youngoldbloke
The older I get, the faster I used to be ...
I often use one of the Trek 'bottles', and it works well, but IME it is much better to use a saddlepack for tools, tubes etc, and the 'bottle' for phone, wallet, energy bar/s, keys etc. If on a longer ride I need two bottles, I use jersey pockets for waterproof, arm warmers etc. (I dont like carrying anything too hard or solid in the jersey - just in case). Muji sell a 'tarpaulin' pencil case that works quite well , but needs a strap (I use a toeclip strap) to keep it secure in the bottlecage. You can always carry a waterproof, or jacket, just rolled up in a cage, again with a strap to keep it safe. A 'Tribag' behind the stem is handy for wallet, phone, keys and energy bar, and you can also get double ones that hang over the top tube if you need more storage