Rear Derailleurs

❓1. How to check derailleur compatibility with my drivetrain?

• Number of speeds: the derailleur must match exactly (10, 11, 12 speeds).
  
• Shifter type :
  SRAM ↔ works with SRAM shifter.
  Shimano ↔ works with Shimano shifter.
  Both systems are generally not compatible (different pull ratio).
  
  
• Derailleur capacity: must cover the size of the largest sprocket (e.g. 50/51/52 teeth in 12 speeds).
  
• Cage :
  Short (SS) → cassette with narrow range (road, urban).
  Medium (GS) → MTB XC / Trail.
  Long (SGS) → large cassettes (e.g. 10–51).
  
  
• Mounting: standard hanger vs cage type UDH (SRAM Transmission AXS).

❓2. How to choose based on my riding style (XC, trail, enduro, DH)?

• XC / Marathon: Light weight, medium cage, precise and fast operation. Efficiency-oriented models (e.g. Shimano XT / SRAM GX).
  
• Trail / All-Mountain: Robustness + wide gear range.
  Derailleurs with high-performance clutch (anti-shock/anti-chain slap).
  
• Enduro: Reinforced derailleur, rigid cage, anti-breakage protection. Powerful clutch to prevent noise and chain drops.
  
• DH: Derailleur short cage, ultra resistant, very specific cassette. Priority on chain retention rather than gear range.

❓3. Which technologies and options should you prioritise?

• Clutch: essential for MTB → reduces chain drops and noise.
  
• Mechanical vs electronic choice (AXS) :
  Mechanical → reliable, economical, easy to maintain.
  Electronic (SRAM AXS) → exceptional precision, self-adjustment, cable-free, but more expensive.
  
• Profiled upper pulley: improves precision on larger sprockets.
  
• Direct mount (UDH Transmission): Stiffer, more precise, designed for modern compatible frames.
  Highly resistant to impacts.

❓4. What materials and which range level to choose?

• Aluminium: excellent weight-to-strength ratio.
  
• Steel: very robust, ideal for tight budgets or intensive use.
  
• Carbon / composite: lightweight, often high-end, good stiffness.
  
• Bearings :
  Plain bushings → economical.
  Sealed bearings → better durability and smoothness.
  
• Moving up the range = + precision, + stiffness, + silence, + durability.

Want to know more? Check out our buying guide:

How to choose your MTB rear derailleur

How to properly adjust your MTB rear derailleur