First, I want to say hello to everyone on this forum. It's my first backgammon post.

My question is simple : how do you change your doubling cube strategy when you are close to the limit of the game ?

For exemple you play cash BG, 1$ per point, but the stake is limit to 2$.
So the cube can't be on 4 and winning a gammon with the cube on 1 or 2 is the same result (2$).

Should you double when your equity is just a little over 50% ?

thanks for answering, this question is bothering me for a long time

No, you should still stick pretty close to the normal guidelines for offering doubles.

One reason why you don't double automatically as soon as you get a small edge: you'll still have the opportunity to double when your edge is larger later in the match. Don't offer the cube at 55% when there's a decent chance you'll be in the range of 65%-75% to win later in the game, and you can offer a more powerful double at that point.

Compared to a normal cash game with (theoretically) unlimited bankrolls, the situation you describe is different in two ways:

1) Dead cube. After you double, your opponent can't redouble. Being able to redouble is a strong asset for the taker, so this argues for somewhat earlier doubles for the player with an advantage.

2) No gammons. After you double, you can't win a 4-point gammon; a gammon just counts as two points, like a regular win. So a position where you are, say, 62% to win but your wins are 25% gammons and 37% single games, becomes just a position where you win 62% of the time. This means you're probably not doubling for another turn or two.

The net effect works like this:

> In non-gammonish, non-volatile positions, you'll double a little sooner than normal, because your opponent has no cube ownership.

> In volatile, gammonish positions, you'll double later, because there aren't any gammons or backgammons.

> In volatile, but basically non-gammonish position, you'll double pretty much when you would otherwise. You want to double before you roll the crushing sequence that makes you an 85% favorite, not afterwards.

Hope this helps. The limit cap is an online invention to let players minimize their possible losses. Setting a limit to 16 times the original stake results in a game that plays very much like normal live cash games, as 16 cubes are very rare between reasonable players.