Marc
I sympathise with you and your fear of bears.

Why are you going to Yosemite? Partly to see the bears? Park bears are not a threat. In all the time I've spent in Yosemite, and that is considerable, I've never been closer than 100 to a bear and it was going the other way and totally ignoring me.

Assuming you will be attacked by a bear is just not reasonable. You are more apt to be struck by lightening (literally) or to have a rock fall on you. Its not worth the weight of belly button fuzz to carry bear spray. You can't even season your food with it.

Before I leave I want to say tht being dependent on technology and percieved safety through hardware is a false sense of security. Even if you are armed with a cannon, you still have to be skilled with its use, and have it available. The only real potentially dangerous animal enounters that I have had lasted a couple of seconds and there was no time to even draw a gun if I had one. My body language was all it took.

And bears are not in the slightest bit interested in YOU. This is kind of a narcicistic attitude that you are so special that you will be the 7585th person and you will be the one to be eaten. Worry about something more reasonable, like giardia.
Jim