This is determined by the quantity and size of the accessories you want to transport.
A saddlebag can hold around 0.4 litres.
A handlebar bag generally holds between 2 and 6 litres.
Frame bags hold around 1 litre.
There's a difference between water repellent and waterproof .
If a bag is water repellent the fabric will ‘pool’ water on its surface, and the faster water runs off without soaking through, the higher its water repellency.
Waterproofing is the fabric's ability to prevent any water – whether that’s rain or snow, dew or water vapour – from penetrating it, therefore keeping the contents of your bag completely dry.
All B’TWIN bike bags are water repellent. However, only some of them are completely waterproof, so be sure to read each one’s description.
Compatibility with Smartphones/Tablets
Most people don’t want to be far from their phone or tablet, whether that’s for entertainment purposes, so you can call home or upload pictures from your ride to Instagram, or even so you can use it as a satnav, so it’s important to choose a bag that can carry your tech safely.
Look out for frame and handlebar bags with a specific transparent compartment for carrying and using your smartphone or tablet when you are on the move.