Writer Peter Flax, the former editor-in-chief of Bicycling magazine, rode over 1,000 miles and tested 15 tools for our full-length guide to multi-tools, and he concluded the Topeak Mini 9 is the best for casual cyclists. It’s tiny, it’s light, it’s easier to get some leverage with than other tools that have different designs. It’s not meant for serious wrenching on your bike, but it’s good for on-the-fly adjustments.
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.