Feeler Gauges

A feeler gauge set lives in the toolbox until the day you need it, and then it's the only tool that does the job. Setting a SRAM front derailleur to manufacturer-spec gap requires a feeler gauge. Verifying that a brake-caliper-to-rotor gap matches Shimano's spec requires a feeler gauge. Measuring the gap in a stuck bearing race before you commit to the puller requires a feeler gauge.

The set is 13 gauges from 0.05 mm to 1 mm. That range covers every measurement spec you'll see in a modern bike service manual. SRAM's front-derailleur outer-cage gap is 1.0 mm. Shimano's pad-to-rotor minimum is around 0.3 mm. Bearing-race wear shows up as gaps in the 0.05–0.15 mm range. Each gauge is a steel blade with the size etched into the handle, hinged at one end so the whole set fans out from a single hub.

The gauges are flat-ground steel, not stamped. Stamped gauges deflect under finger pressure and read shorter than nominal; ground gauges hold the etched dimension. The pressure on the gauge matters: a gauge that pushes in with light resistance is the right size. A gauge that snags is too thick. A gauge that drops through is too thin.

When you'll reach for them

• Setting SRAM front-derailleur outer-cage gap (per the manual's spec for the specific derailleur)
• Checking brake-pad-to-rotor clearance against the brake manufacturer's published minimum
• Measuring bearing race wear before deciding whether to re-grease or replace
• Setting valve clearances on internal-combustion engines (the gauges aren't bike-specific; they cover any feeler-gauge work)
• Quickly checking whether a stuck rotor bolt has any clearance to a backing plate

Specs

• 13 gauges, 0.05 mm to 1 mm
• Flat-ground steel blades
• Article number: 701

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. Feeler gauges are a general workshop tool, not bike-specific, but the manufacturing quality matters: gauges that read true the first time save the trial-and-error of trying three blades to find the right one. The 701 set is part of the same hand-tools line that the cycling catalog draws from.

Pro tip from our mechanics

A SRAM front derailleur with the wrong outer-cage gap will ghost-shift under load even when the indexing is perfect. The clearance spec is in the manual; the feeler gauge is what makes the spec usable. Our workshop hand tools guide covers the measurement tools and other workshop fundamentals that quietly carry half the daily work: Workshop hand tools every bike shop needs →