How long does a Sparx grinding ring last?

A Grinding Ring (Radius Ring or FIRE Ring) will last for 320 cycles. If you're freshening up your blades after every skate, you'll get 50-60 sharpenings (or even more!) per ring and if you're sharpening your skates after every 5-6 hours of ice time, you'll get about 40 sharpenings.

When should I replace my Sparx ring?

If you are freshening up your blades after every skate, 1-2 cycles will usually be enough. If you're sharpening your skates after every 5-6 hours of ice time, you'll typically want to run 4 cycles. If you're changing your radius or have new steel, you will need about 10 cycles.