Most monetary policy committees decide on interest rates using a simple majority voting rule. Given the inherent heterogeneity of committee members, this voting rule is suboptimal in terms of the quality of the interest rate decision, but popular for other (political) reasons. We show that a clustering of committee members into two subgroups, as is the case in hub-and-spokes systems of central banks (e.g. the Fed or the ESCB), can eliminate this inefficiency whilst retaining the simple majority voting rule. JEL-Codes D71, D78, E58