As I was riding my rigid ss 29er on some of my favorite trails this past weekend, I was reminded of the value of suspension for increased traction and decreased fatigue. Trek’s IsoSpeed Technology has been slowly, and expectedly, working its way from their Domane endurance road line, through their Boone cyclocross line, and finally to their hardtail mountain line. In April, Velonews spotted IsoSpeed Tech on Trek hardtails at USA Cycling US Cup races (available here: USA Cycling), and BikeRumor reports spy shots of Trek’s new rides from the Nové Město World Cup races (full races: women, men) last weekend.
On October 14, 2014, the USPTO issued US 8,857,841 to Trek for their passive seat tube pivot joint, which is marketed as IsoSpeed Technology.
[T]he non-bonded rigid yet pivotable connection of seat tube 22 with upper frame member 100 allows deflection of seat tube 22 in a vertical plane and in a direction along the longitudinal length of the seat tube 22 so as to allow the frame assembly 12 to provide a limited degree of suspension performance or vertical compliance without altering the orientation of the connection points of any of the frame members relative to one another
The pivotable connection between the seat tube 22 and the upper frame member 100 (i.e., top tube) is shown in an exploded view in FIG. 5:
Trek states that the deflection should be nearly unperceivable during most riding conditions, but even absorption of small bumps by the frame in a mostly unnoticeable manner can greatly improve fatigue resistance and comfort when you’re spending hours in the saddle.