Lol
Guess why he doesn't try pignonfixe.com !
He's smart enough to know that buying a bike on leboncoin and trying to sell it 2 days after for 5 to 10 time the price in a well informed community is a bit tricky.
Smart enough is not applying here for some unknown reasons...
What about this one ?
https://m.ebay.fr/itm/Potence-route-CONTROL-TECH-Road-Stem-1-1-4-NOS-Neuve/123745909178?_mwBanner=1&_rdt=1&pageci=26edb663-a693-47a5-8120-c247ad1ad74b