Dubbed 'Straggle-Check' frame bags, these bags are designed to fit both 700c and 650b Straggler and 700c Cross Check frames. Size up one size on your bag if you've got a 650b Straggler frame and voila, it fits. These are handmade by Revelate Designs in the U.S., made of Dimension Polyant VX 21 polyurethane coated fabric. It's durable, rip resistant, tightly woven and laminated to make it highly water resistant but not fully waterproof…. Revelate advises using stuff sacks inside (such as the one in which our bags are packaged) if you risk riding in extended downpours or underwater.
Surly's Straggle-Check frame bags (as well as their mountain bags) are now using a ladder strap system, which allows greater flexibility in how you attach the bag to your frame. The ladder straps let you customize the fit and placement of the mounting straps so if you have some weird contraption clamped to your frame tubes like a chain keeper, cable pulley, or some trinket grandma gave you, it won't interfere with the mounting straps on the frame bag. They're also including foam bumpers for the mounting straps to minimize thread abrasion to the bag and attachment points
Quality YKK brand water resistant zippers – with an improved, water resistant zipper 'garage' – control compartment access and help keep the weather out. Zippers are sewn with a stretch panel to relieve stress on the zipper as well. Stress even kills zippers. The large main compartment has a flexible divider inside, and there's a hydration port to make sure your whistle stays wet. There's also a compartment suitable for smaller items you'll access relatively often, like your map, phone, hard boiled eggs, uncontained pudding, marbles for playing marbles, your dugout, that ring you found that makes you disappear when you put it on, or whathaveyou.
Frame bags such as this are light and reasonably voluminous. They are stable because they center weight low between your wheels and body, and they go places where racks and panniers are often troublesome, like singletrack.
Note: due to the rough texture of the mounting straps, prolonged use may lead to scratched or worn paint. If you're worried about keeping everything looking pristine you probably ought to look for some other type of bag, or figure a way to protect the paint, such as duct tape, or tatting a top tube doily - for example.