Oh, and one tip to get more food inside the bag: the bag comes with a scent-resistant liner, so stuff that full of any food that might possibly have a scent. Packaged foods that will have little scent (e.g., freeze-dried, packaged meals, like Mountain House entrees) can be stored inside the Ursack, but outside the scent-resistant liner.
Finally, if you are new to travelling in bear country, make SURE that you holler a lot any time you can't see more than 50-100 m in front of you, like on a trail that takes a turn through the bush. Most bike-bear encounters occur when a cyclists startles a bear (unfortunately, one mountain biker in Montana was killed last year near the GDMBR by a grizzly that he collided with because he didn't see it in time). I actually carry a refillable air horn for this purpose, just to keep from going hoarse. And literally, I have hollered ahead and had a bear jump out of the bushes along the side of the trail (proved to me the effort was worthwhile!!).
Thanks for the advice. I own a Timber bell to make a constant noise, but have the impression that this mostly annoys me and you can hardly hear it 30m in front of me.
About the scent resistance; I've read toothpaste should also go into the bag, are bears also attracted to human scents? Anything we should do to make us less attractive while sleeping?