Skip to content

Details

This ride is part of the RMCC Challenge Series.

They're baaack! Los Cinco Diablos...or otherwise known as the Boulder Fearsome Five is the nation's toughest century ride. Featuring 16,000+ feet of steep climbing, several dirt/gravel sections, and climbs reaching 8000+ feet in elevation, the Boulder Fearsome Five is truly the nation's most challenging cycling century.

The climbs featured in this event are truly Boulder County's most "devilish" climbs...Flagstaff Mountain Road, Magnolia Road, Sugarloaf Road, Sunshine Canyon/Fourmile Canyon loop, and the SuperJames. In fact, there's probably not many places in the world where you can find as many challenging road cycling climbs within such close proximity to each other as in Boulder!

The primary goal of this ride is to safely complete as many of Boulder County's most challenging climbs as possible. This club event is not a race. It is an opportunity to spend a fun, challenging day on the bike with their fellow RMCC friends. But kudos to everyone who can successfully complete the course! Time to dust off those climbing legs!

2026 Boulder Fearsome Five course: https://ridewithgps.com/routes/53724990

New for 2026:

  1. This year's ride will start at Maxwell Park off of Linden Ave and Wonderland Hill Ave in West Boulder. See map for more details.
  2. The climbing will start with Lee Hill/Deer Trail Rd and SuperJames, then head in a southernly direction.
  3. There's a bit more dirt this year. After descending Magnolia Rd and a < 2 mile section of Boulder Canyon, participants will climb up Chapman Drive (packed dirt) to access Flagstaff Rd.
  4. The climb up Flagstaff Rd will ascend an additional mile past the mailboxes (our previous turn-around point) to the high point of Flagstaff Rd...just because.
  5. Recommended tire size: 28 mm-35 mm. The newer the tire, the better, to minimize the risk of getting a flat tire during one of the dirt/gravel sections.

Start/end location: NEW start location for 2026! Maxwell Park, 598 Linden Park Dr, Boulder, CO 80304 (off of Linden Ave and Wonderland Hill Ave). Street parking available.

Time: Sign-in at 6:30-6:45 AM. Ride start at 7:00 AM. Expected ride duration: 8-12 hours.

Support points: Riders can self-support along the course.

  1. After descending Linden Ave from the Pine Brook Hill neighborhood, participants can self-support at their vehicles at Maxwell Lake Park. Please keep extra water and food in your cars. (38 miles and 6000+ feet of climbing)
  2. Gold Hill Store (48.9 miles and 9000+ feet of climbing)

RMCC membership: Non-dues-paying members are welcome and invited to join us on any ride! After three rides we do require that you join the club: https://www.rockymountaincyclingclub.com/rmcc-membership-application-form

Weather: We are at the mercy of the weather gods. Please keep your fingers crossed for favorable weather.

Please let me know if you have questions:
Mark Lowe (mvlowe5@comcast.net)

Related topics

Events in Boulder, CO

You may also like