I have that bag!! I love it!!! I don't have an SLR, but a fancy POS. I worry about the jarring, but it's very padded and had a velcro shelf to suspend the camera.
I wish I'd seen this before, but you got the bag anyway.
I have very narrow and small handlebars, and it fits perfectly. I couldn't go any bigger or it wouldn't fit.
Hope your trip is amazing- can't wait to see the pictures!!