Look around on your next mountain bike group ride, and you’ll probably see a mix of drivetrain setups. Some riders will be using single chainring setups while others will be pedalling double chainrings. In this article, we look at the advantages of each setup to help you determine which is better for you.
Wait, haven’t we be through this before?
Yes! The debate about the optimal number of front chainrings is not new. Mountain bikes used to come standard with a triple drivetrain setup including three front chainrings and a rear cassette.
However, as rear cassettes gradually picked up gears over time, growing from six to 11 in number, cyclists eventually figured out that they were pedalling around many duplicate gears and that they could still cover a similar gearing range with just two front chainrings – hence, the widespread adoption of the double front chainring setup.
Leading drivetrain manufacturers now offer as many as 12-speed cassettes as well as higher tech derailleurs that incorporate clutch mechanisms to reduce chain slap. Thus riders are again in a similar position of debating the pros and cons of eliminating one more chainring.
Advantages of a Single Ring Setup
It’s lighter. One less chainring and cable and no front derailleur mean your bike weighs less.
Shifting is simpler. You no longer have to worry about possibly dropping your chain when shifting between front rings. This is a big advantage, especially for racers shifting under pressure and for less experienced riders who lack confidence and skill to reliably use their front shifter with success.
It requires less maintenance. You’ll have fewer chainrings to replace when they wear out, and you’ll never need to adjust your front derailleur again during installation or as your cable would have inevitably stretched over time.
Cleaner cockpit. With one less shifter, your cockpit is less cluttered, and you free up one hand which can instead be devoted to operating your dropper post control.
Advantages of a Double Ring Setup
You have a larger range of gears. Because there are twice as many gears, it’s easier to spec them to cover a larger range. Having more gears at the low end makes it easier to tackle longer and steeper climbs. Having more gears at the high end means you can pedal down fast descents without spinning out.
Your pedalling may be more efficient. With twice as many gears, spacing between gears is typically smaller. If you are the kind of rider who is always shifting one gear up or down to maintain your optimal cadence, you will be more likely to always find the perfect gear at any moment.
You are more likely to have a better chainline. With two chainrings, you have more gear choices and can avoid poor chainlines, which means pedalling is quieter, requires less effort and causes less wear on your drivetrain.
Chainrings will not have to be replaced as often. Unless you always ride in just one of your two rings, normal wear and tear will be distributed over two chainrings, so you’ll have to replace them less often than if you were running one ring.
Do the Math
Still undecided? There is no substitute for sitting down with a gear calculator (such as http://www.sheldonbrown.com/gear-calc.html) and running the numbers on potential single and double chainring setups. Take the time to figure out your gear ratios or rollouts for your current and proposed setup. Then you’ll have a much better idea of how that potential new drivetrain will actually feel out on the trail before you invest the time and money to switch it.