hey guys, first post and I’m a newbie to bike building. I want to build an adult sized gas powered replica (as close as possible) to a radio flyer kids tricycle. I have the gas BBR frame with the build in tank. Two 20 inch rear and putting on a 26 inch front wheel. I need help with what to buy that you don’t see in the photo. Especially when it comes to the gears. The back is a trike conversion 7 speed I bought off eBay.