XPR50 50T Expander Ring

Plenty in stock

Shout about this product!


Upgrade your 11-42T Shimano cassette to a wider ratio with Superstar UK made XPR50 (X-sPander-Ring) upgrade ring. The Shimano specific 50T sprocket has been designed to exactly fit the Shimano XT M8000 and SLX M7000 cassette design. The kit includes a custom made stainless 18T ring to smooth out the ratio curve of your new upgraded cassette. We recommend a long cage rear mech to allow for the chain growth or a aftermarket extension cage (Superstar XPR cage is coming soon):

  • XPR ring installs behind existing cassette 42T sprocket, and swap 17T and 19T sprocket for a CNC machined 18T to smooth ratio curve
  • Shimano XT M8000 specific tooth profiles and shifting points;
  • Precise timing of the shifting points specific to the cassette;
  • CAD optimised structure reducing flex and smoothing shift performance;
  • Anodized Austrian manufactured 7075 T651 aluminium
  • Available in a range of colours
  • Weight: 101g (50T and 18T rings)

Designed and CNC machined from 7075 T651 aluminium in our own facility in the UK. By manufacturing products with the highest quality machinery, we can offer market leading quality for amazing value.


  • Race
  • XC
  • AM
  • Enduro

Tech Specs


  • 50T Shimano - g

Suitable for 11 speed chains only

Shimano version compatible with:
XT (M8000 11-42) - 11spd cassettes
SLX (M7000 11-42) - 11spd cassettes

We do not recommend short/medium cage mechs as they may not have enough chain capacity to cope with large rings and chain growth. You must test at extremes of suspension travel and gear ratio before using, to confirm your installation is safe. X-Long b-tension M4 screw may be needed in case you require more adjustment.


An inside view of the manufacturing process by our technology partner Delcam, who supplies our CAM software for programming the CNC machines:


  • Too Thin

    Posted on 14 December 2017 by A. Crocker

    2 stars
    This expander rings flexes way too much under strain while climbing. The aluminum should be thicker up to the point just below where the chain sits on the ring.