That all depends on the type of road gear ..If your talking leathers , you need to try them on in shop ... too tight you cant ride properly too loose in an accident you will pinch your skin and they will be useless .. if you do buy leathers on line and they are too big small ,I know of a guy who will alter them in Melbourne any brand.. He adjust my race leathers as I add weight and so on .
Also with boots if buying online 1 size bigger always an be filled with a winter sock ..