Chainrings

A chainring is a front sprocket, specifically of the type that would attach to the crank by being bolted on to a spider.

When should you check your chainring for wear? What should I check for?Check for wear whenever you replace your chain. There are three things to check for:

1. Checking wear on chainring teeth:
   
   • Wipe the chainring down and inspect each tooth. The teeth should be straight and uniform in shape and size. If the teeth are hook-shaped, the chainring needs to be replaced. The chain should be replaced as well because a worn chainring accelerates wear on a chain and because a worn chain causes hook-shaped teeth in the first place.
2. Checking wear on chainring bolts:
   
   • Check that the bolts are tight by turning them clockwise (usually with a 5 mm allen wrench). If the nut one the backside turns, hold it with a two-pronged chainring nut tool or do it carefully with a screwdriver.
     [Remember, chainring bolts can be different in that some will take a star-shaped TORX T30 tool instead of a 5mm hex key and others take a 6mm hex key for the nut on the backside]
3. Checking for trueness on chainrings
   
   • Look down from above and turn the crank slowly to see if the chainrings wobble. If they do wobble, make sure there's no play in the bottom bracket. It is possible to fix small, localized bends with an adjustable wrench but if it's really bent, replace it.
     [Note: It is normal to have a small amount of chainring wobble and flex when you pedal hard, but excessive wobbling will compromise shifting
     If you've installed a new chainring and still see serious back-and-forth wobble, chances are good that the spider arms on the crank are bent]

How to replace chainrings

1. Remove the right crank
2. Before moving your largest two chainrings you'll usually need to remove the smallest one as well, which is often threaded directly into your crank. Use the allen key to loosen all the bolts that hold the chainring in place.
3. Note the position of the chainring in relation to the crank before removing it completely. Sometimes chainrings have a bump sticking out that should be lined up with your crank.
   
4. The largest two rings are usually held together with a nut and bolt. First note their positions relative to the crank and after removal, remember the order and number of washers in between them.

Chainring Installation

1. Apply a thin layer of grease to the threads to keep out moisture
2. Reassemble your chainrings the same way they came apart with just your hands
3. Thread on all bolts finger-tight and then use your allen key to tighten them all in a star pattern, repeating this pattern until all bolts are tight (but don't overtighten)