Half-round File with Handle

A half-round file has a flat face on one side and a half-round (curved) face on the other. That geometry lets one file do two jobs: file a flat surface like a flat file does, and follow the inside of a curve like a round file does. For a bike shop, the most common use is deburring the cut end of a steerer or seatpost where both the outside-of-the-tube and the inside-of-the-tube need work.

The bastard cut is the middle-aggressive tooth pattern; coarser than smooth, finer than rough. It removes burrs and shapes material at a rate that matches the working speed of a hand mechanic. A fine-cut file would take ten times the strokes; a rough-cut file would over-cut and leave gouges.

Where the half-round is the right call

• Deburring a cut steerer. The outside-of-tube edge gets the flat face; the inside-of-tube edge (which the headset compression cap rides against) gets the curved face. One file does both.
• Following a curved part profile. A worn-out brake-pad surface that's developed a concave wear pattern can be flat-filed to spec, but a half-round file lets you follow the curve more closely without removing more material than needed.
• Cleaning up a damaged thread shoulder. Where a thread meets an adjacent radius, a flat file struggles to follow the geometry; the half-round drops into the radius cleanly.
• Opening up a small undersized hole or recess in soft material. Less common in bike work, but occasional on accessory mounting brackets and the like.

For straight-line flat work (deglazing brake pads, deburring flat edges), the flat bastard file is faster. For small-hole work, the round file is the right tool. Most shops own all three.

Specs

• Half-round profile (flat face one side, curved face other)
• Bastard cut, second-cut teeth
• Premium hard plus carbon steel
• Wooden handle pre-fitted
• Hanging hole

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 half-round file shares construction with the flat and round files: same carbon-steel stock, same heat-treatment, same wooden-handle fit. The three profiles together cover the bicycle-workshop file work that no single profile can.

Pro tip from our mechanics

The trick to using a half-round file effectively is keeping the right face engaged with the right surface. The flat face handles flats, the curved face handles curves; switching mid-stroke causes the file to chatter and leaves an inconsistent finish. One face per stroke, lift the file on the return, and the finish stays clean. Our workshop hand tools guide covers the file line and the rest of the workshop hand-tool layer: Workshop hand tools every bike shop needs →