AI quick summary
- Both are accurate within normal training tolerances; the gap is smaller than forum arguments suggest.
- Pick by ecosystem: deep Garmin setup → Rally; everything else → Assioma.
- Cleat compatibility is the practical tiebreaker for Shimano SPD-SL riders.
/ 01
The short answer
If you run a Garmin Edge and want zero friction, Rally. Otherwise, Assioma gives you comparable accuracy and battery for less money. The detail below explains when that flips.
/ 02
Price and what's in the box
Both sit in the upper-$400-to-$600 range for single-sided versions and higher for dual; Assioma is usually the cheaper of the two at a given sidedness. Street prices move with sales and model years, so check current pricing before buying. In the box you get the pedals, chargers, and cleats — Rally's cleat variant (Look / Shimano SPD-SL / SPD) depends on the SKU you pick.
/ 03
Accuracy — the part everyone argues about
Both advertise ±1% accuracy, and long-term independent testing (DCRainmaker, GPLama) treats them as effectively equivalent for training purposes. The real-world gap between them is smaller than forum arguments suggest — for setting and pacing zones, the difference is noise, not signal.
/ 04
Install and swapping between bikes
Both install like normal pedals with a torque wrench and swap between bikes in minutes — that's the whole appeal of pedal-based power. The practical note: use the right torque and a proper pedal wrench or hex interface, and take care not to cross-thread the pedal adapter.
/ 05
Battery and charging
Assioma charges via a magnetic clip without removing the pedals; Rally uses USB charging behind a small cap. Battery life lands roughly in the 50–120 hour range depending on model — weeks of riding for most users. Assioma's magnetic clip is slightly more convenient day-to-day.
/ 06
App and ecosystem
Rally's real advantage is native Garmin Connect — it appears and behaves like first-party hardware. Assioma's app is simpler but does everything a non-Garmin rider needs. If your head unit isn't a Garmin, Assioma's neutrality is a plus, not a minus.
/ 07
Cleat compatibility
Assioma uses Look. Rally ships in Shimano SPD-SL, Look, or SPD-flat variants. If you're on Shimano SPD-SL, Rally saves you a cleat swap — and that alone decides it for some riders.
/ 08
Who should buy which
Assioma: value-focused, multi-bike, non-Garmin households. Rally: Garmin households, Shimano SPD-SL riders, and anyone who wants one ecosystem end to end.