Metric Hex Screwdriver

The straight-shaft hex in a screwdriver format. Same hex tip as the T-handle and Y-handle hex tools in the line, on a long-axis screwdriver handle that reaches into the deep-recess fasteners a cross-bar handle can't enter. Available individually across the metric hex sizes the 620 line covers.

The straight-shaft format is the right call for two situations: where the bolt sits below a recess that a T-handle's cross-bar would foul against, and where a long-axis grip lets you hold the tool perpendicular to the work surface for the final torque pass. Stem cap bolts under a recessed top cover, derailleur limit screws sunk behind a guard, brake-pad retention bolts inside a caliper. These are the fasteners that need a screwdriver shape rather than a T or Y.

The chrome-vanadium shank is hardened and tempered, with a black-oxide tip for corrosion resistance and a clean fit into the hex recess. The handle is a three-material composition: a hard core for torque transmission, a softer outer for comfort under repeated use, and a hex bolster at the base for wrench-assist torque on the high end of the working range. The shank length is sized for bike-fastener reach, long enough to access recessed bolts and short enough to fit on a tool rack without sag.

Compatibility

The 620 line covers the bike-relevant metric hex span, sized per individual order:

• 2.5 mm: disc-brake caliper banjo bolts on some hydraulic systems
• 3 mm: older shifter and brake-lever pinch bolts
• 4 mm: stem face-plate bolts; brake-lever clamps; bottle-cage bolts
• 5 mm: stem steerer-clamp bolts; seatpost binders
• 6 mm: disc-brake caliper-mount bolts; some chainring bolts
• 8 mm: pedal threads from inside; some crank-fixing bolts
• 10 mm: Campagnolo crank-spindle bolts

The straight-shaft format earns its place when access geometry rules out a T-handle. For the most-reached sizes (4, 5, 6 mm), most shops keep a straight-shaft screwdriver alongside a T-handle of the same size; the two formats cover different access conditions on the same fastener.

Specs

• Single-size straight-shaft hex screwdriver (size selected at order)
• Chrome-vanadium steel shank, hardened and tempered
• Black-oxide tip treatment for corrosion resistance and recess fit
• Three-material composition handle
• Hex bolster at the handle base for wrench-assist torque
• Trivalent chrome plating to ISO 1456:2009 on the non-tip shank surfaces
• Hex tip 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 straight-shaft hex screwdriver is the same hex-tip geometry as the T-handle and Y-handle hex tools in the line, on a different handle format; the construction and dimensional tolerances are shared across formats.

Pro tip from our mechanics

A screwdriver-format hex doesn't replace a T-handle or Y-handle; it adds a third format that covers the access conditions the other two can't. The fastener layouts most likely to need this tool: derailleur limit screws on rear mechs where a guard sits behind the bolt, brake-pad retention bolts that pass through the caliper body, stem cap bolts on bikes where the steerer cover sits proud of the surrounding bezel.

For when the straight-shaft hex format beats a T-handle or Y-handle, and the access-condition decision tree for the most-reached bike hex sizes: Hex and Torx wrenches: how to pick the right tool for the job →.