Quill stems were most popular in the 1970's and 1980's for BMX bicycles. Early BMX bicycles had issues with weak forks so the tubing was thickened. The industry kept the 1" outer diameter, necessitating a smaller diameter quill (21.1mm). Always measure to determine if your bike uses a 21.1mm or 22.2mm quill. Quill stems were phased out of BMX in the 1990's for all but the cheapest department store bicycles.