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 sponsors professional road and mountain-bike race 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 →