Bread – Does 100% rye sourdough bread always have a sticky crumb? How to make it stick to the knife less

Generally when you have issues regarding oven spring at home, the problem is heat and steam in your oven rather than yeast activity. In commercial bakeries, sourdoughs are frequently fermented for overnight or longer, so that shouldn't be a problem. A lot of the expansion you see in the oven is from the moisture in your dough converting to steam before the crust has set. In a bakery, we can achieve this by using steam injected ovens which allow the crust to remain elastic longer. Bakeries also use hearth and convection ovens which transfer heat into the loaf more efficiently causing it to create steam faster.

To recreate this at home, you can try moistening the crust of your bread before baking it or trying to create steam in your oven. You can encourage steam by starting your oven at a higher temperature and turning it down after a few minutes, or by baking on a pizza stone to simulate a hearth. It's important to get the steam down first though, as the heat transfer without steam will cause a lot of crust cracking and weird rising.

It's also important to note that if your dough has a high proportion of rye flour, rye traps bubbles via gums called pentosans rather than via a gluten network like wheat dough. It generally won't rise in the same way that wheat doughs will.

Your recipe is to blame.

Your dough is stiff and tears because it isn't wet enough. While different types of flour do absorb different quantities of water, I think most of the issues you're experiencing are due to the ambiguousness of the recipe and instructions you're using. Most sourdough recipes yield dough around 80% hydration (the weight of water/the weight of flour). The recipe you've cited relies on the starter providing all the hydration for the dough. Doing the math, following the feeding instructions, you would have a starter that is 55% hydration. Adding all the flour called for in the dough recipe, you would end up with a dough that is about 45% hydration... stiffer than bagels (50-55%).

While it is possible to make dough that doesn't have any added water, it is not common, especially with such a stiff starter. Also, the volume of flour would be much smaller than the volume of starter.

Try using a tried and true recipe that doesn't rely on the starter to provide all of the hydration.

Don't worry so much about gluten production and how sugar or fat will affect it. Small amounts of these enrichments, like those in the recipe you linked to, will soften the interior of the bread and help the crust brown nicely. Just look at brioche if you want an example of how far you can push enrichment and still get a well structured bread.