SOC13: Dirty Sixer Builds 36″ Wheeled MTBs for the Exceptionally Tall
For a while now, 36 inch wheeled mountain bikes have been sort of a gimmick, or concept bikes for normal sized humans that takes the bigger is better wheel mantra to the extreme. Though if 29ers are more proportional to taller riders, than it should make sense that 36ers are more proportional to really tall riders, right? That’s that way David from Dirty Sixer sees it. The Dirty Sixer is a purpose built 36 inch wheeled mountain bike for riders starting at 6’5″. David himself is 6’6″ and is on the small size for his bike which was raced in the Sea Otter XC race by his tester who is 6’10″!
Building a bike for someone who is a full foot taller than the average human is certainly a challenge and resulted in some very interesting custom parts for the Dirty Sixer.
The crazy part is that most of the 36 inch wheeled bikes we’ve seen really look like the wheels are huge. In order to provide stand over clearance, the tubes are drastically bent but David’s customers have no stand over problems. Under Dirty Sixer’s customers, you may have to look twice to realize just how big the wheels really are.
Built by Dmitry Nechaev who founded Triton Bikes in Russia, and designed by David in California, the Dirty Sixer was built in Titanium and welded up in a week’s time though it had been in development for a few years. The welding was all pretty tidy and had already been torture tested by David’s 6’10” pilot. The bike survived, the seat post – not so much. Building a tall man’s bike is about more than just stuffing comically large wheels in an oversized frame. The Dirty Sixer has quite a few custom bits to actually perform well under such a big rider like the CNC machined disc brake adapters to run Santana tandem 10 inch disc brake rotors on their custom truss fork which runs a 135mm, 20mm thru axle hub. Big guys need big brakes.
Other custom bits include the 220 mm ISIS JK Mountain bike cranks from Joseph Kuosac, which are sold through Lennard Zinn’s Big & Tall Bike Shop. The cranks are mounted to what may be a first – a 100mm wide eccentric bottom bracket to provide the proper Q-Factor for such a big rider.
Dirty Sixer rolls on Nimbus Stealth Unicycle rims laced to Phil Wood hubs, a 185mm hub in the rear, and the aforementioned 135 in the front. Tires are a 36x 2.25 made by Vee rubber for a batch that was commissioned by Walt from Waltworks. Probably the only 36 inch tire that is tubeless ready, the 36 TPI tires weigh in at 1625g a piece and will set you back $125 – but they are also around a pound lighter than the other 36s on the market.
The frame has fork bumpers to keep the truss fork from denting the top tube when the full weight of a 36 inch wheel comes crashing down on it. Built with a 49.6mm head tube, the truss fork has a full 1.5 inch steerer to keep things stiff. Not seen on this bike, but something David is working on for the future bikes are handle bars that are designed for big guys as well. Instead of using a 31.8mm clamping surface and tapering down to the grips, David’s bars will be a full 31.8 all the way through. Companies like Felt have used 31.8 straight bars on their bikes, but David’s will be a riser bar, and he says the larger diameter is better for tall guys because they have such big… hands. Of course this will take some custom solutions for grips and shifter and brake mounting, and we’re looking forward to see what he has up his sleeve.
As David was half joking about at the show, let your local NBA player know that he has his next bike.