Three-Way Wrench 2, 2.5, 3mm Straight Tip Hex

Derailleur limit screws. Bar-end plug screws. The small grub screws on a shifter clamp that hold the index ring in place. The size cluster that lives at the small end of a typical bike's fastener spectrum, on a single Y-handle that puts each size on its own dedicated arm.

The 2, 2.5, and 3 mm hex sizes are the ones that round most easily when you reach for the wrong driver: a 2.5 mm in a 3 mm recess feels almost-right, then turns the bolt into a slot under load. A dedicated three-arm Y-handle keeps each size separated and immediately findable, so the right driver is always one quarter-turn of the tool away.

The shanks are chrome-vanadium steel, hardened and tempered. Tips are black-oxide treated for corrosion resistance and a tight fit into the hex recess; on these small sizes especially, a clean tip-to-recess fit is what stops the bolt from rounding under shop torque. The glass-fibre-reinforced polypropylene handle is balanced so the unused arms don't fight you while you spin the third.

What it's for

2 mm is the size for derailleur limit screws on most current Shimano and SRAM mechanical groupsets, plus the grub screws on some shifter index assemblies. 2.5 mm covers disc-brake caliper banjo bolts on some hydraulic systems and the smaller bolts on shifter clamps and saddle-rail clamps. 3 mm shows up on older shifter and brake-lever pinch bolts, plus the small fasteners that hold bar-end plugs in some grip designs. Together, these three sizes cover the fasteners on a bike where light, precise driver fit matters more than torque.

Specs

• 2, 2.5, 3 mm straight-tip hex sizes on a three-arm Y-handle
• Chrome-vanadium steel shanks, hardened and tempered
• Black-oxide tip treatment for corrosion resistance and recess fit
• Trivalent chrome plating to ISO 1456:2009 on the non-tip shank surfaces
• Glass-fibre-reinforced polypropylene handle
• Hex keys manufactured to the ISO 2936 dimensional standard for metric hex keys
• Manufactured in Slovenia

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 small-size cluster gets the same chrome-vanadium shank and black-oxide tip as the larger Y-handles in the line; the construction doesn't drop off for the small sizes the way it does on some kit-bundled hex sets, where the smaller tools are stamped from softer steel to keep cost down.

Pro tip from our mechanics

The small sizes are where worn drivers do the most damage. A 2 mm tip that's been used for years on misaligned engagements develops worn flats, then rounds a fresh grub screw on first contact. If you notice the fit feels loose, replace the driver; these sizes are cheap enough that there's no reason to fight a worn one.

For the rest of the metric hex span (4, 5, 6, 8, 10 mm) and how to decide between Y-handle, T-handle, and L-key formats for the bolts a typical bike presents: Hex and Torx wrenches: how to pick the right tool for the job →.