Joined: Jul 2015
Posts: 7,498
Likes: 3,301
From: NW Oregon
Bikes: 1982 Trek 930R Custom, '91 Diamondback Ascent w/ XT, XTR updates, Fuji Team Pro CF road flyer, Specialized Sirrus Gravel Convert, '09 Comencal Meta 5.5 XC, '02 Marin MBX500, '84 Gitane Criterium bike
21.7mm stem.. they exist... and they are mostly old. i hhave two bins of gooseneck stems here...One of the 21.7mm is an old Sakae Ringyo, SR brand, and all aluminum.. the others are steel or BMX steel with an aluminum BMX style clamp...
i have some that are 21.7mm.. and more that are 21mm, or slightly under... one of the 21.7mm stems is an ancient Antique Cast Iron beauty that weighs around two pounds.
i think older Peugeots used an undersize stem at times... those were Pivo brand, IIRC, but might be a 22mm instead of a 22.2mm, which is the most common size for a 1" threaded steerer fork.
the 21.7mm size would be found in old style, lower grade steel forks that needed the extra-thick tube for safety.. newer alloys and tube mfg. tech. were much stronger. and could be made with thinner walls.
BMX people can bend ANYTHING, so they went with the thicker wall tubes... I've worked on cheap steel BMX bikes that weigh more than my old drum brake Tandem does... the BMX bikes still get bent up.
Schwinn used a 21.1mm Stem... talkin' about Old, Chicago Schwinns, not the new taiwan ones...
Last edited by maddog34; 11-30-24 at 05:37 PM.