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 anodised; on these small sizes especially, a clean tip-to-recess fit is what stops the bolt from rounding under shop torque. The plastic-injected 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 the limit screws on many current derailleurs, 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 some shifter 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, 122 mm across the arms and 36 g
• Chrome-vanadium steel shanks, hardened and tempered
• Black anodised tips, with each arm's maximum torque printed on the handle: 1.9 N·m at 2 mm, 3.8 N·m at 2.5 mm, 6.6 N·m at 3 mm
• Trivalent chrome plating to ISO 1456:2009 on the non-tip shank surfaces
• Plastic-injected polypropylene handle
• Hex keys manufactured to the ISO 2936 dimensional standard for metric hex keys
• Article 1781/2HX-US, item 624908, covered by Unior's lifetime warranty

Built in Zreče, Slovenia

Unior has been forging hand tools in Zreče since 1919, and sponsors professional road and mountain-bike race teams. The small-size cluster gets the same chrome-vanadium shank and black anodised 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 →.

FAQ

Which bike fasteners do the 2, 2.5 and 3 mm arms cover? The small ones. In our workshop the 2 mm arm turns the limit and B-tension screws on many current derailleurs and the grub screws on some shifter index rings, the 2.5 mm arm the small clamp bolts on some shifters, and the 3 mm arm the pinch bolts on older shifters and brake levers plus bar-end plug screws. Sizes vary by maker, so check the component manual before you lean on it.

Why straight tips rather than ball ends at these sizes? A straight tip seats square in the recess and drives on the full hex flat. At 2 to 3 mm the recess is tiny, and the smaller contact patch of a ball end rounds it quickly under load, so the small sizes are straight-tip. The ball-end Y-wrench we stock, Unior 1781/2HXS-US (item 624910), covers 4, 5 and 6 mm.

What do the torque figures printed on the handle mean? They are Unior's maximum for each arm, not a tightening spec for your bolt: 1.9 N·m beside the 2 mm arm, 3.8 N·m beside the 2.5 mm arm and 6.6 N·m beside the 3 mm arm. Small fasteners usually call for less than that, so tighten to the figure the component maker publishes and reach for a torque wrench when one is given.

What are the dimensions, and is it the same handle as the 4, 5, 6 mm version? Across the arms it measures 122 mm, it stands 106 mm tall with a 16 mm handle section, and it weighs 36 g. The 4, 5, 6 mm straight-tip wrench (item 624909) shares the same 122 by 106 mm handle at 65 g, so the pair covers 2 to 6 mm with matching grips. Both are trivalent chrome plated and carry Unior's lifetime warranty.