Shimano Hollowtech II / M20 x 1.0 Thread Adapter



This adapter was developed primarily for Shimano Hollowtech II road cranksets which are not compatible with the Expanding Crank Adapter.

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


  • M20 x 1.0 external threads 9 mm deep


  • Machined 303 stainless steel


On Hollowtech II applications the molded crank arm cap must be removed to expose the internal threads (photos below).

The drive features are unique and require a purpose designed tool. Two options are the Shimano TL-FC16 and Park Tools BBT-10. The Park tool is more expensive but can provide greater removal torque that will likely be required if the cap has never been removed.

The Shimano part description for this cap is a "crank arm fixing bolt", as on crankset installation it draws the crank arm inward to create the desired pre-load.  The Adapter should be installed manually if possible. The wrench flats are only provided to overcome grit or minor nicks in the threads if present. No additional torque should be applied once the adapter is seated.


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.