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:
All multi-tools are not created equal, but most with a plethora of features will get plenty of the jobs done. I personally like, and use often, the Lezyne RAP-21 LED tool, which will run you around $30. I like it because not only is it a high quality construction, but it has just about everything you’ll need, plus a sweet mini light. This will give you a chain breaker, spoke wrench, disc brake wedge, and all the most often used Allen keys and drivers. We’re talking a decent number of tools for 1/4 of what they would cost buying them separately.
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.