The State Bicycle Company Thunderbird Frame:
The State Bicycle Company Thunderbird is a dedicated single-speed cyclocross bike, constructed of 6061 aluminum tubes tig welded in Taiwan and finished with attractive paint and graphics. The Thunderbird uniquely has a 46mm internal diameter 68mm wide BB, the same dimensions as a PF30, but with set screws for the eccentric BB. In our experience, this works better than a wedge or pinch bolt clamp style system for securing the eccentric to maintain chain tension. That bottom bracket is set high with a 54mm drop.
Each of the round tube diameters is large, with a huge down tube as the foundation. The head tube is tapered externally to accommodate a tapered steerer fork. The fork is painted to match with carbon blades attached to an aluminum steerer and crown, with aluminum fork ends.
Ample tire clearance with 33mm tire in place. Note the eccentric BB set screws. © Clifford Lee / Cyclocross Magazine
Our 56mm frame had 42.5cm chainstays (though listed as 42.0), with 610mm front center that equals out to 102.6mm for the total wheelbase. The heat tube angle is listed as 71.5 degrees, which contributes to the slightly long front center.
Provisions exist to convert the Thunderbird to a geared machine. The frame has top tube cable stops for derailleur cables with a cable stop on the back of the seat tube for the front changer, and rear derailleur cable stops along the right chainstay for a traditional ’cross setup. The rear dropout faces can be replaced with one that includes a derailleur hanger, as ours came equipped with.