Pin Punch

A pin punch is the small specialty tool that turns a tricky pin-removal job into a controlled five-second operation. Drive a chain rivet through a stuck plate. Re-seat a hanger stud that's working loose. Reset a stripped pedal-thread insert. The job is always the same: align a sharp-tipped punch against a pin, strike the back end with a hammer, and the pin moves where you want it.

The 641/6 is the 3 mm pin punch; the size that matches chain rivet pins on 5- through 13-speed derailleur chains. Chrome-vanadium steel, fully hardened and tempered, with an induction-hardened tip for life under cumulative strikes.

What it does well

The 3 mm tip diameter is the standard size for bike-chain rivet replacement work. Shimano, SRAM, and Campagnolo all use rivet pins in this nominal diameter, which means the same punch covers chain-pin work across every drivetrain you'll encounter.

The induction-hardened tip is the wear-resistance choice for the working surface. The rest of the punch body is hardened and tempered uniformly (so it doesn't fracture under strike load); the tip is induction-hardened separately for additional surface hardness where the contact happens. The result is a punch tip that stays sharp through hundreds of strikes; soft tips deform after a few uses and slip off the pin under hammer impact.

The 150 mm overall length gives you a comfortable grip without putting your hand near the strike zone. Long enough to hold steady, short enough to control.

Where it earns its space in the bike shop

• Chain rivet replacement on chains that don't use master links. Some traditional Shimano chains still use rivet-pin connectors.
• Hanger stud installation. Driving a hanger stud through a frame dropout when the threads have stripped and a press isn't available.
• Pedal-thread insert work. Re-seating an insert after thread repair.
• Chain-tool pin replacement. When a chain-tool driving pin breaks, the punch helps remove the broken pin from the chain tool.
• General precision-strike work. When you need to drive something through a specific aligned path.

How to use it correctly

• Align the punch tip square against the workpiece. Off-axis strikes round both the punch tip and the workpiece surface.
• Strike with a steel-faced hammer (the locksmith hammer 812) for maximum energy transfer. A dead-blow hammer can also work but transfers less energy.
• Keep your strike force matched to the workpiece. Soft pins (chain rivets) need controlled taps; harder pins (hanger studs) need more energy.
• Re-seat the punch between strikes if you feel it shift off-axis.

Specs

• Pin diameter: 3 mm at the tip
• Overall length: 150 mm
• Material: chrome-vanadium steel
• Manufacturing standard: DIN 6450
• Hardening: fully hardened and tempered through; induction-hardened tip
• Made in Europe

Made in Slovenia, since 1919

Unior has been forging hand tools in Zreče since 1919, and is the official technical partner of multiple World Tour and downhill teams. The DIN 6450 standard specifies pin-punch dimensions and hardness; the spec we manufacture to, and the spec that determines whether the punch fits the pin correctly. An off-spec pin punch will either slip off the pin on the strike or rest on the surrounding workpiece instead of contacting the pin cleanly. The dimensional tolerance is what keeps the strike precise.

Pro tip from our mechanics

Keep a 3 mm and a 4 mm pin punch in the drawer. The 3 mm covers chain work; the 4 mm covers most other bike-shop pin sizes. For the framework on which striking tool fits which job: Hammers and striking tools in the bike shop →.