Favero Assioma PRO MX: 5,000 km Later, Our New SPD Baseline

The Assioma PRO MX is Favero’s SPD pedal in the Pro spindle line. Internally it shares the same electronics package as the PRO RS and PRO RL, with a slightly taller stack height and a different pedal body. We have been riding the PRO MX since April 2023 — over 5,000 km across both a gravel bike and a mountain bike, in every condition from dry summer dust to wet winter mud. The data has been consistently clean, and we now use the PRO MX as our SPD baseline for head-to-head testing.

TL;DR

The PRO MX is the lightest SPD power-meter pedal on the market, with the same ±1% accuracy and IAV cycling dynamics as the rest of the Pro line. After 5,000 km of mixed gravel and mountain bike use, including rain, mud, and pressure-washing, the pedals have shown no squeaks, no seal failures, and no calibration drift. We are now using the PRO MX as our new SPD baseline for head-to-head testing.

Unboxing & Design

Same Favero packaging as the rest of the Pro line. Inside the box: pedals, a magnetic charge pod for each side, a micro-USB cable, a small bag of Shimano SM-SH51 SPD cleats, mounting hardware, four pedal washers for carbon-crank installations, and the greasing tool. The pedals are clearly marked left / right on the platform, with a small notch on the left-hand spindle to confirm the orientation.

The PRO MX uses the same sealed-cartridge Pro spindle as the PRO RS and PRO RL, with all electronics, battery, and sensors contained inside the spindle body. The pedal body itself is Favero’s own SPD-compatible design, manufactured in Italy. Two needle-roller bearings per pedal, 53.2 mm Q-factor (we measured it ourselves — it is not in the official spec sheet), and 11.2 mm stack height. The replacement pedal body is €49 + tax per side, so swapping between SPD and SPD-SL bodies (using the PRO RS or PRO RL pedal bodies on the same spindle) is realistic and cheap.

Setup & Installation

Installation requires a 15 mm open-ended wrench and 40 Nm of torque on the spindle threads. The Favero app walks through activation, firmware check, and zero-offset calibration on first install. For carbon cranks, the included pedal washers are required — not optional. We recommend a thin smear of grease on the threads, both for easier removal at the first re-grease and to avoid creaks.

After a firmware update, the app will step you through a manual zero-offset calibration. This is required, not optional — the pedals will not report power until they are calibrated. Activation is also required; pedals ship in travel mode and will report 0 W until activated. The whole setup process takes about 5 minutes if you have the app installed and the firmware is current.

Real-World Data

We have run the PRO MX on the test bench for over a year now — our reference dataset is 70 individual files. We will summarise the headline findings.

Indoor ERG (Direto XR + Quarq AXS + PRO MX): steady-state 183 / 185 / 186 W — within 1% of the Quarq spider. Step test 212 / 215 / 215 W. Sprint into overs-and-unders 223 / 227 / 226 W. Nothing to report on the Pro spindle; the data simply works.

Outdoor mountain bike (PRO MX + power2max NGeco): 8-minute hard effort 333 / 325.9 / 326.9 W. 30/30s overs and unders 240 / 240 W. The data is so clean we could not find anything to dig into.

Outdoor gravel (PRO MX + Quarq AXS): one ~30-minute steady-state at 185 / 186 W. A short section in the middle of the ride showed a 10 W offset, which resolved after a manual zero of the Quarq — the PRO MX was the more stable of the two, with no shift over the full 3h 15 ride.

Crit race (PRO MX + Quarq AXS): steady-state 236 / 239 W on a hilly course, sprint 1,159 / 1,180 W. The PRO MX is slightly more responsive to the spike on sprint start; the Quarq trails by 1–2 W at the peak but catches up in the average.

Long-Term Use

Over 5,000 km, the PRO MX has been faultless. No squeaks from the pedal bodies or the cleats — this is a real achievement on an SPD pedal, where shoe / pedal interface squeaks are common. No seal failures, no drift in the calibration, no impact damage. The pedals survived a 20% grade climb in heavy rain without issue. We have not had to re-grease within the test period, and the pedal bodies showed no visible play at 5,000 km.

The IAV cycling dynamics — power phase, peak power phase, platform center offset, torque effectiveness, pedal smoothness, rider position — are reported in real time on the Favero app’s live tab. Peak power phase responds as expected to gradient changes: pointing up on a 3% climb, dropping to the floor when out of the saddle. Platform center offset is the most useful metric on a mountain bike — if your PCO is consistently off-centre, your cleat position needs adjusting.

Competitor Comparison

SRAM AXS power meter spiders (€550 + crank) are the most direct competitor in the mountain bike space. They are accurate but lack left/right balance, and the spindle-based design has a slightly taller stack height than the PRO MX. Quarq DZero (€600 + crank) is the long-standing reference; the data quality is comparable but Quarq is heavier and more expensive. Garmin Rally XC (€1,099) is the SPD alternative in the Rally range; it is heavier than the PRO MX and the stack height is taller. The PRO MX is the lightest and most accurate SPD pedal power meter we have measured.

Final Verdict

The PRO MX sets a new standard for SPD power-meter pedals. Light, accurate, IP67, no squeaks, and now our new SPD baseline. The price (€714 + tax) is competitive with the Assioma DUO but you get the full IAV cycling dynamics suite. The only real improvement we would ask for is USB-C charging on the spindle end instead of the magnetic micro-USB adapter. We rate the PRO MX a strong buy.