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Mt Tam Double Century




The 200-mile Mt. Tam Double Century is now open for registration.   Register early to secure your spot. There is a 300 rider limit.

If you register before July 12 (cutoff subject to change), you will receive free concierge mailing  of your registration packet about 2 weeks before the event.  Skip check-in lines and head straight to the starting line! 

If you register for the Double Century after the cutoff date, you will be need to check-in at the registration booth before riding.


Updates for 2018

The course is subject to change at any time. Please carefully read the course description in your registration packet. Use only official maps and cue sheets.  
Check back here often for updates on the routes, maps and other important information.
Registered riders will receive updates via email.
Follow us on Facebook and Twitter for quick updates.

Start Time

  • There is a mandatory mass start at  5:00 AM.  No one may start before  or after that time.  
  • If you received your packet in the mail, head straight to the start line.
  • If your need to pick up your packet or transfer a registration, visit the registration booth between  4:00 and 4:45 AM.


  • You are not permitted to start riding before 5:00 AM.   NO EXCEPTIONS.  

  • RFID Tags will be issued to all riders.  You MUST affix the tag to your helmet as per instructions included in your packt

  • If you fail to pass through the RFID reader at checkpoints, you will get a DNF (Did Not Finish) and will not get Triple Crown Credit. No exceptions.

  • Bib numbers may also   be recorded at checkpoints.

  • If you RFID tag is not recorded it will result in a DNF. Check the open/closed times at each stop 

Cutoff times


  • Bay Hill/Coleman loop closes at 3:00 PM. for all Double Century riders.  NO EXCECPTIONS
  • Course closes at 10:00 PM.
  • If you ride slower than 11.5 mph average, you may not make the Coleman Valley Cutoff. You may bail out onto the Classic Century course. If you bail out or need SAG, you  will get a DNF.


Light Requirement

  • The Mt. Tam Double Century will begin at 5 AM in the dark and could, depending on your speed, potentially end in the dark.
  • You MUST have working lights for the start of the Mt. Tam Double Century. No exceptions.  If you do not have lights, you will get a DNS (Did not Start)
  • You MUST use lights after 8:00 PM. 

Lights & Drop Bags

The Marin Cyclists will provide paper bags and marker pens for you to drop your lights and other gear and have them forwarded for later pickup.  

Any bags not picked up as the course closes will be SAGed to the finish.  Bags not picked up after the event will be returned to riders via mail ($10 fee). 

Aero Bars

Aero bars are permitted but not recommended. Please do not use aero bars when riding in pace lines.


You will receive a full-color, water-resistant map with cue sheet in your rider packet.

Official Map is HERE

Course Description

The MTDC begins on flat-to-rolling terrain before a 1.4-mile, 430-foot climb to the Big Rock summit of Lucas Valley and a thrilling descent through the redwoods into the ranches and grasslands of West Marin. Here the route parts ways with the other courses, winding south and east to the town of Fairfax and the ascent to the top of Mount Tamalpais (Tam), which begins on Bolinas-Fairfax Road. The narrow and twisting road levels out as it approaches a golf course and begins to climb again to the top of Pine Mountain, where you will find the first rest stop.

From Pine Mountain, the road descends in a series of tight turns with a decreasing radius to four miles of rollers ending at a dam at Alpine Lake. A three-mile ascent takes riders to the ridge where we continue over the top to and a winding descent down to Highway 1 at the Bolinas Junction.  We turn left to travel South on Highway 1 past the Bolinas Lagoon and through Stinson Beach to a left turn at Panoramic.  The open switchbacks allow beautiful views of the Pacific all the way to the top where it enters the forest and then begins to a sweeping descent  back with a few rollers to Highway 1 North. The turn here is a very sharp right.  Use caution as car traffic has the right of way an can approach at high speeds.  Highway descends to Muir Beach and  our second Rest stop at the Golden Gate Stables.

We then continue North again passing the Bolinas Lagoon passing Olema and into Pt Reyes Station, where you will find the third rest stop.  The course then continues north on Highway 1 and then onto Point Reyes/Petaluma Rd, following the flat creekbed inland to Platform Bridge Road, where you will make a left turn to continue on Petaluma Point Reyes Rd. and traveling inland past the Nicasio Reservoir. After a short climb and gentle descent past the Marin French Cheese Factory to Hicks Valley Rd. where turn left and find our rest stop at the Historic Lincoln School .  Continuing on Hicks Valley Rd the course turns left on Marshal Petaluma Rd. to the iconic Marshal Wall. The climb start off steep and  continues for about 3 miles with breathtaking views at top where you can look south and see the Mt Tam in the distance.  The course continues onHighway 1 and the small town of Tomales. At the town center, the course turns left on Dillon Beach Road and continues to Valley Ford-Franklin School Road and a right turn on Highway 1 (away from Bodega), taking you to Valley Ford, site of the fifth rest stop and third checkpoint.

The course continues west on Bodega Highway to Bay Hill Road, which offers a grand view of the Pacific Ocean from the crest. A quick descent on rough road leads to some highly scenic miles of coastline before the route turns onto Coleman Valley Road and a long and steep climb with false summits and stunning views.

At the top of the Coleman Valley Loop, you will find  the fourth checkpoint in small rest stop stocked with water, Gatorade, and energy supplements (gels, bars, etc). A 400-foot descent leads to yet another climb and a long, technical descent on Joy Road. USE EXTREME CAUTION on this winding and potholed stretch, which eventually leads to wide-shouldered roads and the sixth rest stop in Valley Ford.

The ride continues over scenic and sparsely traveled roads to the short but steep Middle Road climb, with another thrilling descent to the S curve at Whittaker Bluff.  It then crosses over Highway 1 to Fallon Two Rock Rd. which you will follow to a right turn at Alexander Rd. and then a left back onto Tomales-Petaluma Rd for the trip back down Chileno Valley Rd.   A rest stop awaits at the historic Laguna School.  Make a left turn at the intersection to travel into Petaluma and the RFID checkpoint  at Windsor and D. Street. We head back west to NIcasio over new pavement with a  wide shoulder  most of the way taking riders past the Cheese Factory to a slight climb and a very fast descent to Nicasio Reservoir and Nicasio Valley Road. A relatively flat stretch lead to the fifth and final rest stop at the Nicasio Schoolhouse.

A few miles later, riders begin the climb back up Lucas Valley Road to Big Rock. Riders should exercise caution on the DEMANDING DESCENT FROM BIG ROCK AT LUCAS VALLEY ROAD. This descent has several sharp left-hand turns with a decreasing radius. The remainder of the route is almost all downhill to the finish.

Rest Stops & Rest Stop Food

  • For the Mt Tam Double Century riders only, each rest stop will have the normal fare, as well as Hammer Gel (packets), Heed, Perpetum and Sustained Energy (SE). If any of these are "must have" please bring your own.
  • There will be sandwiches and/or burritos available at the Valley Ford Rest Stop for the Double Century riders.
  • Some sandwiches and burritos MAY be available at Petaluma, however, this is not guaranteed.
If you need a particular item or drink, please bring it yourself.  We cannot guarantee availability and we work hard to avoid food waste.


SAG and Course Marshals

Course Marshals are only on the Classic Century sections of the DC course.  There will be SAG vehicles on the entire DC course.  Because it's a long course and the SAGs become very spread out as the day progresses, response times may be long.

Check-In at Finish

The official finish is through the same gate that you left fairgrounds.  An RFID reader will  record your finish time.

Post-Ride Meal

Most of the Marin Century fanfare wraps up around 6:00 PM. We will have a hot meal for DC riders who arrive after 6:00;  however, certain menu items may not be available.  Follow the lanterns to Exhibit Hall.  There will be bike parking available at the Exhibit Hall 

Ride Time Results

We will post ride times on our website a few days after the event. We will announce the posting on Facebook and Twitter.  Follow us for updates and news before the event.

DC Jersey

Jerseys can be preordered during registration, added after registration, or purchased after the ride.   
You will only receive your jersey if you finish the Mt Tam Double Century, your jersey will be mailed to you (they will not be available at the finish line. 
If you receive a DNS or DNF, you will receive a refund for your preordered jersey.

DC Volunteers and Triple Crown Volunteer Credit

The Marin Century and Double Century are organized and run entirely by volunteers. We love our volunteers, and always appreciate those with riding experience.  You know the challenges cyclists face and what they appreciate!  

DC riders may earn Triple Crown Volunteer Credit for volunteering at the Marin Century.
Volunteer opportunities that specifically support  the  DC are available here.  
Other volunteering  opportunities are also available here.  

Workers Ride

Volunteers are welcome to ride the Workers Ride, which includes a Double Century.  The Double Century Workers Ride qualifies as a Triple Crown event.  Registration for the Worker's ride will open on August 5.  Please see the Calendar on our website to register.

The workers double course will close at Midnight. 

California Triple Crown

Click here for more info on the CA Triple Crown