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CalipERD™ Rim Measuring Device

SKU: CALIPERD

$250.00

A caliper to measure ERD – Effective Rim Diameter – used in spoked wheel building.

Product Description

Get your spoke lengths exactly right with CalipERD! This tool measures Effective Rim Diameter – the most critical dimension when determining spoke length.

Current methods to measure rims are clumsy and imprecise. With this tool you can get results that are Accurate, Precise, Repeatable, & Fast.

This provides the perfect spoke length by determining the correct nipple seat diameter.

Use as a strict measuring tool or enjoy the adjustable window to allow one-shot exact ERD measurement!

  • Provides direct measurement of a rim
  • Adjustable calibration window
  • Measures nearly any rim!
    • up to 750mm reliably (fits 32″ and 36″ rims)
      • 125mm minimum (~ 12″)
    • 53mm throat/swing/reach distance – fits most fatbike rims
    • 100mm feeler depth – fits 80mm deep aero rims (theoretically 100mm but untested)
  • Precise to within .5mm
  • Interchangeable Feelers for different applications
    • includes Standard Nipple and Internal Nipple Feeler Sets (v1.1, April 2025)
  • Includes calibration tool

 

Use cases include:

  • Checking factory specifications
  • Obtaining Data-driven roundness of a rim
  • Verifying stated dimensions of Manufacturer
    • (are they suggesting an actual ERD? Based on which nipple?? Do they mean Nipple Seat Diameter? Using their own washers???)

 

 

CalipERD™ Instruction Manual v1.1

 

CalipERD

Additional Information

Weight 475 g
Dimensions 39 × 5 × 7 in
Knob Color

Orange, Blue, Red, Green