Urbana has created what it calls the strongest rack available, bar none. From the press release:
The RNR is designed with a reinforced lateral plate that allows the rack to hold up to 150 lbs in dynamic weight and serves as an anti-wobble mounting point that keeps the bike stable when there is heavy load on it. So, not only is it capable of withstanding enormous vertical forces, it can take the real life horizontal forces that challenge a commuter in an actual commute.
It’s designed to accommodate just about any typical pannier, grocery or other common bag and mounts at the standard attachment points near the dropouts and top of the seatstays.