Here's a super cool tool made right here in Bend, OR. The Crombie Tool is a cassette lockring tool that fits OVER most QR skewers. Brilliant. The Abbey Bike Works Crombie Tool makes for easy cassette changes. This is the single sided versionl with an 8.5” long, 3/8" diameter solid handle. It has a deep Shimano spline. We don't know why any shop or self respecting mechanic wouldn't have one of these in their tool chest.