Amazon.com : LERWAY Bike Stem Riser Extender MTB Handlebar Stem Adapter with Hex Key for 1-1/8" 28.6mm Fork Aluminum Black : Bike Stems And Parts : Sports & Outdoors
Install New 160mm Mountain Bike Fork With Internal Stem Extender - YouTube
Bicycle Head Up Adapter Adjustable Height Extender Fork Stem Steerer Tube | eBay
How to extend a steerer tube - Framebuilding 101 with Paul Brodie - YouTube