Last week I had an inquiry about Rosenkranz. That would be George Rosenkranz, a world renowned chemist, the founder of a major drug company, a pioneer and leader in the development of steroids and one of Mexico’s leading citizens. He also is a bridge expert, winning 14 North American Championships, writing 11 books on bridge and a major inventor of bridge gadgets. Perhaps he is best known in the bridge world for the popular bridge convention that still bears his name, the Rosenkranz Double and Redouble. Although the conventional bid does not receive that much attention in Florida, in other areas of the country it is almost as routine as Stayman.
In general Rosenkranz Doubles and Redoubles are used in response to an overcall by partner to describe your supporting length and top honor holding in the overcalled suit. Let’s first work on Rosencrantz Doubles.
If the bidding has gone 1d/1h/1s, a Rosenkranz Double of the 1 spade bid is purely informational and would promise partner that you have exactly 3 card support for hearts and one or more of the top 3 honors in the suit. By way of contrast, if you bid 2 hearts over 1 spade instead of doubling, it would also indicate exactly 3 cards in the heart suit, but would deny any of the top three honors. If you made a Rosenkranz Double your hand might look like (a) xx, Kxx, Axxx, Jxxx. If you bid 2 hearts you might hold (b) Kx, JTx, Axxx, Jxxx. So already we have passed some useful information to partner.
The Rosenkranz Redouble is closely related, except in this case you right hand opponent has made a negative double rather than bidding 1 spade. So the bidding has gone 1d/1h/x/. Now, if you redouble you are showing three card support to one of the top three honors and if you bid 2 hearts you still show 3 card support but deny a top honor. So with hand (a) above you redouble and with hand (b) you bid 2 hearts.
We have covered 3 card support, what do you do with 4 or 5 card support? Exit George Rosenkranz and enter Larry Cohen. We follow the law of total tricks and bid to the appropriate level. You are now out of the realm of Rosenkranz and you are just upping the ante hoping to preempt opponents or on a good day actually buy the contract. Rosenkranz Doubles and Redoubles are made on limited strength hands that are sufficient to make a single advance of the overcall. The hand should not have more 10 hcps. If you actually have 3+ card support and limit raise or greater values, then you must cue bid opener’s suit to pass this message to your partner. This is just old SAYC.
So now we can see that we have really sliced and diced advancer’s hand and completely described to overcaller the supporting strength, length and top honor holding in the overcalled suit. This information may be useful to overcaller in competitive bidding, but let’s face it, when they open the bidding, most likely we are going to be defender’s and we want to get off to a good start without giving away a trick on the opening lead. Visualize that overcaller might hold AQxxx in the overcalled suit. The best defense may to be to grab our heart tricks before they go away. But is it safe to lead? If partner had made a simple raise he does not hold the King so you would not want to lead the suit, but rather wait for partner to lead it. If advancer has made a Rosenkranz Double or Redouble, advancer is marked with the King and you can either safely lead one of your honors or underlead the Ace/Queen if you want partner to lead back through declarer. Note that we also have an exact count on the heart suit.
I should point out that some play Rosenkranz as requiring one of the top 2 honors. That is only a matter of style, but it is good to talk to partner about it. There is more assurance of not making a disastrous lead playing the top 2 only, but you don’t get to use the convention as much. Experience will tell you, and as in most things in bridge, it boils down to trade offs. The use of Rosenkranz needs to be marked on your convention card and the use of the convention is alertable.
My recommendation is to start using Rosenkranz Doubles and Redoubles and fine tune your personal preference from there. There is very little downside, the convention has a relatively high level of occurrence and is easy to recognize. Partner will be happy to know that you have 3 card support, and even happier if you have one of the top three honors.
To my critics who allege that I never provide any useful stuff, this blog post is my best defense.