This Specialized patent reveals a dual chain that breaks with everything we knew until now

In the World Cup, there is a bike that has been generating questions for longer than we would like to spend without knowing what happens under its camouflage. This is the prototype of the upcoming Specialized Demo with which the team riders have been competing in DH for several months now. Now, a patent reveals that it could hide a dual chain transmission system with an intermediate axle that breaks with everything we knew until now.

Specialized registers a patent with dual chain and intermediate axle: a system that could redefine many modalities

It has been the guys from Pinkbike who found this patent that could change many things in the future, revealing one of the most interesting developments we have seen in recent years.

The documentation shows an internal arrangement where a secondary chain is responsible for transmitting movement from a gear attached to the crank axle to a first sprocket. From that point, another external gear moves the primary chain that goes to the rear wheel. It is a jackshaft-style architecture (intermediate axle) that physically separates the point where the pedaling force is generated from the position of the main gear that pulls the chain. This independence allows repositioning the traction point without depending on the location of the bottom bracket, something that opens the door to much more precise control over the behavior of the suspension.

The importance of this design lies in the fact that it offers Specialized engineers a kinematic freedom that does not exist in a traditional system. By being able to choose where to place the main gear without being constrained by the cranks, it becomes possible to adjust decisive factors such as antisquat, pedal kickback, or the trajectory of the rear axle at will.

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The patent itself insists that this arrangement can increase the efficiency of the primary chain, allow for a more rearward axle movement, and reduce overall system wear, something especially relevant in a downhill bike subjected to high loads and long travel. Additionally, separating the transmission into two phases provides the extra benefit that the chainring can be placed higher, improving ground clearance and decreasing the likelihood of impacts.

Another striking aspect is that this architecture allows for varying the gear ratio without altering the kinematics of the suspension. In a conventional setup, changing the size of the chainring modifies the position of the chain and affects the instantaneous center. Here, by only varying the size of the internal gears, the development can change without compromising how the suspension works. This opens up possibilities that were practically impossible until now in a DH bike seeking specific combinations of behavior and development.

The pulley visible on the outside, located concentrically to the bottom bracket, does not participate in power transmission. Its function is to "move" the primary chain away from the cranks and improve the attack angle on the main gear to ensure greater retention and prevent skipping. It is a minor detail within the system, but necessary for the system to function cleanly.

Everything indicates that this project is already in a very advanced phase. The patent confirms that Specialized has invested in specific carbon molds for this frame and also indicates that the system could be used in other platforms, such as eBikes.