these
are intended for the downtube -- I'd expect the "dent" to be centered -- but might work on the handlebars (where the proper "dent" is off-center, so that the bolt/nut are under the bar, out of the way of your knuckles).
They might have some of the clips that would work for the handlebars, too.
-- Joel Niemi / Snohomish, Washington, USA