I have got a cone shaped hub on my Schwinn Landmark. It is not the origal rear wheel that came with the bicycle. I took a chance and ordered the small size clamshell adapter from livefastmotors for multi-speed bicycle. My set up has over 5 gallon of fuel through the engine on bicycle and have not had any trouble with the set-up. I am a risk taker and most of the time it pays off for me.