I bought my first road bike with presta valves, and i had that little adapter. It was a less-than-perfect solution, and I could never be sure the tire pressure was where i wanted it, because air would leak around the adapter. I went to my lbs, bought a new 20 dollar floor pump with a pressure gauge, and it locks securely onto the presta valve, without bending it or leaking in any way. Definitely a good 20 dollars spent.