This is my version of a stem-mounted switch. It essentially replaces the top cap. I made V1 for Mark VandeKamp years ago and then decided to add one to my bike for my first PBP in 2011. I ended up really enjoying it and have refined the design several times.

It’s available for both 1” and 1 1/8” thread-less steer tubes. It comes with push-on connectors for the wires in the steer tube, which was the final tweak to make it easy when rinko-ing my bike. The switch simply pulls out of the top cap, a friction fit using o-rings, and then you adjust or disassemble the headset as usual.