Which Retroflex system is suitable for me? Knee bend under 60 degrees Retroflex RX2 or RX3 Knee bend over 60 degrees Retroflex RX2 or RX3 Recreational trails and road Retroflex RX2, RX3 or Comfort cranks Rehab following surgery Retroflex RX2 (Exercise Bike or Static Trainer) Sport Road Retroflex RX3 or Custom cranks MTB off road Retroflex RX3 or Custom crank. (Retroflex RX3 is not suitable for jumps or stunts) Touring Retroflex RX2, RX3 or Comfort cranks jim.mills2020-12-18T13:47:45+00:00