Years ago I bought a set of Sunrace SLM10 thumbshifters along withe some Falcon ones. I've never used them, but you can still buy them retail. They both have ratchets, albeit plastic, but they work just fine. Looking at buyer comments it's about common issues with any thumbshifter, like the shifter needing retightened, or the cables fraying, or "my dog ate my shifters and now they're junk... what crappy shifters, one star !" People are nuts.