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Small Parts Derailleur

CeramicSpeed OSPW X System

The CeramicSpeed Oversized Pulley Wheel System has been developed for the ultimate obsession with maximum performance and attention to detail that many top competitors possess. The OSPW derailleur cage and pulley wheels are the result of an in-depth development process and have been designed to reduce friction to the greatest extent possible. The oversized 17T pulleys are capable of spinning with as much as 60% faster speeds than stock pulleys, which can help to create the ultimate efficient drivetrain. Some models employ a 13T / 19T upper/lower combination. Testing has demonstrated that at just 2.4 watts of power, energy is being saved in the pulley system. When seconds, and tenths of seconds determine winning, personal bests, and/or age-group dominance, the OSPW system is your best friend.

Those familiar with CeramicSpeed's pulley wheels will do a double take at the sheer minimalism of the OSPW machined aluminum pulleys. Of course the pulley wheels feature the high quality, precision built CeramicSpeed Grade 3 Silicon Nitride balls that possess the best possible surface finish and roundness. The approximate 57 gram (varies by model) OSPW system includes a specially fabricated derailleur cage that has been designed to replace in this case your Shimano 11 speed GRX and RX rear pulley cages (13/19T) used with 2x11 drivetrains with cassettes up to 11-34T. No special installation is required, your remove the stock cage assembly and install the OSPW system exactly as you would the stock cage. This ultra-light, yet stiff and resilient cage is made from carbon fiber and reinforced polymide. Aero testing shows the oversized cage has no negative effects on aerodynamics, so there are no trade-offs inherent in the design. The max cassette range capacity is listed below with each available option.

Concerned about durability or other issues? There are considerations, but not from wear. CeramicSpeed pulleys last 3-5 times as long as most of these top-market derailleur's stock pulleys, which offer great life themselves. If you do travel with your bike in a bike bag, you will want to remove the cage before packing as there is not enough clearance. Regular lubrication of the bearings is required, and CeramicSpeed supplies the correct lube and instructions. We recommend you install a new chain when you install the OSPW, as you will need a longer chain. The upper and lower specific pulleys are directional, so if you remove them, re-install properly.

Top pro cyclists and triathletes can attest to the value of the OSPW system. Whether or not this is the correct upgrade for you is a decision you will have to make. If you are the type that has ceramic upgrades in your wheels and bottom bracket (CeramicSpeed, of course), then you will consider the pulley wheels or OSPW. If saving watts and seconds matter most, go OSPW and feel the freedom of the fastest pulley wheel system developed to date.


  • Oversized ceramic bearing pulley wheels/cage assembly for most of the top road group rear derailleurs
  • Aluminum pulley wheels sculpted to the absolute minimal structure
  • Brand models feature 17/17T, 13/19T , or 15/19T pulley wheels- see list below
  • CeramicSpeed Grade 3 Silicon Nitride balls in tight tolerance steel races
  • Incredible reduction in drivetrain friction and increase in pulley wheel speed
  • Cage constructed from carbon fiber and polymide is stiff and aero
  • Engineered to perfectly replace/upgrade existing rear derailleur cage system
  • No negative impact on shifting performance, compatible up to 11-34 cassette
  • Includes OSPW, bearing-specific lubricant and instructions
  • Pulley wheel colors: Red, Black (not all colors available all types)
  • Options / Cassette range max:
    • GRX/RX 13T/19T for 2x11 set-ups
  • Weight: varies by model
  • Hand assembled in Denmark