I live in Austin, and pretty much every bike has a u lock, for good reason. However, u locks aren't always convenient, and sometimes, I like to go on a training/fun ride and leave my bike somewhere while I go explore, read, eat or whatnot. I would like to get one of those combination chain locks that I can sling around my waist while I ride, and conveniently lock my bike up when I want to leave it outside a store for a while or something.

Anyone have experience with these? How secure are they? recommendations?

They are less secure than U-locks, as they will be easier to cut through. But my only bike lock is a simple (Master-brand) coiled cable lock, with a key though, not a combination. My suburban environment is pretty safe, so I am comfortable with that level of protection, and it has been working for a couple years so far.

Apparently it is urban biker chic to have a chain with gigantic (2-3" ea?) heavy links, and a padlock or U-lock to secure the ends, and wear it as a belt, if that strikes your fancy.

yea, I've seen those. They're over $100, and weigh around 5 lbs. No thanks.