I've noticed no real correlation between riding position and type of bag appropriate for it.

I spent most of my life with an old-school one-strap messenger bag on a variety of bikes, ranging from 'holy **** instant back pain' to 'hey, nice apehangers', and it performed pretty much equally.

None of my current bikes have the stylish 3-foot drop from saddle to bars, but on my bikes set up 'eddy style', a backpack is working just fine as well. The backpack thing is still a bit new to me, and I find myself missing the convenience of just being able to swing the bag around, but that's more of an issue off the bike than it is on the bike.

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