Topeak Tri DryBag
This top tube bag sits just behind your stem and provides enough space to fit plenty of nutrition and a small-sized mobile phone in (it used to be fine but they keep making phones bigger). It has a waterproof top layer that does a good job of keeping your stuff dry.
The inside is soft-lined, so you won't scratch anything, but would also make it difficult to clean if you got it dirty. It is quite tall and you may find your knees occasionally knock into it, so it is not quite as good as having integrated storage on the bike.
We use a simple one, two or three star rating system. One star for stuff we do not like, two stars for gear that is okay and three stars for equipment we recommend. We awarded this product 3 stars. All reviews and ratings represent our opinion only.