1) Friction: what the test shows… and the golden rule

The Velo/Outside bench test (250 W / 95 rpm) compares a 1x (48T + 10-33 cassette) with a 2x (53/39 + 11-34). Result: the 2x records lower losses in each optimal ratio (average ≈9.45 W) than the 1x (≈12.24 W), with a marked penalty as you approach the 10-tooth cog (e.g., 48×10 ≈ +6 W vs 53×11). This reflects a simple rule: at the same rollout, “big ring + larger rear cog (mid-cassette)” is more efficient than “small ring + small rear cog.”

2) Legal context: SRAM challenges, the UCI responds

SRAM brought a complaint to the Belgian Competition Authority regarding the Maximum Gear Ratio Test Protocol (cap 10.46 m, equivalent to 54×11), trialed at the Tour of Guangxi and potentially generalized in 2026. The UCI issued an official response: stakeholder consultation, a safety-driven approach, and majority rider support for the trial. Read the UCI press release (EN).

3) Tactics: what does 54×10 / 55×10 do in a race?

On finales with a downhill dip, the 10-tooth can be used to tighten the run-in: the bunch lines out, rivals must move into the wind to regain positions, and you arrive at the sprint with fewer opponents. The advantage becomes clear mainly above ~70–80 km/h — below that, 54×11 or 55×11 already cover most needs.

4) Cadence → speed (top gears)

Assumptions: same rollout as the UCI reference (54×11 = 10.46 m). Comparison SRAM AXS 54×10 (10-33 cassette) vs Shimano 55×11 (11-34 cassette) + reference 54×11 (= UCI cap). Speeds rounded.

Takeaway: the 54×10 advantage shows mainly at very high speed (≥70–80 km/h). The trade-off is that the 10-tooth is less efficient (friction) than an 11 at a similar ratio.

5) Note for sportive riders (real-world use)

Many amateurs like AXS because it’s compact, light and “plug-and-play”. A lot of riders cruise on 48×19 / 48×21: that’s the middle of the cassette, where losses are minimal—and a very common gear. The 10-tooth is really for very fast tailwind/descending scenarios.

6) 2026: two plausible scenarios

1. The UCI loses (no convincing “safety ↔ gearing” link) → status quo, 54×10 stays legal.
2. The UCI wins → 10.46 m cap becomes universal. Likely SRAM response: supply teams with 11-tooth start cassettes to preserve top speed, rather than forcing smaller rings on 10-33. The brand message would otherwise be awkward vs consumer bikes mostly on 48×35.