Little adjustments can often make the biggest difference, especially on a bike. Being able to tighten or loosen even just a single bolt can make a significant impact on the way the bike performs and how it feels, too. In order to make these changes you need to have a good range of tools at your disposal which often means wrenches and spanners in the case of cycling.
Bike spanners can help you to adjust everything from the position of the saddle to the crank and height of the bars; while bike torque wrenches can help you to tighten bolts into exactly the right position to ride as it should. There are even specialist pedal wrenches made for cycling, allowing you to make adjustments to the position of the pedals and to even upgrade your pedals to lighter or more comfortable versions.