Dirt Rag Magazine

Suspension and frame tech on display at NAHBS

By Josh Patterson

Bicycle Fabrications

Hank Matheson of the Bicycle Fabrications is not afraid to push the limits of bicycle design. This year, Matheson had two very interesting prototype downhill bikes on display.

No, this bike’s linkage does not employ old tubes and electrical tape. Bicycle Fabrications is attempting to patent a new multi-link suspension design. They are keeping things under wraps until the patent is pending.

Buried beneath the tubes and tape is a linkage that also allows for 1.5-inches of reward travel in addition to the bike’s 8-inches of vertical travel. The idea is that the 1.5-inches of rearward travel is activated when the bicycle encounters square-edged bumps.

The two DH rigs have slightly different versions of the same linkage. Our educated guess is that the suspension employs an auxiliary shock—perhaps something similar to Kona’s Magic Link, but rather than controlling geometry and suspension travel this shock is used to control the fore-aft axle path.

The bike’s 63-degree headtube angle was not slack enough for Matheson, who prefers to ride with most of his weight over the front wheel. He uses an AngleSet to relax the head angle to 62.5-degrees. He admits his setup is not for everyone and that the rider really has to be pinning before the bike comes into its own.

Matheson’s personal bike features Paragon Machine Work’s sliding dropouts designed for a 12mm thru-axle. The sliders allow Matheson to adjust the bike’s chainstay length from 16.5- to 17.25-inches. Rear spacing in 150mm.

Stinner Frameworks

Aaron Stinner of Stinner Frameworks built this fillet-brazed steel frame for a Denver-based rider looking to tackle to Tour Divide race. The customer’s five-foot-five stature and specific race needs made him an ideal candidate for a custom 29er.

Thoughful touches abound, including sleeved top and downtubes to bolster the very front end stiffness, and internally-routed shift cables running through the downtube.

The stand out feature is the partial seatmast. Full seatmasts can cause shipping and transportation issues. This “half-mast” uses a sleeved seatube with artful cutouts.

 

Note the 142×12 rear end and the internally-routed brake line.

Calfee

It’s hard to miss a big black tandem, especially one as striking as Calfee’s Tetra 29er.

There are few better applications for electronic shifting than tandem bicycles. K-Edge’s “Ki2” electronic shifting kit converts Shimano’s Di2 from a road to mountain/flatbar shifting system.

Much cleaner than Shimano’s Di2 battery, Calfee’s seat tube-mounted battery is housed in the stoker’s seatpost.

Running the timing chain on the drive-side allows the user to spec a much wider range of non tandem-specific components, such as this pair of e*thirteen cranksets.

 

The one-piece, seatpost/stem/stoker bar combo is an impressive, and very time-intensive piece of work, but Calfee can’t take all the credit. The seatpost is an ENVE setback and the handlebar is a 10-degree Ritchey WCS flatbar. They are joined together by a section of carbon tubing wrapped in strips of unidirectional carbon fiber cloth.

So how much does his carbon fiber masterpiece weigh?

 

Calfee was kind enough to humor my request to weight the complete bike.

 

The frame reportedly weights a scant 6.5 pounds. Calfee’s custom carbon tandems frames start at $6,195. This complete bike cost the customer a cool $19,000.

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