Man, if you're starting out and you know you'll need several components for a bag... just get this. It will save you so much time picking everything out that even if you balk at the price (amazing value, by the way) I bet that if you did the math using your hourly wage and the time spent picking everything out and making sure it fits... you'd save a lot of money and a lot of irritation if you just got this. Just get this.
Mini Pump:   This actually goes on the frame of your bike, as it’s a bit too big for most under-seat bags.   Coming soon, we’ll have a review from Bill of his very favorite one, but a good pump is a lifesaver.    Some people instead carry a CO2 inflator, which is faster and easier to use but does require disposable cartridges, and each time you have a flat, you’ll need at least 2 of those cartridges.  There are combined pump/inflator tools that we’ll also talk about soon.
If you own a bike, you need a flat-fixing kit. It’s really that simple. Sure, maybe you’ll get lucky and get a flat close to a shop, or the buses will be running on time for once, but even with all that going for you, getting stranded across town will cost you time, money, and precious sanity. You can put together a great kit in less time than it takes to read this guide.
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.
For the budding mechanic:  A good pocket sized repair guide.   One good option is the “Pocket Guide to Emergency Bicycle Repair”  by Ron Cordes and Eric Grove.   It’s only 3.5×4.5 inches and a half inch thick.   I don’t carry this myself, but for someone who’s new to this whole bike repair business, it’s really helpful to have. A future blog post will cover this book in detail.

Friction gear systems are a lot simpler to adjust, because the movement of the derailer cable can be modulated as you ride, every time you change the gear- they require less cycle maintenance. Modern index shifting systems are a little more complicated because each ‘click’ must release the exact right amount of cable to allow the derailer to move the correct distance to move the chain from one gear to another. Setting up and adjusting a derailer is not difficult and requires only basic tools, but there is a methodical procedure to follow.