Dropped $180 on a waterproof backpack liner and it made my 7 mile ride in the rain feel normal
I bike 7 miles to work in Portland and got tired of showing up with a soaked shirt because my cheap bag leaked at the zippers, so I bought a $180 roll-top liner last month. Turns out keeping my work clothes bone dry is the whole game, and I stopped needing to stash a backup shirt at my desk. What is the one piece of gear you finally paid up for that fixed your sweatiest or wettest commute problem?
The liner is probably doing the heavy lifting, sure, but the leak point on most cheap bags is the zipper itself more than the fabric. A roll top with no zipper at all on the main compartment is really what fixes it, since water gets pushed through the teeth on a standard zip over a long wet ride. Your mileage may vary by bag though, some zippers are taped and sealed and hold up fine for years.
A zipper can be the weak spot for sure, but acting like the zipper is the whole problem kinda misses the point. Cheap bags leak from everywhere, the seams, the fabric coating breaking down, the roll top closure itself if you don't fold it right. Spending more on a roll top with no zipper but junk materials just moves the leak somewhere else. And a good taped zipper on a well made bag will beat a cheap roll top any day in my book.