Peak vs Sustained Torque: What Direct Drive Wheelbase Ratings Actually Mean

Peak torque is the most torque a direct drive wheelbase can produce for a brief moment. Sustained torque is the torque it can keep producing continuously without overheating. Peak figures cover short spikes such as kerb strikes and sudden corrections; sustained figures decide what the base can hold corner after corner over a long session. The same number in Nm therefore describes two different capabilities, and a torque figure on a spec sheet only becomes comparable once you know which one you are reading.

What Is Peak Torque in a Direct Drive Wheelbase?

Three constraints set a motor's peak torque:

Supply limit. The drive electronics can only deliver so much current and the power supply so much power, and when the wheel spins fast, the voltage the motor itself generates leaves less room for current.

Magnetic saturation. Past a certain point, extra current adds progressively less torque, so a small torque gain carries a large heat penalty.

Thermal limit. Maximum current heats the windings quickly, so this level of output is only available in short bursts before the system has to back down.

In force feedback, those bursts are the abrupt events: a harsh kerb, a heavy suspension impact, a sudden correction to catch a sliding car. How long a base can stay at its peak depends on its design, so a peak figure on its own says little about what the base can hold.

What Is Sustained (Continuous) Torque?

Sustained torque, also called continuous torque, is a thermal rating: the torque a base can keep producing without its motor or drive electronics exceeding their temperature limits. The figure only holds for given conditions, such as the surrounding temperature and the cooling available. Copper loss rises with the square of the current, and the current is what makes the torque, so doubling the torque roughly quadruples the heat. The sustained rating is the highest torque at which that heat is shed as fast as it is produced without passing the limit. Hold more than that for long enough and thermal protection reduces the current, so the force feedback gets lighter. In a warmer room, the same base can hold less torque continuously.

MOZA rates its Ultra Series in sustained torque, from the MOZA R16 Ultra at 16 Nm through the MOZA R21 Ultra at 21 Nm to the MOZA R25 Ultra at 25 Nm. A flat-wire motor sits at the core of all three. It produces less heat at a given torque than a comparable round-wire motor and dissipates it more effectively (see Flat-Wire Motors…