I recall using one of these tools by pressing the wheel, set up with freewheel tool and secured with the skewer, with the horns facing down on the stem or a set of steel handlebars- like you were holding down a car's steering wheel and using the leverage of the rim and spokes to turn the freewheel and tool against the bars. It worked quite well! Unfortunately, it could mark up the alloy of the stem or bars if not padded with a rag or something. Clearly, this wouldn't be ideal with today's Carbon bars or stems, but for a tourer on an alloy fitted bike, a re-engineered version might not be a bad idea.......