+1 this. That's what the Wisconsin Department of Transportation tells cyclists to do in roundabouts:

Driving bicycles in a roundabout

- If you are riding on the shoulder or bike lane, merge into the traffic lane before the shoulder ends.
- Signal your intent to move into traffic.
- Once inside the roundabout, don't hug the curb.
- Ride close to the middle of the lane to prevent cars from passing and cutting you off.
- Watch for cars waiting to enter the roundabout, as they may not see you.
- If you do not want to ride your bike in the roundabout, use the sidewalk and proceed as a pedestrian.

http://wisconsindot.gov/Pages/safety...uts/works.aspx