Something New is Brewing in Bend…
Words & Photos by Chili Dog
If you’re familiar with the off-road vehicle world, chances are you’ve heard of Thuren Fabrication before. Founder, Don Thuren is a life-long tinkerer and fabricator who made a name for himself building top of the line suspension systems for full size Ram trucks. For people who aren’t truck nerds, 90’s to mid 2000’s Dodge Ram 2500 and 3500 trucks have notoriously poor suspension with factory rides similar to what early settlers must experienced on wagon trains.
Don’s work on the platform takes the trucks from zero to hero. His rigs are able to handle the rigors of off-road races like the Baja 500 and 1000 as they run support for the trophy truck teams. The suspension systems also make the trucks a whole lot more fun for the average consumer, creating a truck that can tow a trailer to the desert and then pound whoops and trails. He’s also expanded his suspension design and tuning knowledge into the Chevy 1500 platform, Ram 1500 platform and is even dabbling with Mercedes Sprinter vans. Don is never the type to sit idle.
Like most of us gear heads, Don’s interests don’t just stop at 4-wheeled vehicles. His passion for all things fast and mechanical eventually led him to mountain bikes, and he’s become a staple of the Bend, Oregon riding scene where he lives. Of course, someone like Don can only ride bikes for so long without applying his restless imagination towards their improvement. He began by machining his own stems, but quickly turned his attention towards bigger endeavors.
A long time fan of Thuren Fabrications’ products, I’ve always been intrigued with what Don was up to. To my surprise a few months ago, he posted a photo on his Instagram with some steel tubing in a jig that I knew wasn’t meant for a truck. A week later, he was proudly displaying his first mountain bike. It was a hand welded steel frame like nothing I had ever seen. When I found myself in Bend, Oregon later that summer, I knew I had to make the time to go over and meet Don for the first time.
Years of studying off-road vehicle suspension, fabricating his own and pushing them to the absolute limits in the desert played an undeniable part in Don’s design. A true single pivot, Don’s main goal with his bike is to keep everything as simple and reliable as possible. While the mantra of bike consumers and brands alike seems to be that more complicated suspension designs are somehow superior, the off-road world is entirely the opposite.
In desert racing, simple is always better. Out in the desert, more pivots and linkages simply result in more possible failure points and areas of maintenance. If the same performance can be achieved with a cleverly implemented single pivot instead of 6, then the choice is clear. Don is of the same mentality, saying that he “Got the inspiration for the rear suspension design from a trophy truck rear lower link. That is naturally where my brain went while adapting this design to the rear suspension on a bicycle.” Terrain Control bikes was born.
To draw a parallel, the design is reminiscent of an old Santa Cruz Bullit with an elevated chain stay and large threaded BB pivot. However, unlike the old Bullit, Don designed the bike’s kinematics carefully to both pedal and descend. He claims it does both exceptionally well, without the typical pitfalls of a standard single pivot. The more power is applied to the pedals, the more the bike lifts out of the travel and resists squat and bob.
Geometry for the carbon version is very slack and long for the trail bike category that Don intends the bike to fall into. With 140mm of rear wheel travel and 160mm up front, the over-forked bike will surely make use of it’s 63.6 degree head angle. Reach sits at 470mm for a size large frame with a low bottom bracket height of 34cm (13.38”).
A Sneak Peak
Though the steel prototype weighed upwards of 50 pounds, you’d never know it unless you tried to pick the bike up. Even when bunny hopping, the bike still maintains lots of pop despite the weight thanks to Don’s understanding of suspension kinematics and damper tuning. Though our little test ride was just in a parking lot and a trail head, it’s definitely something different. Don is undeniably onto something with whatever magic he worked in the suspension.
Despite having 29” wheels, the rear end is short with a 413mm chain stay length. It employs a long radius arc swing-arm, which keeps axle path more predictable to counter the normal high-speed drawbacks of the short chainstay. Beyond that, Don is staying tight lipped until the patent is final and the carbon prototypes are built, which should be pretty soon. We couldn’t help but squish the suspension and wonder though.
As Don works to open a new, expanded facility in Bend for Thuren Fabrication, he’ll also have plenty of room in the warehouse. The plan is to launch the bike to the public under the brand name, Terrain Control when it’s ready. Safe to say we’re excited to throw a leg over the carbon version when it’s ready in a few months.
Be sure to leave Don some feedback in the comment section.
Below is the geometry for the first carbon frame that will be tested:
Wheel Size: 29 inch
Fork Travel: 160mm
Rear Travel: 140mm
Head Tube Angle: 63.6
Chainstay Length: 413mm
BB Height: 340mm
Effective ST Angle: 77.5
Seatpost Dia: 34.9mm
Seat Tube Length: 440mm
Crank (Suggested): 165mm
Bottom Bracket: PF92
Rear Axle: Boost 12x148mm
To learn more, visit Terraincontrol.com