I want to change out the straight bar to a riser. Anyone have any idea what size bar I should get. Id like to keep the stem thats on the bike but will replace it if needed. The bike is pretty light and Id like to keep it that way but im also cheap so overall whats the best material to go with?

Finally does a riser bar have any advantages or disavantages? I know what Im hoping to achieve but not sure if it will give me what Im looking for. Basically the bike feels just a little to big so im hoping the bar picking me up a little does the trick.