Racktime Yves Bag Black 8x5.3x12.4in SnapIt

This feels very high quality on first install. It rolls open or closed very easily, and the long, flexible top allows you to roll it down fairly small (a little smaller than a bike helmet for an adult) to fairly tall (easily able to swallow a 12 pack of cans and a rolled up hoodie). The material and connectors feel very solid. The two inside pockets are very small (think cell phone or wallet) but also don't interfere with the main space. Highly waterproof. Expensive; only worth it if you already have a racktime rack.;

This is a great bag for my new electric bike. Holds a great deal and is weatherproof. Word of caution. Be sure to use a bungee cord or like to wrap around the bag and keep the top as low as possible. I have what is known as a boy's bike with the middle bar. When getting off the bike and swinging your leg over the back tire you can catch your heel on the bag strap very easily since it tends to rise up during use. A simple bungee cord took care of the problem. Electric bikes are heavy and easily tip if you are off balance.;