A good patch will stick to your tube enough to keep air from leaking out. A great patch will act like a second skin and actually strengthen the tube where it’s applied, flexing and stretching with the tire. After 36 hours of testing, our official endorsement goes to the Rema TT 02 Touring Repair Kit. Its patches do everything other patches do, just better. The edge of the patch is also ruffled, which provides more edge surface area to bond—that’s a good thing.
Basic first aid supplies: A few bandages of varying sizes. 6 Aspirin, or other OTC painkiller of choice. A few alcohol pads in sealed foil packs, useful for cleaning grease off grease and grit off of the bike, and also cleaning cuts on yourself if you take a spill. 1 day supply of any prescription drugs you need to take regularly. Wrap these up in tinfoil and tuck away. It might just save your day.
The fabric attachment system is low-tech, but that seems to be helpful, as it can adapt to seat rails of different widths. One fancier option you might see on more expensive seat bags is a quick-release mount that you install under your saddle. But those have a fixed width, and therefore can fit under seats with only those exact specs. Brooks saddles, for example, are too wide for these mounts.
Modern bottom brackets use a sealed bearing type construction that keeps water and debris locked out, so they seldom go wrong. Maintenance is impossible so they need replacing when they do wear out. Older style cup bottom brackets need to be re-greased every now and again, and occasionally will need to have their bearings replaced. There are a lot more teeth on the chainring cogs than those on the rear cassette, so need changing less regularly. Cranks usually a solid one piece construction so there is not much to go wrong.