Why is my cake so crumbly

[islandbaby]

Hi all. I've made a delicious banana and chocolate tea bread a few times now following an old recipe in a book. It really is delicious, but it always crumbles when I try to cut pieces, and I have no idea why. Any cake experts can tell me what it is that keeps a cake together? (more egg/milk/flour etc??)

Here' the recipe
2 cups unsifted all-purpose flour
1 cup sugar
1 tsp baking powder
1 tsp salt
½ tsp baking soda
1 cup mashed bananas (3 small)
½ cup melted butter
2 eggs (I've been using pretty small eggs from my garden chickens that have a lot of yolk and not much white)
1 cup chocolate chips
½ cup chopped walnuts

(sorry for the cup measurements, that's how it is in the book and I happen to have cup measurers here)

Thanks!

How long are you cooking it for?

2 small eggs doesn't sound like much for around 250g flour.
I think I'd try adding another egg next time and see if it improves the texture.

it's taking around 55 mins to cook to a nice moist yet cooked texture. Any more and it starts to get too dark. An extra egg sounds like a start. Thanks

Possibly because the eggs you're using are small, if the recipe says 2 eggs it's probably correct but you should ideally use large eggs unless recipe says otherwise. So another small egg should help.
Lots of things like too much flour, or too little fat can make a cake crumbly but I don't have a clue what the cups mean!
Also, don't over mix.

The eggs are probably the cause of your problem. I am not suggesting that they are anything other than the best quality imaginable, but you need to check the size of them. The recipe, if all measured in Cups, is probably American (?). There is a very slight difference in size between American and European Cups, but it is very small (1.5%). The difference is in the size of Egg. A UK "Medium" egg is known as a "Large" egg in the US, and would generally weigh around 60gms (about 2 ozs). It is certainly worth looking at that.