Top tip, measure the size of what the items you wish to keep in your top tube bag, then look for a bag of that size. This was my choice - wallet, keys, and 2 nutrition bars. It also has a side pocket for change and is waterproof.
I’ve yet to hit my knees on it, and it shows no sign fading or wear after a Japanese summer withs its bright color fading sunlight. Excellent. If I was buying again I would see if they have a model with reflective strips.
A year after buying it all is well, which is impressive given the harsh summer sunlight here.
GORIX Top Tube Waterproof Bag B14 Amazon #Ad