Expanding Crank Adapter



This adapter expands into cranksets designed with hollow shaft exposing a large opening at their centerline.

The pin extending from the adapter provides a stable reference point for VeloAngle to rotate between saddle and handlebar measurements. Because this measurement point is fixed and aligned with the crank axis, the saddle and handlebar adapter straps are not required to maintain tool orientation.


  • Adapter assembly
  • Second expanding bushing to provide full range of application


  • Compatible with Crank Shaft ID between 0.80 – 1.18 in. (20.3 – 30.0 mm) and at least 0.50 in. (12.7 mm) deep. This encompasses the vast majority of hollow shaft cranksets.
  • Wrench Flats: Pin: 10mm, Flange: 15 mm.


  • Pin, Flange and Nut: Machined 303 stainless steel
  • Expanding Bushing: Neoprene
  • Bushing Liner: Sintered bronze


The advanced cranksets for which this adapter was designed generally integrate the shaft and a crank arm to increase stiffness while reducing weight. A typical example is shown below.

Install using the largest of the rubber bushings that can be inserted into the bore. Rotate the shaft while maintaining flange contact with the crank arm, as shown below. This causes the bushing to shorten and expand against the bore ID, clamping the adapter in place.


The fixed pin provides the ideal measurement reference point. As the maximum allowed clearance between the pin and mating bushing is 0.0025” (0.063 mm), the far end of VeloAngle will remain aligned to the pin at throughout its measurement range.


As shown in the home page video, once these fixed adapters are installed the relationship between cranks, saddle and handlebars can be captured in as little as one minute.