Your Mountain Bike Chainrings, which are an essential part of your bike’s drivetrain, may get worn down over time. You’ll notice wear in the opposite direction that the chain travels, and they’ll start to look like shark fins.
Extreme wear may cause your chain to slide from one ring to another, or you may have “chain suck,” which is when the chain does not release correctly from the teeth on the chainrings, causing the chain to get entangled and potentially broken.
All these indicate that it is now the appropriate time to replace the chainrings.
To remove your chainrings, you may or may not need to take the complete crank out of the bike, depending on how your bike is set up. This post will concentrate on how to replace your chainrings without removing the crank from your bicycle if that is possible.
Browse the assortment of Mountain Bike Chainrings available at REI.
Equipment and Components Necessary for Altering Chainrings
Determining the sort of chainrings you have may be difficult, as can purchasing new chainrings and switching them out. There are many different bolt designs for chainrings, and the one you need depends on whether your bicycle has standard or compact gear and whether it is a road bike or a mountain bike.
Some chainrings, referred to as “direct mount”, do not have any outside bolts; instead, the chainring attaches directly to the crankarm and is kept in place by the form of the lockring. On certain bicycles, the chainrings may even be an integral part of the crankarm; in this case, the whole component will need to be entirely replaced.
When it comes time to replace your chainrings, the kind of chainrings you purchase will be decided by the number of bolts that hold your chainrings to your bike in conjunction with a mathematical formula based on a measurement known as the bolt circle diameter (BCD). Get the assistance of your trusted bike technician in calculating your BCD so that you may choose the appropriate components.
Tools: Your bike’s chainrings are fastened to the crankset using several bolts, and because there are a variety of nut and bolt combinations, you will need various tools.
You will virtually never be able to get by without a chainring nut wrench, designed to work with a certain kind of nut known as a chainring nut with a slotted channel that runs through the middle of the nut. In addition to that, you will want either an Allen (hex) wrench or a torx wrench.
There is compatibility between the chainring bolt and the chainring nut wrench.
Taking Off your Mountain Bike Chainrings
Find the appropriate tools, such as a chainring nut wrench, a hex or a torx wrench, and make sure they are compatible with both the bolt on the rear side of the chainring and the chainring nut on the outside of the chainring. When you get your wrenches in position, crank the nut on the front to loosen it while maintaining the bolt on the rear in its original position. After completely removing the chainrings, set aside the nuts and bolts so that you may use them with the new chainrings. Next, slide the chainrings onto the crankarm of your bicycle.
(Whenever you find that you cannot finish this step, you will need to remove the whole crank, which requires additional tools and techniques that are not covered in this article.)
Putting on the Chainrings on the Bike
When replacing chainrings, you must effectively remove them and then replace them in the opposite order, beginning with the biggest ring.
Put the chainring on by sliding it over the crankarm. The chainring’s brand name should be oriented so that it is facing away from the bike, and the chainring’s ramped edges should be oriented so that they are facing toward the bike (toward the bike). (When changing to the next chainring, the “ramps” assist guide your chain in the proper direction.)
Large chainrings often come equipped with a pin or tab to prevent your chain from being caught in the space between the chainring and the crankarm. Adjust the chainring such that the pin extends out from the main frame of the bicycle and rests behind the crankarm.
First, apply lubricant to the bolts, and then reinstall the bolts and nuts using the same tools that you used to remove them. However, don’t tighten the bolts and nuts all the way to their maximum capacity. After the installation of all bolts and nuts, give each bolt a quarter turn of the wrench and continue moving around the ring until they are all snug. After that, check each one with a torque wrench, being sure to tighten it according to the manufacturer’s instructions.
Adjust the chainring’s bolt tension.
After reattaching the chain to one of the chainrings, test the functionality of the bicycle by peddling it manually while ensuring that everything is in working order. If you’ve altered the size of the chainring that sits outside your primary chainring, you may find that the height of your front derailleur has to be readjusted.
Browse the assortment of bike chainrings available at REI.
Bike Chainring Maintenance
You should definitely give your chainrings a thorough cleaning at least a couple times each year, depending on how often you ride. Please visit our article on “How to Clean a Bike” for additional details.
Keep a closer watch on the state of your whole drivetrain if you live near a beach where sand may enter your drivetrain or in a damp area where rain often washes away your chain lubricant, causing your chain to rust. Sand can get into your drivetrain and cause it to malfunction, and rain can routinely flush away your chain lube, making your chain rust.
Make sure you read our article on “How to Change Your Bike Chain” to get familiar with the process of changing your chain, as this may frequently delay the need to replace your chainrings.