Rain covers for all Bihn backpacks sound like a great idea.
Alosaks...Navy Seal approved...will tote most things and are water proof. Available in various sizes at Amazon. If we are talking standing in a downpour....Alosaks and/or a travel umbrella (the latter of which will not be utile while riding a bike).
The stockpile keeps growing...I'm in serious trouble.
Nothing new here after all these years, *sigh*...
'Still Raining, Still Dreaming' #TheJimiHendrixExperience
(-; double right click any part of the video window to loop! ;-)
I'd love a rain cover too! I bought my Brain Bag for university last winter, and we did have a fair amount of rain. My things were fine inside, but from now on I'll be carrying a laptop, so extra protection is something I'd be interested in. I've read the thread and will be searching through the links posted to find something, but if TB ever offered their own, well, I'd have to get one.
I'm planning to try this one:
Sea to Summit Ultra-Light Packcover - Small - REI.com
It's made for internal frame backpacks, so I don't know how well it will stay put around a Brain Bag, but it does have some adjustability so it's worth a try.