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Chain Seal Types

An Introduction to Chain Seals

A chain seal helps maintain lubrication as well restrict dirt from entering between the chains inner and outer plates.

There are many chain manufacturers in the motorcycle industry but most (including some Japanese manufacturers) only offer a single type of sealing ring, using a “one type fits all approach” which is used on all their drive chains. This can be inefficient depending on the intended use. Different types of seals for different applications maximises efficiency and performance

Both CZ Chains and RK Chains offer different types of chain seals.

Merit Of A Sealed Chain

  • Minimum 3 times longer chain life than Non-sealed Chain
  • Does not elongate until the end, does not cause pitch error during operation
  • Efficient Power Transmission = Minimum Loss of Horse Power
  • Able to prevent debris from entering the chain = Maintain performance in muddy or rough road conditions

A summary of each chain seal type

  • NS - Non-sealed
  • O - Standard O-Ring seal
  • RX / Active (X-Ring) - Double barrier, Better Chain Life
  • XW (Preimum X-Ring) - Triple Barrier, Best Chain Life
  • U - Ultra Thin (0.8mm), Lightest Chain Weight
  • UW - Triple Barrier, Improved Chain Life Over "U"

The graph shows how each seal type across the RK range differs in terms of elongation over time


  • The first and standard type of chain seal
  • Simple and robust design
  • Cheaper than X-Ring designs
  • Used in GSV chains

RX / Active Ring (X-Ring)

  • Improved seal technology over O-ring seal
  • RX ring Developed in 1978
  • RX-ring 'X' shaped seal has 2 times stronger ware life than O-ring chains
  • RX-ring has one lubrication pool and 2 contact lips, improving the chain life and lowering friction
  • Used in XSO chains

XW Ring (Premium X-Ring)

  • Developed for Paris Dakar in 1985
  • Ultimate sealing performance to endure desert sand
  • RK's unique technology
  • Used in EXW & ZXW Chains

UW Ring

  • Developed for on-road racing in 1999
  • Same thickness as U-ring with increased grease pool
  • Developed with Suzuka 8H top teams
  • Team Honda Seven Stars, won with 520UWR at Suzuka 8H in 2004
  • Used in MXU & UWR

U Ring

  • Due to weight merit, developed On Road Racing Chain
  • Dominating Suzuka 8H since 1997
  • Contribute HRC Champion for GP 250cc class at 19997 and 2001
  • Used in HRU & TRU Chains