A wrench that fits the hub nuts: If your bike has quick release front and rear wheels, you don’t need this, but if you have an internal hub on the back, such as the NuVinci, a wrench that fits is a great idea. 99% of the time, this is a 15mm wrench, but you should check your bike. A 6 inch adjustable wrench can also work, but it will be heavier, and when using an adjustable wrench, you do need to take more care to not round over the nuts. A fixed wrench is the best choice. Some multi-tools have a 15 mm wrench built in, but again, if you have limited hand strength, something with more leverage is a great idea.
Unlike floor pumps, most hand pumps do not have pressure gauges. To get readings during my original round of testing for this guide, I built a special rig involving simple hardware-store parts. But the experts I spoke to seem divided on the usefulness of gauges. Half thought they were unnecessary, added bulk, and drove up cost. Why do you need a gauge if you know 100 pumps inflates your tire? But the other half liked them, because the “thumb test” is notoriously inaccurate.
I bicycle to and from work to save gas. I don't have a fancy bike, it's just a Schwinn mountain bike that's comfortable and can carry me plus gear but I want to be able to do my own work on it. I needed a book that was simple enough for someone new to bicycle repair and maintenance but could take me through all the upkeep my workhorse needs, and this book does just that. It's well-written and easy to follow.
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.