My sourdough starter is bubbling but not rising, suggestions? I've been trying to grow my own sourdough starter; I went with a 'pure' method, with 50g each of hard-wheat flour from a local mill and water.  I've fed it once and it seems to be bubbling nicely after a couple of days, and the taste is nice and tangy, but I'm not noticing the increase in volume that I would expect.  The area I'm in (the Pacific NW) is still fairly cold (the interior temp in my house is probably mid- to upper-60s) so I suspect that could be a factor, but at what point (I'm about 4 days in now, including a second divide-and-feed pass a day or two ago) should I start to expect any real vigorous expansion out of the starter?
If the starter is "bubbling nicely" then you may be already there.

Bread rises because the CO2 produced by the yeast is trapped by the protein in the dough. If you see bubbles then your starter is already producing the necessary CO2.

A starter has so much water in it that the protein doesn't trap the gas- thus you see bubbles rise to the surface. If you expect your starter to trap the gas and expand then it would have to have more protein. This isn't required for a starter to work.

You should be able to use the starter in a bread dough and that bubbling will turn into rising.