Interrupters are akin to cross style levers, they go on the bars.
Like the kind the yuts mount on their fixies? Thougth about it but the bars are narrow and he is objecting to me making any changes to the bike...( retrogrouch and he's only 13!!! go figure!) He insists I leave it as is and even googled up this picture just to prove to me they're fine.
Now he wants a steel water bottle just like in the picture! Kids got good taste anyway?!