Owning a bicycle is a good idea, but taking care of it yearns for an experts’ piece of mind. You should not worry too much about taking your bicycle to a mechanic when you can handle the repairing on your own. It will rather save you the cost of every moment you get into a problem. Grab a pick of one of the toolkits from the above review. I assure you that, absolutely no day will you seek a mechanic for service.
Keychain style flashlight or headlamp, LED type, not incandescent: The keychain style is tiny and lightweight, the headlamp style is a bit bulkier but easier to use. You can get these for a couple of bucks or less at the local big box hardware store. The LED ones are lighter, more durable and last considerably longer. Very useful if you need to make a repair after dark! I keep a keychain style one as a backup as I normally have a headlamp in my backpack.
One key difference, that you can see in the photo, is that the BV uses buckles instead of Velcro on the straps that attach the bag to the underside of the saddle, something much more important than it may seem. A pair of bike shorts (or any shorts) will shred quickly if they’re rubbing against that tiny bit of Velcro protruding from the side of the bag, and it’s sure to destroy expensive sweaters and gym clothes if you stuff the bag into your backpack or messenger bag.
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.