If you’ve ever slogged up a steep climb all the while wishing you had just one more gear to lessen the pain in your legs (but don’t want to buy an entirely new drivetrain), then it’s time to explore the benefits of bike expander cogs, which just as the name implies, expand the gear range of your existing cassette.

To understand how bike expander cogs work, if first helps to look at the inner workings of a bike cassette. Each one is actually a group of cogs (think machined wheel of metal with teeth that engage a chain), and each of these cogs represent a gear. As a general rule, a smaller cog (with fewer teeth) it is harder to pedal, while a larger cog (with more teeth) it easier to pedal, which is especially handy when tackling tough climbs.

And while some cassettes are made from a single block of metal (and thus not convertible using bike expander cogs), many others consist of multiple pieces than can be swapped out. And that is where bike expander cogs come in. If for example your mountain bike is outfitted with an 11-40 Shimano XT or XTR 11-speed cassette, but you wish you had an easier gear, then the OneUp Cassette Expander Cog Kit is a viable option.

Simply take off 17t and 19t cog on the existing Shimano cassette, replace them with OneUp’s 18t and 45t, and voila you’ve expanded the range of your drivetrain by a not-so-insignificant 12.5%. At the same time, the new 18t cog helps maintain even spacing between gears as you shift up and down the cassette, lessening drastic (and typically unwanted) changes in cadence.

This is just one example of the many possible “expansions” of today’s current cassette line-up. To learn about other options or check compatibility, give one of our expert Gear Advisors a call at 951-234-7554. They can walk you through the decision matrix, assuring you get the added range you’re looking for.