Cassette Lockring Tool with 12mm Guide

Thru-axle hubs solved the quick-release stiffness problem and brought a new one with them: cassette removal got harder. A bare lockring tool slips out of the splines under load, and the old quick-release-skewer trick; running the QR back through the tool to anchor it; doesn't work on a hub that doesn't take a QR. The 1670.9/4 is the lockring tool sized for the way modern hubs are built: a Shimano/SRAM HG-pattern socket with a 12 mm centering guide that locates against the thru-axle bore itself.

The guide is the spec. Most current MTB hubs run 12 mm thru-axles, and most current road, gravel, adventure, and CX hubs do too. The 12 mm guide pin slides directly into the hub's thru-axle channel, planting the tool against the wheel without an external axle or skewer holding it down. The splines stay seated through the lockring break-free, the tool can't walk out under load, and the cassette comes off without rounding the lockring's engagement.

For QR-skewered hubs, the Shimano/SRAM Cassette Lockring Tool 1670.5/4 covers the same lockring pattern at a lower price point; that tool relies on the QR skewer for retention. The 1670.9/4 is specifically the version for the thru-axle hub population.

How to use it

Remove the wheel and thread out the thru-axle if it's still in the hub. Slide the 1670.9/4's 12 mm guide pin into the hub's thru-axle bore from the cassette side, seating the 12-spline socket into the lockring. Hold the cassette still with a chain whip or Cassette Wrench on the larger cogs. With a 21 mm wrench or 1/2" ratchet on the back of the tool, turn the lockring counter-clockwise. The guide pin stays in the bore through the full extraction; reverse the steps to reinstall and torque the lockring to spec.

Compatibility

• Shimano HG cassettes, 7- through 12-speed
• SRAM HG cassettes (XD and XDR included)
• Microshift and Sunrace cassettes using the Shimano HG lockring pattern
• 12 mm thru-axle hubs (the 12 mm guide is the spec; won't seat in 15 mm or 20 mm hubs)
• Not for Campagnolo (use 1670.4/4)

Specs

• 12-spline Shimano/SRAM HG lockring pattern
• 12 mm centering guide for thru-axle hubs
• 21 mm hex wrench flat
• 1/2" square drive socket on the opposite face
• 75 mm overall, 122 g
• Article number: 1670.9/4

Built in Zreče, Slovenia

Unior has been forging hand tools in Zreče since 1919, and sponsors professional road and mountain-bike race teams. The 1670.9/4's design choice; sizing the guide pin to the thru-axle standard rather than to the lockring's central bore; is what makes it work without a removable axle. A few cassette tools on the market still expect a QR skewer to do the retention work, which leaves them awkward to use on the bikes most workshops see now. The 1670.9/4 is built for the bikes coming in this season, not last decade's.

Pro tip from our mechanics

The 12 mm guide doesn't replace the chain whip; you still need something holding the cassette while the lockring turns. The Multispeed Chainwhip 1660/2DP-US is the workshop default; the Cassette Wrench (11/12t) is the chain-free alternative when you've got cassettes with the right small-cog size. For SRAM AXS X-Range cassettes with 10-tooth small cogs, neither chain whip nor 11/12t wrench fits; you need the X-Range-specific wrench. The cassette-replacement workflow details tool pairing per drivetrain: When and how to replace your cassette →

FAQ

Will this fit my thru-axle wheel? It's built for rear hubs with a 12 mm thru-axle bore — the 11.9 mm guide pin seats directly in the axle channel, which covers most current road, gravel, and mountain rear ends. Quick-release hubs don't need the pin: use the 1670.5/4, which anchors with the QR skewer instead.

Which cassette lockrings does it drive? The 12-spline socket drives Shimano and SRAM HG-pattern lockrings, 7- through 12-speed, and SRAM XD and XDR cassette lockrings share the same spline interface. Campagnolo lockrings are a different pattern — that's the 1670.4/4.

What wrench does it take? Either end works: 21 mm hex flats for an open-end wrench, or the 1/2-inch square socket in the back for a ratchet, breaker bar, or torque wrench. Cassette lockrings are stamped for 40 N·m, so a torque wrench on the square drive is the clean way to finish an install.

Do I still need a chain whip? Yes, for removal — the freehub spins freely in the unthreading direction, so something has to hold the cassette while the lockring breaks loose. The Multispeed Chainwhip 1660/2DP-US is the usual pairing; the Cassette Wrench is the chain-free option when the small cog is an 11 or 12-tooth.