half marathon, five-mile run/walk, or one-mile memorial run. Vail, vailvalorraces.com.
Saturday, June 2
Buena Vista Bike Fest. Road rides of various distances 35-97 miles. 7 a.m. McPhelemy Park, Highway and Main Street, Buena Vista, bvbf.org.
Burning Can Festival at Lyons Outdoor Games. Outdoor game competitions with beer and music to boot. Bohn Park, 199 Second Ave., Lyons, burningcan.com/lyons. Through June 3.
Fire Hydrant 5K and Pet Expo. Walk or run to support homeless pets and the Larimer Humane Society with this dog-friendly event. 8 a.m. The Promenade Shops at Centerra and Chapungu Sculpture Park, 5971 Sky Pond Drive, Loveland, 970-530-2945.
Longmont Triathlon Weekend. Kids-only and beginner triathlons on Saturday; the 38th annual triathlon on Sunday. Centennial Pool, 1201 Alpine St., Longmont, 303-651-8406. Through June 3.
Palisade Gran Fondo. Your choice between two Western Colorado rides: the 40-mile Palisade Piccolo Fondo and the Palisade Gran Fondo. 7 a.m. Peach Bowl Park, 600 Logan Ave. Palisade, palisadegranfondo.com.
Run the Rockies. Half marathon starts at 8 a.m., road 10K starts at 8:30 a.m. Racers must take a shuttle bus from Frisco to the start of the race at Copper Mountain — no racer parking available at start line. 970-668-9133.
American Heart Association Heart Walk. Join thousands to walk or run for heart disease and stroke awareness. There will also be yoga in the end zone. 8 a.m. Broncos Stadium, 1701 Bryant St., Denver, 866-430-9255.
Sunday, June 3
Steamboat Marathon & Half Marathon. Enjoy the sights of the Elk River and Rocky Mountains on your run through Steamboat. 7:30 a.m. Routt County Courthouse, 522 Lincoln Ave., Steamboat Springs, 970-879-0880, steamboatchamber.com.
REVEL Rockies Marathon and Half Marathon. Whether you do half or all the way, a downhill race through the canyons and forests of the foothills. 6 a.m. Evergreen, runrevel.com/rdv.
Big Gay 5K. Walk or run this 5K and show your PRIDE. 9 a.m. Cheesman Park, Pavilion Building, 1900 E. 11th Ave., Denver, denver.biggay5k.com.
Saturday, June 9
Ironkids Boulder Fun Run. For kids who want to get in on the racing action and have some fun. Different distances depending on age and interest. Boulder High School, 1604 Arapahoe Ave., Boulder, ironman.com.
Mount Evans Ascent Race. This race gains nearly 4,000 vertical feet to the top of Mount Evans at 14,264 feet. 6:30 a.m. Echo Lake, Highway 103, Idaho Springs,
Sunday, June 10
Garden of the Gods 10-Mile and 10K Run. Follow a challenging course through some beautiful rock formations. Garden of the Gods, 1805 N. 30th St., Colorado Springs, 719-473-2625, gardentenmile.com.
Ironman Boulder. The classic endurance race in the triathlon mecca of Boulder. 6 a.m. Boulder Reservoir, 5565 N. 51st St., Boulder, ironman.com.
Saturday, June 16
Bacon Burner 6K. When a 5K won’t do, go for 3.8 miles on a paved trail with views of snow-capped peaks and the Dillon Reservoir. 9:30 a.m. Frisco Marina, 267 Marina Road, Frisco, 970-668-9133.
G’Knight Ride. Join more than 2,000 riders for a celebration of cycling. Cruise down Longmont’s scenic greenways, enjoy music, food, beer and a kids’ festival. 3 p.m. Roosevelt Park, 700 Longs Peak Ave., Longmont, 303-319-9882, gknightride.org.
Sunday, June 17
Father’s Day 5K. Celebrate Father’s Day by proving you can keep up with your kids in this 5K run or walk and a one-mile kids run. 8 a.m. 300 E. Foothills Parkway, 970-221-6655.
Father’s Day Classic 10K, 5K, Fun Run. Bring the family to ring in Father’s Day with a run through Arvada. 13150 W. 72nd Ave., Arvada, dads5k.com.
Estes Park Marathon. Offering full and half marathons, 10K, 5K and a kids races. Check the website for race starting lines and times. Estes Park, 970-214-4128, epmarathon.org.
Wednesday, June 20
Crested Butte Bike Week. A whole week of rides through scenic routes and historical areas during a bike week in the home of mountain biking. Crested Butte, cbbikeweek.com. Through June 24.
Sunday, June 24
Bicycle Tour of Colorado. Take a seven-day, 426-mile tour of the Rockies on two wheels, beginning and ending in Leadville. Lake County High School, 1000 W. Fourth St., Leadville, 303-985-1180, bicycletourcolorado.com. Through June 30.
Sunday, July 1
Colorado Firecracker 4K/4 Mile. Celebrate Independence Day early with a fun run, crawfish boil, beer and fireworks. 8 a.m. Erie Rec Center, 450 Powers St., Erie, coloradofirecrackerrun.com.
Wednesday, July 4
Mount Evans Freedom Run 5K. Toast the U.S.A. and support Mount Evans Home Health & Hospice with a morning run. 8 a.m. Evergreen Middle School, 2059 Hiwan Drive, Evergreen, 303-674-6400.
Saturday, July 7
LG Sprint Triathlon and LG Kids Triathlon. A fun sprint triathlon for kids and adults in honor of Laura Genelin. 7 a.m. Eagle Pool and Ice Rink, 1700 Bull Pasture Road, Eagle, lgtri.com.
Enduro World Series Mountain Bike Race. Big Mountain Enduro stops in Keystone for raw and rugged mountain biking. Keysone, bigmountainenduro.com.
Sunday, July 8
Boulder Peak Triathlon. One of the country’s longest and most well-known triathlons for both the novice and professional racer. Boulder Reservoir, 5565 N. 51st St., Boulder, withoutlimits.com.
Friday, July 13
Roger’s River Run 5K. Wear your glow-in-the-dark running gear for this night-time run on the Greenway GLOW. Then stop by Rhythm on the River to boogie down. 7:30 p.m. Boston Avenue, across from Boulder County Fairgrounds, Longmont, 303-776-6050.
Louisville Spaghetti Open Golf Tournament. Finish off a great game of golf with a big bowl of spaghetti. 7:30 a.m. Coal Creek Golf Course, 585 W. Dillon Road, Louisville, 303-666-7888.
Saturday, July 14
Single, Double and Triple Bypass Bicycle Tour. Choose your own adventure with the single bypass starting in Copper, the double starting in Georgetown or the triple taking off from Evergreen. All races finish in Avon, 303-526-3000, triplebypass.org.
Aspen Valley Marathon. Scenic runs — marathon, half and 5K — mostly downhill along the Rio Grande Trail. Aspen Wagner Park, S. Mill Street, Aspen, aspenvalleymarathon.com.
Frisco Triathlon. A different sort of triathlon with a 3K stand-up paddleboard, 12-mile mountain bike ride and a 5K trail run. 9 a.m. Frisco Marina, 267 Marina Road, Frisco, 970-668-5276, townoffrisco.com.
Sunday, July 15
Barr Trail Mountain Race. The race begins at an elevation of 6,570 feet and then gains more than 3,600 feet before returning back to the beginning. 7 a.m. Pikes Peak Cog Railway, 515 Ruxton Ave., Manitou Springs,
Saturday, July 21
Bob Cook Mount Evans Memorial Hill Climb. An iconic bike race on the highest paved road in the U.S. from Idaho Springs to Mount Evans. 320 Chicago Creek Road, Idaho Springs, 303-249-6168, bicyclerace.com.
Courage Classic. Join the community and support the Colorado Children’s Hospital with a two-day, scenic cycling event starting and ending at Copper Mountain. There’s also a 1K for kids. Copper Mountain Resort, 209 10 Mile Circle, Frisco, childrenscoloradofoundation.org/courage-classic. Through July 22.
Friday, July 27
Black Diamond Open Golf Tournament. 18 holes of golf plus other competitions, a team contest, food and prizes. 7:30 a.m. Indian Peaks Golf Course, 2300 Indian Peaks Trail, Lafayette, 303-666-9555.
Saturday, July 28
AUDI Power of Four Trail Run and Mountain Bike Races. Move through the terrain of the four Aspen Snowmass mountains, with a 25K or 50K run for endurance runners, or a 10K. 6 a.m. Aspen Mountain Upper Gondola Plaza., Aspen, 970-925-1220, aspensnowmass.com. Through August 6.
Friday, August 3
Rocky Mountain Half Marathon and 5K. Part of the National Park Half Marathon Series, designed to leave you with the energy to enjoy the rest of the park. 6 a.m. Rocky Mountain National Park, Lake Estes Trail near Community Drive, Estes Park, 435-200-4956. Through Aug. 4.
Saturday, August 4
Enduro World Series Mountain Bike Race. Aspen Snowmass hosts the Big Mountain Enduro finals with some of the best rides in the area. Aspen Snowmass, bigmountainenduro.com. Through August 5.
BEC Triathlon. 400-meter, high-altitude swim in the open water of Nottingham Lake, 15K road bike heading back to Avon, and a 5K run through Nottingham Park. The event also includes a 5K walk/run and a Kids Splash ‘N’ Dash Swim/Run. 8 a.m. Nottingham Park, 1 W. Benchmark Road, Avon, bectri.com.
Ironman 70.3 Boulder. 1.2-mile swim, 56-mile bike, and 13.1-mile run will offer qualifying slots to the 2019 world championship. Boulder Reservoir, 5565 N. 51st St., Boulder, ironman.com.
LAPS Canine 4K. A charity fun-run for dogs, their owners and friends hosted by the League for Animals & People of the Summit. 9:15 a.m. Frisco Historic Park Gazebo, 120 Main St., Frisco, 800-424-1554, townoffrisco.com.
Littleton Twilight Criterium & Bike Fest. A timed bike race on a closed-circuit course that’s just as fun for participants as it is for spectators. 3 p.m. Historic Downtown, Alamo Ave., Main Street, Downtown Littleton,
Sunday, August 5
Lake Dillon Challenge Rowing Regatta. Celebrating the environment, the Lake Dillon Challenge is the highest and most scenic regatta in North America. Frisco Bay Marina, 267 Marina Road, Frisco, 970-409-8435, friscorowing.com.
Saturday, August 11
Aspen Backcountry Marathon. This tough but beautiful race offers full or half marathons run on mountain dirt trails. 6 a.m. Rio Grande Park near downtown Aspen, 970-429-2093, aspenbackcountrymarathon.com.
Georgetown to Idaho Springs Half-Marathon. Take a picturesque run along Clear Creek. 8 a.m. Race starts next to Georgetown Lake in Georgetown, gtishalf.com.
Longmont Sunrise Stampede. A family-oriented two-mile run/walk and 10K run on a certified course raising money for the St. Vrain Valley School District. 8 a.m. Silver Creek High School, 4901 Nelson Rd., Longmont, sunrisestampede.com.
Tuesday, August 14
Transrockies Run. A stage race that takes you or a team on an epic, 120-mile journey from Buena Vista to Beaver Creek over six days. 7 a.m. Buena Vista Heritage Museum, 506 E. Main St., Buena Vista, 866-373-3376, transrockies-run.com. Through Aug. 19.
Saturday, August 18
Pikes Peak Ascent and Marathon. Two tough races only open to qualified runners. 7 a.m. Memorial Park, Manitou Springs, 719-473-2625, pikespeakmarathon.org. Through Aug. 19.
Sunday, August 19
Evergreen Kids Triathlon. Fun, non-competitive races of different lengths for 5- to 13-year-olds. 9 a.m. Buchanan Park Recreation Center, 32003 Ellingwood Trail, Evergreen, 720-880-1219.
Sunday, August 26
Golden Gran Fondo Festival. Grab your friends and watch or participate in one the most challenging road races in the nation. 8 a.m. Parfet Park, 10th Street and Washington Avenue, 765-247-2453.
Friday, September 7
Steamboat Bike Week. Fans of two-wheels head to Steamboat for a long list of activities for bike enthusiasts, including multiple tracks, roadways and county roads. Rides for all ages and intensity levels. Various venues across Steamboat Springs, 970-879-0880, steamboatchamber.com. Through Sept. 9.
Saturday, September 8
Red Rocks Extreme Challenge. Ride in a 33-mile, 62-mile metric century, 100-mile century or the BEAST ride at 130 miles and 13,000 feet of climbing. Ride to defeat ALS. Morrison, redrockscentury.com.