Likewise for the wheelbase, downtube size is the end result on the designer’s selections similar as to the size of The top tube, seat tube, and best tube. Earlier racing bicycles mounted their shift levers on the down tube. On Newer designs, These are mounted on handlebars with brake levers. https://bikeengine2stroke40504.pages10.com/fascination-about-go-karts-plus-70360683