[Spock_]

Playing Standard American but not 2/1 Game Force. As Responder when I bid a suit at 2 Level, that is not a jump shift and when the opponents have passed in between, does bidding the suit show 4 or 5 of that suit? I know bidding 2 hearts always shows 5 due to the convention of bidding the lowest four card suit.

Examples are

1♦ Pass 2♣

1♥ Pass 2♦

[Gilithin]

Spock_, on 2021-July-21, 05:34, said:

Playing Standard American but not 2/1 Game Force. As Responder when I bid a suit at 2 Level, that is not a jump shift and when the opponents have passed in between, does bidding the suit show 4 or 5 of that suit? I know bidding 2 hearts always shows 5 due to the convention of bidding the lowest four card suit.

Examples are

1♦ Pass 2♣

1♥ Pass 2♦

For the suit below yours, the key to understanding is always the (4333) hand. 1♠ - 2♥ shows 5 because with 3433 the correct response is 2♣. It has nothing to do with bidding the lowest 4 card suit.

After a 1♦ opening, we would respond 2♣ with a 3334 hand. If the 1♦ opening shows 4+ then this is typically the only shape where the 2♣ response is not 5+. If 1♦ is 3+ then you might also make the call with (32)44.

After a 4+ 1♥ opening, we would always respond 2♦ with a 3343 hand of suitable strength. If 1♥ promises 5+ then we could in theory always raise with 3♥ and therefore make 2♦ 5+. But most pairs prefer to differentiate more clearly between 3 and 4 hearts rather than 4 and 5 diamonds and therefore will respond 2♦ on many of those 3343 hands.

[Winstonm]

The system you play is designed to show strength before length so your first duty is to describe your strength to your partner which means sometimes bidding 4-card or even occasionally a 3-card minor suit.

As opener, you should not raise responder’s minor suit without 4-card support.

[steve2005]

2♣ could even be a 3-card suit in some cases

[mycroft]

Do remember that a lot of the 4333 hands that can't just raise bid the appropriate number of NT.

Playing Standard American, 1♥ is 5. So the choice with 4333 is raise or NT (almost always raise). 3=2=4=4 might bid 2♦ (I'd probably bid 2♣ always, but bridge always always means "except when it's clearly wrong"), but I'd expect 5 for 1♥-2♦.

1♦-2♣ is an awful sequence in any system, but 5cM in particular. There are page-long conventions specifically for this auction (which I don't play, but you get the point).