Shimano/SRAM Cassette Lockring Tool

The 1670.5/4 is the basic Shimano/SRAM cassette lockring tool: the 12-spline socket that engages every HG-pattern cassette lockring in current production, sized to a 24 mm wrench flat and a 1/2" ratchet socket on the back end. It's the bench version of the cassette-removal tool, the one that lives in the same drawer as your ratchet and breaker bar.

The HG (Hyperglide) lockring pattern is the dominant freehub-mount standard. Shimano and SRAM share it across 7- through 12-speed road and MTB cassettes, including SRAM XD and XDR cassettes for 11- and 12-speed (the XD body uses an HG-pattern lockring even though the cassette interface is different). The 1670.5/4 fits any of them. The Campagnolo splined pattern is different and needs the 1670.4/4 instead.

How to use it

Seat the splined end into the lockring, register the 24 mm wrench flat or the 1/2" drive against your tool of choice, hold the cassette still with a chain whip or cassette wrench on one of the larger cogs, and turn the lockring counter-clockwise. Cassette lockrings are torqued to 40 Nm new from Shimano, 35–45 Nm from SRAM; expect a firm break-free on the first turn even if the wheel has only been ridden a season.

If the lockring tool wants to skip out of the splines under load, that's the case for the cassette lockring tool with guide pin 1670.7/4 or the integrated handle version 1670.8/2BI-US instead. The 1670.5/4 is the right pick when you're already set up with a ratchet and you want the smallest, simplest tool on the bench that gets the job done.

Compatibility

• Shimano HG cassettes, 7- through 12-speed
• SRAM HG cassettes (XD and XDR included; the lockring pattern matches)
• Microshift and Sunrace cassettes using the Shimano HG lockring pattern
• Not for Campagnolo (use 1670.4/4) or freewheels (use the 1670 freewheel-remover series)

Specs

• 12-spline Shimano/SRAM HG lockring pattern
• 24 mm hex wrench flat for an adjustable wrench or torque wrench
• 1/2" square drive socket on the opposite face for a 1/2" ratchet or breaker bar
• Trivalent chrome plated to ISO 1456:2009
• Article number: 1670.5/4

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 1670.5/4 is the unadorned version of a tool the same metalwork makes in two other formats; guide-pin (1670.7/4) and integrated-handle (1670.8/2BI-US). All three start from the same splined socket; the choice is about how much help you need on the way to the lockring.

Pro tip from our mechanics

The 1670.5/4 is the right tool for a clean cassette swap, but the 24 mm wrench flat is the trap. A 24 mm wrench is wide enough that you can run out of swing room behind the dropout on some thru-axle frames before the lockring breaks free. A 1/2" ratchet stack with a short extension gives you the swing arc back without losing engagement. The cassette-replacement workflow has more on which Unior lockring variant fits which hub: When and how to replace your cassette →