Originally Posted by
the sci guy
Already have a rack & pannier and for this commute & bike I prefer a pack or messenger bag.
I'm not here to second-guess your preferences or tell you what to do, but I'm genuinely curious: why do you prefer a backpack over a pannier?
If you want a backpack for ease of walking across the street to the YMCA but you already have a rack, maybe something like the Ortlieb Vario would be a good fit?