This structure is particularly well suited to high-pivot designs and provides several important advantages :

ㆍIncreased rotational speeddoubles the engagement speed between the pawls and the internal gear teeth, effectively reducing pedal free-play and engagement lag.

ㆍBecause the torque transmitted to the main shaft is halved, overall durability is improved.
This allows the gear width to be significantly reduced, resulting in meaningful weight savings.
Alternatively, it enables the use of aluminum for the middle shaftand titanium for the gears. (low-strength titanium processed by CNC machining)

ㆍThe design allows the elimination of oil seals, which are a common source of drivetrain losses.
The only potential leakage point is the right-side bearing of the middle shaft. However, a dedicated cover surrounding the pedal-side gear prevents even minor oil seepage from escaping to the outside.

ㆍAlthough the main shaft contains six gears, which may suggest a 6-speed system, the ATH12 incorporates an internal planetary gear set.
When power is transmitted through the planetary reduction, gears 1–6are generated.

When power bypasses the planetary stage and flows directly from the main shaft to the output shaft, gears 7–12are produced.

This architecture achieves a high gear count without adding extra shafts, gears, or bearings, resulting in a structurally efficient and mechanically optimized gearbox designed for downhill MTB performance.