Don’t rely on others. “People need to recognize that now there are different cassette sizes, so there are different chains depending on what gear you have. A lot of people are like, ‘Oh my friend is always prepared they always have the stuff, I’m not going to bring anything.’ All of the stuff now is very bike-specific, and you have to have your own package of stuff.”
On the other hand, an on-bike repair kit will be a much smarter selection of tools that you are most likely to need. You should figure out the type of screws that are fitted on your bike and the things that are most likely to go wrong on a ride. Address only these things so as not to burden yourself too much with unnecessary stuff. Moreover, there are bike repair kits used on long rides and those used on shorter rides. The longer the ride, the more tools, and spare parts you will have to bring unless you want to have a very long hike back home.
These guys are awesome. After work, I got to my bike to discover my back tire was completely flat. It had a slow leak, so I was able to pump it up enough to make it to their shop. I got there 10 minutes before closing and they were able to fit me in. They replaced my tube and picked all of the glass shards out of my tire. Awesome customer service and they saved me from having to do this myself in the dark and the cold.
Our favorite hand pump for commuters is the Lezyne Sport Drive HP, and you can read more specifics about why in our full-length guide, written by Dave Yasuda, a writer and tester with over 30 years in the saddle. To sum it up, Lezyne makes pumps with an extendable rubber tube that connects to your tire valve, and that’s the difference between awkward and demoralizing. It’s not the only company that does so, but it is one of the few, and it does it the best. The Sport Drive HP can adapt to any tire valve, has no small fussy parts to lose, and inflates more easily to higher psi levels than anything we tested without floor leverage.
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.