To inspect your crankarms, grab and wiggle them toward and away from your frame. There should be no play. If you detect slop, find out if the cranks are moving on the axle or if the axle is moving with the cranks.
Take a look at the following simple crankset maintenance:
IF THE WHOLE THING IS MOVING and you have a sealed-cartridge bottom bracket, the BB is probably toast. Snug the retaining cup or ring, which might have loosened. The axle must spin effortlessly, or with some hydraulic resistance. If it feels or sounds dry, the diagnosis is correct so replace it.
If you have a used cup-and-cone bracket, try to get rid of the play with an overhaul before spring for a new BB. If you’ll need to remove the lockring at the left side using a special lockring-spanner tool, turn the adjustable cup counterclockwise to remove it. For this one, you usually need a special spanner also. Remove the dust sleeve, axle, and bearings (if you have one). Replace all the bearings, then regrease and reinstall them.
IF YOUR CRANKS ARE MOVING ON THE AXLE, you probably have a costly problem. Try snugging your cranks with a hex wrench, special installation-and-removal tool, or thin-wall socket, depending on the type of your crankarm. But if it’s the first time that you’ve checked for slop, your axle interface or crankarm is bent or deformed. In this case, you’ll have to replace one of both crankarms.
Snug up the chainring bolts using a 5-mm wrench. Check if there are any worn or bent teeth on the chainrings. Note that worn teeth look thinner and sharper. If you keep using a worn ring, it will wear your chain a lot quicker and be more prone to chainstuck. This will eventually wear the rest of the rings and cassette quicker.
But if you want to your chain to last longer, consider internal gear hub bikes. Internal gears protect the chain from dust, mud, and potential damages while riding.
Bent teeth can usually be straightened back. To do this, snug an adjustable wrench against the flat sides of the teeth and bend it back. But your chainrings are probably aluminum which means that you don’t get many chances to fiddle with the tooth. You should get it correctly the first time, otherwise it can snap off when you readjust it.
More Simple Crankset Maintenance
- Check your crank bolts once a month, and first three rides after an installation.
- Check for chainring wear every 1,000 miles.
- Check for BB slop every month.
Watch this video to learn more tips on cranset maintenance.