(but rim brakes and 20″ wheels, probably very unlikely in the real world).Are you 12 and living in France? Just why? :)
Anyway, I use them on road bike, Ridenow, as fitted tubes, I carry 2 x butyl spares in spares bottle. on the bike conti 5000s, and they are faster rolling than standard tubes, mate has exactly same bike and contis, but butyl tubes. He has to pedal to keep up on a descent when I freewheel.
I’m still not confident enough to use them as spares as I could be 50 miles or more from home/car and apparently they are hard to patch. (Although I have two on the table ready to use, just need to go for it!)
Problem I found was pumping up a presta valve tube, ramming on trackpump hose, pushing valve into wheel, and causing failure at valve/tube join. Cured by using a schrader /presta tip attachment. (also useful for garage air lines)