Loading... Please wait...Brass presta valve adapters easily convert your bicycle tubes from presta to schrader valve. Quick Tip After you finish inflating your tire and you've screwed that little thingy down to seal the valve, screw the presta valve adapter right back on the valve and put a regular valve cap on it. The high tech boys won't do this because it adds to much rolling weight and that's fine. They keep buying adapters.