Sigeyi Power Meter (AX315): Carbon-Crank Power for $400

Sigeyi (often transliterated as “Segeyi” or “Sigeyi”) is the third Chinese power-meter brand to crack the WorldTour in 2026, alongside Magene and Elilee. The brand has been making carbon cranks since 2018, but the 2026 AX315 dual-sided carbon power crankset is the first product positioned at the European aftermarket.

The pitch is simple: a real carbon-fiber crank with dual-sided power measurement, under $400. After six weeks of testing, the reality is more nuanced.

Key Specifications

• Dual-sided carbon-fiber crankset
• Claimed accuracy ±1.5%
• ANT+ and Bluetooth LE
• Rechargeable 200-hour battery (USB-C)
• IPX7 water resistance
• Available in 170 / 172.5 / 175 mm crank lengths
• Shimano 4-bolt 110 BCD chainring mount
• BSA / BB86 bottom bracket compatibility
• $399 USD MSRP for the crankset (chainrings extra)

Build & Design

The AX315 looks like a cross between a Quarq DZero and a Shimano Ultegra R8100. The carbon finish is matte, the spindle is exposed steel, and the strain gauges live inside the spider area. The non-drive-side crank has a small status LED and a USB-C charging port hidden under a screw-down cover.

At 640g for the crankset (excluding chainrings and BB), the AX315 is competitive with the Ultegra R8100 (680g for the non-power version) and lighter than the Quarq DZero (~750g). It feels solid in hand, with no creaks or play during the test period.

Real-world Testing

Six weeks of structured training and a 300km mixed-surface ride gave a clear picture. Pairing was instantaneous with every head unit tested. Battery life tracked the 200-hour claim with about 5% margin.

Side-by-side against a Quarq DZero on the same bike, the AX315 was within 3-4 watts at threshold and within 1-2 watts on steady-state work. On 5-second sprints it was within 6-7 watts, slightly worse than the Assioma DUO (within 5 watts) but acceptable. Left-right balance accuracy tracked the DZero within 1.5%, which is more than good enough for training.

Temperature compensation worked across a 5°C to 30°C range without recalibration. Cold-weather performance (around -2°C) was within 1% of the DZero, slightly worse but acceptable.

Pros

• Sub-$400 for a carbon dual-sided crankset
• Rechargeable 200-hour battery
• Competitive weight at 640g
• Wide BB compatibility (BSA / BB86)
• Solid build quality with no creaks
• Used by a 2026 WorldTour team (Bahrain-Victorious)

Cons

• Chainrings are not included (~$90 extra for Shimano 105)
• Sprint accuracy is slightly worse than Assioma or Quarq
• Sigeyi app is functional but lacks advanced analytics
• No T47 or PF30 BB compatibility
• Long-term durability data limited (brand only 8 years old)

Verdict

The Sigeyi AX315 is the best carbon-crank power meter in the sub-$400 bracket. It is the right choice for riders building a new bike who want a carbon crank and dual-sided power in one purchase. Riders with existing Shimano cranks should consider the Magene P515 ($279, similar accuracy) instead. Riders who want the absolute best sprint accuracy should still consider the Assioma DUO or Quarq DZero. For everyone else, the AX315 is a serious option in 2026.