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.
I own the Lezyne CNC Chain Rod, which I’m a big fan of (yes, I know I’m partial to Lezyne here–they’re a local-to-me, San Luis Obispo company and they sponsored my collegiate team, so I got tons of gear) and it costs right around $30. But the truth is that even the cheapest of chain whips will likely do the job. In fact, I’ve found a dude who knows his stuff and shows you how to make this tool all by yourself. I would even go so far as to say that you probably have enough materials laying about your garage (if not, try your parents’ garage ? ) to put this together without spending anything. Check out the video below:
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.
Change and a $20 bill: In case your cell phone’s battery dies, it’s nice to still be able to use a payphone if you need to. Also, the $20 is a great thing to have in case you lose your wallet or have some other mishap. I’d rather be able to sit in a coffee shop or fast food restaurant when it starts raining while I’m waiting for my friend or cab ride, and a hot cup of tea or coffee or the beverage of your choice and a snack makes it all the more pleasant. Just try to remember, this is for emergencies, and if you use it, replace it ASAP!
Pedals are important because the serve as the contact point between the rider and the bike’s transmission. Clip-less pedals systems come in a variety of designs favoured by individual manufacturers, but the mechanics of all styles are roughly the same. Tiny adjustments in the position of the show cleat – that snaps into position on the pedal – can make a big difference to the comfort and health of the rider.