Blackwood and Gerber are two common ace asking conventions in bridge. What's the difference? Which one is best?
The Blackwood convention uses 4NT to ask partner for their number of aces. The responses are:
Gerber uses 4♣ to ask partner for aces. The responses are:
At first glance Gerber looks pretty good because it keeps the bidding lower. However, expert players rarely use this convention. Why not?
The biggest downside of Gerber is that it takes away the valuable 4♣ bid that could be used in many more helpful ways. Cue bidding or splinters, for example, both of which are great slam bidding tools. Heck, 4♣ as a natural bid showing clubs is often exactly what you'd like to be able to do on a hand.
Blackwood starts at a higher level, meaning that the response will take you higher, but rushing off to ask for aces often isn't the best way to explore slam.