The crankset is the key part of the bike that converts physical human movement into the rotational power you need to get your bike moving. Your success and enjoyment will depend on your performance. To upgrade or maintain, you first need to know what it takes to make a great crankset; the cranks, spiders, chainring, shell, bottom bracket and axle each have a role to play. Here’s some terminology to get you started.

Crank Arms: These are the essential arms that connect the bicycle pedals to the spindle or axle. The bicycle’s left crank is usually bolted to the end of the spindle. The right crank arm can be attached in a similar fashion, but these days, quite often, it is permanently mounted to the drive-side spindle and spider.

Buy cheap if you’re a casual cyclist, but if hopping curbs and climbing steps is your passion in life, the shock of reconnecting with the pavement will exert great force on the pedal-crank and crank-spindle interface, so invest in weapons quality.

Spider: These are the star-shaped arms that radiate from the right crank to hold the front sprockets, or “chainring.”

Chain ring: A fancy name for the front sprockets. Different manufacturers, just like cars, design them with various bolt patterns, so identifying what specifically will work with your crank-spider-axle and front derailleur combination is essential.

Bottom bracket shell: This is the tube welded to the lowest point of your bike frame designed to accept a bearing assembly and the main shaft (bottom bracket assembly). It is usually threaded to accept the bottom bracket assembly. English, French and Italian bikes are NOT the same diameter or threaded to the same tpi (teeth per inch) so it’s important to get the right mix. It’s not really part of the crankset, but you need to know its specs to be able to replace any component.

Bottom Bracket Assembly: This bike part comes in numerous combinations and configurations, but the essentials include the driveshaft, a set of bearings, and cups that thread into the housing to hold all of these parts in place. This setup allows the pedals to spin freely and puts power to the chain.

Spindle: The last piece of the puzzle is the driveshaft. It comes in several different configurations depending on the linkage between the crank and the spindle. It may or may not be independent of the bearing set. On two-piece cranksets, it is attached to the right arm of the crank. Bottom bracket cups and bearings are sold separately to match the diameter and length of the axle.

Where buying a complete crankset gets confusing is that these 7 key pieces (2 cranks, spider, chainrings, spindle, retainer cups, and bearings) are not always sold the same or have a set of sizes.

It is essential to know what specifications are necessary so that repairs and upgrades can add speed and reliability to your driving experience. Read more on the myWheelsAndMore.com website for information and lots of pictures that will add clarity to this article. Find out what you need to know and why and how bicycle part suppliers and manufacturers continue to tweak their crankset designs to increase weight, durability and speed.