Check the laws. I have two roundabouts on one of my favorite rides. The sign posted says bike lane ends. That's all. So as I approach the roundabout, I check behind me for cars. When it appears safe enough, I take to the middle of the lane and proceed through the roundabout. Once clear I pull back into the bike lane when it picks back up.

I take to the middle of the lane because I have had people actually try and get around me in the roundabout. Aholes for certain, not remotely thinking of the danger they are creating. I'll bet there is no law stating you cannot maintain your ground on the road. Be careful either way.