12-Speed Gear Calculator | Rollout & Speed (SRAM/Shimano/ROTOR)

Chainring curves — X: sprocket (9→38), Y: Rollout (m)

Assumptions: 700×25C wheel (circumference 2.105 m). Rollout = 2.105 × (chainring / sprocket). Up to 4 curves — A (big/small) and B (big/small) — connecting points of the same chainring only. Untick a transmission to hide its curves.

Transmission A
Crankset
Cassette
Transmission B
Crankset
Cassette
A · big ring
A · small ring
B · big ring
B · small ring

Focus on 5 ROTOR products designed to upgrade Shimano & SRAM drivetrains

These ROTOR components fill the gaps left by factory groupsets — lighter, smarter gearing with tailored combinations. Compare them using the gear calculator above, then pick your perfect setup.

ROTOR UNO 12-speed Cassette 11-36 – lightweight alternative to Shimano 12s 105/GRX

ROTOR UNO 12s Cassette • 11–36

Lightweight Alternative spacing Climbing

Compatible with Shimano 12-speed derailleurs (105/GRX long cage). Offers a huge weight saving vs. stock cassettes and a more progressive 11–36 range for smooth cadence on steep climbs.

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Tip: compare 11–34 vs 11–36 in the calculator to see your cadence impact.

ROTOR chainrings for Shimano 8100/9200 – 50/34, 52/36, 53/39, 54/39

ROTOR Chainrings • Shimano 8100 / 9200

Direct replacement Stiff & precise Wide options

Keep your Shimano crankset and upgrade to the right chainring combination: 50/34, 52/36, 53/39, 54/39… Ideal if your bike came with gearing that doesn’t fit your terrain or cadence.

  • Refine cadence for flat & hilly routes
  • Pair with 11–30 or 11–34 for smoother transitions
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Use the calculator above to estimate the gain before ordering.

ROTOR Aldhu Carbon 48/31 – 538 g, lightweight and compact gearing

Aldhu Carbon DirectMount • 48/31

~538 g −150 to −200 g Climbing

At just ~538 g, this crankset saves 150–200 g compared to Shimano while providing smaller gears. Perfect for riders seeking smoother cadence and faster climbing on long ascents.

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Ideal if your cadence drops below 65–70 rpm on steep gradients.

ROTOR Aldhu Carbon AERO crankset – aerodynamic chainrings 54/42 to 58/44 for high speed

Aldhu Carbon AERO • 54/42 → 58/44

Aero design High speed Time trial / triathlon

Built for pure speed — 54/42 to 58/44 chainrings for sustained 50 km/h+ efforts in peloton or tailwind conditions. Ultra-stiff carbon arms, aerodynamic design, no weight penalty.

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Best paired with 10–33 or 11–30 to minimize cadence gaps at high speed.

ROTOR Vegast Inspider 2.0 – dual power measurement, multiple chainring options 50/34 to 54/42

Vegast + Inspider 2.0 • Dual Power

Dual L/R 1.5% 50/34 → 54/42 165 mm option

For a price close to dual power pedals, get a full crankset with integrated dual power measurement. Wide compatibility (50/34 to 54/42) and crank lengths including 165 mm.

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Compare your target power zones and cadence directly with the calculator above.

Need a personalized setup (cadence, terrain, goals)? Contact us — fast reply in English or French.