It’s just part of who we all are as performance-oriented riders. We want to squeeze every bit of performance from our bikes. Two ways we do that are by finding ways to add horsepower to the engine and by trying to reduce the bike’s overall weight to establish a more favorable power-to-weight ratio.
Why lighter weight is so great. If you’re a performance-oriented rider, there’s good cause to consider a weight-loss program for your bike overall. But where it can really count is in the bike’s drivetrain. It has to do with something called “rotational mass.” Rotational mass is the bulk of components in your bike’s drivetrain that rotate under power. Those include everything from the chain, the brake rotors, spokes, wheel rims, tires and, yes, your sprockets. The heavier each of those components is, the more engine power is needed to make them spin. Reduce the weight of those rotating masses and that translates to less horsepower being lost and more of it making it to the ground. Lighter-weight components, including sprockets, also contribute to more responsive acceleration and deceleration.
What are you made of? More accurately, what is your bike’s sprocket made of? Generally, sprockets are made of either steel or aluminum. Let’s look at the characteristics of each material.
Chances are, your bike came from the factory with steel sprockets fore and aft. The reason? Steel is tough, very durable, and provides excellent overall performance for the widest range of riding situations and needs.
Aluminum sprockets are significantly lighter – sometimes several pounds lighter than their steel counterparts. That reduction in rotational mass translates to better performance in the form of throttle response and usable horsepower.
Want to go fast? Not so fast! Before you jump to swap out those sprockets, you should know that there is a hitch. Performance isn’t free; to get, you’ve got to give.
Lighter-weight aluminum sprockets unquestionably deliver distinct performance advantages. But (and there’s almost always a “but”), aluminum isn’t as tough a material as steel and can wear significantly faster, especially when subjected to aggressive use. If you tend to put a lot of miles on your machine and have fitted aluminum sprockets, expect to have to replace components more frequently. Specially-treated anodized aluminum sprockets give aluminum a tougher coating and improve durability, delivering service life as much as 80% of steel sprockets in some instances.
For the rider who covers an abundance of miles each season and is not necessarily needing top-level performance, a steel sprocket does a good job overall and commonly lasts for tens of thousands of miles. The tradeoff is that steel is a significantly heavier material and, as we established above, that heavier material equates to greater rotational mass and, therefore, compromises in several desirable performance characteristics.
What’s the best next step? Why not explore the full range of sprocket materials and options available for your particular bike by visiting the SUNSTAR website at sunstar-braking.com. Need help selecting the right parts for your needs? Just ask! (add contact info)
Be sure to look for our next installment when we’ll look at ways to reduce weight further by changing to narrower chain and sprocket widths.