Any recommendations for a bicycle backpack which can be easily clipped on a bicycle tray in the back?
Ortlieb bags seem pretty good in my experience. I have the backroller XL which is a pannier bag with a shoulder strap rather than a backpack. Plus they are made in Germany and not just a German company with outsourced production.
Can also vouch for Ortlieb. Back when I bike commuted to the office, I used an Ortlieb single pannier for my laptop and accessories. Was pretty convenient to clip my bag to the bike and not get my back too sweaty from riding with a backpack.
Yeah, as a former sweaty back commuter its a big improvement to not have a backpack on. Plus I get fewer holes in the back of my t-shirts now from friction between them and the backpack.
Although with the heatwaves right now I still get fairly sweaty, at least not having a backpack on makes it a bit better.