Hello: Am completely new to motorized bike. Have ordered my first kit...expecting it to arrive Monday. It is a center mount, with a rear wheel, chain drive to a separate sprocket. I am thinking of converting my old Trek Mountain bike. My very basic knowledge of engineering forces me to ask the question. Except when pedaling, what effect does the multi gears have when using the engine? The reason I ask, is that I might want to opt for a more comfortable Cruiser bike instead. Know this is a dumb question, but I am advanced in age and it has been a really long time since I was in school. Appreciate any advice.