Road Bike Cranksets
Cranksets receive more abuse than any other part of the bicycle. In short, cranksets are responsible for 100% of the power transfer from a rider to the bike. All of the energy you produce must go through the crankset to produce forward momentum. As you might imagine with a part so crucial to the performance of the bicycle, manufacturers offer a seemingly endless array of cranksets, all claiming to improve performance. In reality, only so much can be done to improve a crankset, so here is our attempt at cutting through some of the marketing noise to help our customers pick a crankset that suits their riding style.
While manufacturers continuously claim to reinvent the crankset, they remain fairly simple components. Cranksets are composed of three primary parts: Cranks arms, chainrings and a bottom bracket. The first two items are fairly self explanatory. Bottom brackets are the cartridge that fits into the frame itself and houses the bearings that facilitate the pedaling motion.
When you purchase a crankset, you are essentially getting crank arms with chainrings attached. Bottom brackets are sometimes included, but that varies from brand to brand. Chainrings are removable and can be replaced when worn, which generally takes several years. Differently sized chainrings can also be swapped out, though sizes are limited by the size of your crank arm spider, which we'll get to when we discuss compact cranks.
A good crankset should be light and stiff. That said, bike parts are generally ruled by the 2/3 rule. Pick two: light, durable (stiff), cheap. It can be light and durable, but not cheap; if it's durable and cheap, it's not light, etc.
Carbon vs. Aluminum
As with pretty much all bike components these days, high performance cranksets can be made from aluminum or carbon fiber. Generally speaking, carbon cranks run a bit lighter than aluminum, while aluminum cranks tend to be more rigid. Campagnolo and SRAM both make high-end carbon fiber cranksets that they swear are as stiff as any aluminum crank, with buttery-smooth performance and, of course, the lightest weight you can get in a crankset. If weight savings is your number one priority, by all means pick up a Super Record or Red crankset.
That said, these manufacturers' aluminum cranksets also deliver great performance, and in many cases are not all that much heavier than their carbon fiber counterparts. In fact, Shimano's high-end Dura-Ace crankset is comparable in weight with SRAM and Campy's offerings, despite being made of aluminum. Yup, Shimano remains the last holdout in the carbon crank wars. They maintain that they won't produce a carbon crank that would lack the stiffness of their super-strong alloy cranks. But even lower-end aluminum cranks will serve all but the most competitive cyclists very well. The mid-range lines of Shimano, Campy, and SRAM all include excellent and well-engineered alloy cranksets.
Most every crankset will get the job done. Lighter cranksets will tend to be more expensive. If your main concern is durability and stiffness, go with aluminum. If your goal is a light, sexy, eye-catching ride, carbon cranksets will get you there.
Triple vs. Compact
Traditionally, recreational and touring riders often chose a crankset with three front rings rather than the standard two. This provides more low end gears for comfortably getting over climbs, while maintaining a 53-tooth large ring for powering across the flats. We do carry triple cranksets, and triples are useful for touring riders carrying large loads, but for the average rider, triples give a much wider gear ratio than necessary and add quite a bit of weight. Enter compact cranksets.
Compact cranksets have provided one of the more useful component innovations in the past decade. Essentially, compact cranksets provide smaller, easier to push front gears. Standard cranksets typically provide 53-teeth and 39-teeth front rings while compacts utilize 50-34.
But compacts provide much more than just "granny gears". With proper cassette selection (usually 11-23), compact cranks actually provide more "useful" gears than standard cranksets. While powerful pro's and competitive racers rely on their 53x11 gearing for intense sprints, most riders have little use for anything above a 53x14. Compact cranks provide a wider range of the small and mid-range gears used in climbing and tempo riding, with a sacrifice of only the largest gears. Compact cranks provide more efficient gearing and generally weigh less than standard cranks, and much less than triple cranks.
There is one significant mechanical difference between standard and compact cranks. It lies in the length of the crank arm spider. Crank spiders are measured by BCD, the "bolt circle diameter". Standard cranks utilize a 130mm BCD while compacts use a 110mm BCD. For the most part, chainrings fit one or the other size, not both, though Shimano, for one, is trying out a proprietary spider design that fits both standard and compact chainrings, but only theirs. Compact cranksets may also utilize a special front derailleur, though many derailleurs are compatible with both compact and standard double cranksets.
We highly recommend compact cranks to all but the most accomplished racers. Compact cranks provide versatile gearing where you need it most, reducing muscle fatigue and making your ride more comfortable. Feel free to contact us at [email protected] or 1-800-651-4050 with any questions regarding crankset selection and compatibility.