R21 UltraMOZA R21 Ultra — direct drive wheel base: 21 Nm sustained torque, 21-bit encoder, 360 W

A wheel you hold, not a wheel you correct

The MOZA R21 Ultra is a direct drive wheel base for drivers who are past experimenting: 21 Nm of sustained torque reproduces the loads of a real race car rather than a scaled-down version of them. Through a fast GT3 corner the wheel resists hard enough that you steer with your shoulders, not your wrists — which is exactly what this tier is bought for. The torque comes from a new-generation motor wound with flat wire and with cogging reduced to essentially nothing: rotation stays smooth at low speed, with no steps or ripple. A 21-bit magnetic encoder reads position — 2,097,152 points per revolution — so both fine surface texture and the moment grip lets go reach your hands. Rated power is 360 W, 110–220 V AC is converted to 36 V DC, and USB polling runs at 1000 Hz. iRacing has a 360 Hz mode, and the upgraded intelligent thermal management keeps output steady through multi-hour stints. The body is a one-piece aluminium alloy shell with a plastic rear cover, measuring 248.8 × 140 × 135 mm and weighing 9 kg. It mounts from the bottom, the front or the side, with an optional adjustable bracket available — but at 21 Nm the base wants a stiff profile rig, not a desk. Dedicated ports for pedals, dash, shifter, handbrake and an emergency stop switch sit at the rear, and two RGB strips run along the top for telemetry. The platform is PC (Windows). The wheel, pedals and mounting hardware are bought separately.

1. 01

   21 Nm is real-car effort

   On entry and mid-tier bases, where torque typically sits between 3 and 17 Nm, a simulator shows you what the car is doing. At 21 Nm it starts loading you with it: through a fast GT3 corner the wheel has to be held, not corrected, and the fatigue after an hour is part of the race. The torque is sustained — the base holds it continuously instead of delivering bursts — so the wheel behaves the same on the last lap as on the first.

2. 02

   A flat-wire motor with zero cogging

   Flat wire packs into the slots tighter than round wire, so the motor makes more torque for the same size. More importantly the design has no cogging: at low wheel speed there are no magnetic steps, just even rotation. You notice it in the pit lane, in a hairpin, and any time the wheel is barely moving while you hunt for the last of the grip.

3. 03

   A 21-bit encoder: detail on top of big forces

   Big torque is useless if it drowns the small stuff. The 21-bit magnetic encoder resolves 2,097,152 positions per revolution and USB polling runs at 1000 Hz, so on top of a heavy wheel you still feel the kerb, the tarmac seam and the moment the front axle starts to drift. iRacing adds a 360 Hz update mode.

4. 04

   Heat under control over a long race

   The one-piece aluminium body works as a heatsink, while the upgraded temperature control watches the heat and manages output so the base does not drop into protection mid-stint. For endurance racing that matters more than peak figures: the force on lap one hundred has to match lap one, or you end up re-tuning during the race.

5. 05

   Three mounting faces — and a stiff rig

   The base bolts from the bottom, the front or the side, with an optional adjustable bracket, so it can sit at the right angle even in a tight cockpit. Physics still applies, though: 9 kg and 21 Nm need an aluminium-profile rig or a genuinely rigid stand — on an ordinary desk that torque will rock the whole setup. Budget for the mount from the start.