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 24 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
• 24 mm hex wrench flat
• 1/2" square drive socket on the opposite face
• Trivalent chrome plated to ISO 1456:2009
• Article number: 1670.9/4

Built in Zreče, Slovenia

Unior has been forging hand tools in Zreče since 1919, and is the official technical partner of multiple World Tour and downhill 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 →