Tandem Hardtail
Partnering with master bike builder and machinist Colin Reay, the Sea Otter all mountain tandem is a mission to build and race a mountain bike in an almost impossible timeline of 4 days. The tandem is welded from oversized 4130 chromoly tubing for stiffness and features in house CNC machined seat collars, bottom bracket adapters, and stem.
To learn more about the tandem check our sweet features on Pinkbike and Bikepacking.com!
Tandemonium!
A Bike is dreamed
The Sea Otter All Mountain Tandem is Colin’s and I's testament to how quickly a bike can be successfully designed, fabricated, tested, and raced. Colin and I came up with the wild idea to build a tandem at Bike Night in April 2023. I had tried racing the Sea Otter 40k tandem MTB race the previous year on a clapped rigid 26in beach cruiser tandem, and broke the bike during the race. Upon describing last year’s misadventure to Colin, we agreed to embark on the almost impossible task of designing, fabricating, assembling, and racing a bike from scratch with a hard deadline in 2 weeks. After modeling the tandem frame in Fusion 360 and ordering tubing, it was now a waiting game. The days counted down as those 2 weeks of waiting turned into 1 week, which turned into 4 days once the tubing finally arrived.
Time to weld!
It was now game time! Colin and I began work on the tandem Monday night the week of Sea Otter. Working as a team, Colin did the work of cutting and mitering while I TIG welded the frame. Since the tandem is so large and doesn’t fit our conventional Anvil frame jigs, we fixtured the tubes on a custom extrusion jig that Colin and I machined. We also machined a custom T47 to BSA bottom bracket adapter, seat collars to account for the twisting of captain’s seatpost due to higher axial force from the stoker handlebars, and also a custom 5 axis CNC stem. We put in a 100 hours worth of combined effort on the tandem, all while balancing work and school. 3 Days later on Thursday morning, our last weld was completed and the frame was finished!
A bike is born!
Come Thursday noon, the frame and its components were ready for assembly. Due to the tight deadline, all components were scavenged from other bikes and parts bins. We stole and borrowed a fork, wheels, brakes, drivetrain, and seatposts from 3 different mountain bikes. The final build consisted of Pike Ultimate fork, a XT 4 pot front brake, a hydraulic cable pull rear brake, and an AXS drivetrain and dropper post.
The tandem was ready for racing and we made our way to Sea Otter. The tandem received lots of positive attention in the bike industry, including sponsored parts from Paul Components and a couple of article features and offers of collaboration! The Sea Otter festival showcase was a grand success but there was still the race to prove ourselves.
Not everything would go so smoothly! On the morning of the 40k MTB race, Colin I arrived at the start line 10 minutes late, after the pedals stripped out of the non tandem threaded cranks. Tandem specific cranks allow the pedals to self tighten in the direction of pedaling. Our parts bin tandem had regular square taper cranks so 3 of the 4 pedals will unthread when we pedal.
Despite the mechanical setback and apparent loss, Colin and I decided to simply go and enjoy the ride. Past the start line, we were immediately thrown in the deep end as both their bottles were ejected on the braking bumps of the sandy singletrack. With the trial by fire, we learned to trust each other while working together and felt confident enough to begin passing other bikes. I piloted the racing line with precision while Colin coordinated with ease to lean and stabilize the shred sled from the rear. Our teamwork and combined bike handling allowed us to catch and pass the tandem group 10 minutes ahead. Colin and I crossed the finish line and couldn't believe our eyes when we saw that they had placed 2nd on the podium!! After the race I was surprised to learn that it was actually Colin’s first time riding a tandem! How wild! Colin’s excellent stokering and teamwork definitely wouldn’t suggest that!
Our bike's success both at the showcase and race received invitation to exhibit and race Grinduro Shasta, where the Tandem found its way onto the podium once again! Ambitious future plans are in the works so stay tuned… You may see the tandem on the Great Divide Mountain Bike Route next summer!
