Before getting to this week’s tip, you may recall that a few issues ago in RBR Newsletter Issue No. 770, we provided tips on using CO2 pumps. Those are the small inflators that work almost like gas station compressors thanks to utilizing compressed carbon dioxide gas.
Since that article, we received a promo on an interesting new product from the innovative German company SKS. Their Rideair portable air tank works like a CO2 pump. Yet, instead of relying on carbon dioxide gas in small replaceable cartridges, it has a cartridge that you fill with air from any regular bicycle pump. The tank fits into a bottle cage. Then, when you flat, this nifty pump has enough compressed air to fill your tire fast – and even seat tubeless tires. And you never have to pay for cartridges. Learn more: http://www.sks-germany.com/en/products/rideair/
Getting those rings squeaky clean
It’s important to clean your drivetrain regularly because chain lube picks up dirt and debris from riding. If you keep logging the miles and ignore it, the build-up of grime wears the chain and sprockets more quickly.
It’s relatively easy to clean the chain, rear derailleur pulleys and even the cassette cogs on the rear wheel. All it takes is wiping these things clean with a solvent-moistened rag (or commercially available bike wipe). For the cassette cogs, remove the rear wheel and slip the rag in-between the cogs using a shoe-shine motion to clean them. Depending on how greasy everything is, this wipe down might take a little while, but it’s not hard to do.
The component that can be hard to clean is the crankset. As the drivetrain gets worse, the grit and grime travels in between the chainrings and down behind the crankarms and spider (the “fingers” on the right crankarm that the chainrings bolt onto).
You can use the same solvent-soaked rag to clean between the rings. And you can use it to wipe behind the crankarms. Or you can try a brush. But it usually makes a mess of the frame in the process and doesn’t result in a like-new spic-and-span crankset.
An easier way
So, another approach that works a lot better and can be done on most double road cranksets is unbolting and removing the chainrings to clean them and the crankarms. Here’s how to go about it.
NOTES: These instructions are for double road cranksets – ones with two chainrings. If you have a single-ring crankset (a 1X system – say “one-by”), it’s easy to clean that one ring since both sides are exposed. If you have a triple crankset with three rings, there may be more bolts and spacers. You might still want to take it apart, but work carefully so you don’t mix up or lose the small parts. And you might find that the only way to remove the small chainring is to remove the crankarm from the bike.
There are a few cranksets that are difficult to disassemble. If upon inspection it isn’t obvious how to remove the chainrings from your crankarm, you may have one of these models. If so, you’re better off wiping or brushing it clean than trying to take it apart. Another option if you have the tools is to remove the crankarm and clean the assembly off the bike.
Tools & materials
You’ll need the correct tools to remove the chainrings, which is done by removing the chainring bolts. Look closely at the bolts that hold the rings onto your crankarm. On many cranksets, each bolt is composed of a male and female half.
On Shimano Hollowtech cranksets, the bolts are hidden on the back side for a clean look. And they are individual bolts.
Chainring bolts will be either 5mm and/or 6mm bolts requiring hex wrenches in those sizes (some cranksets use bolts with 5mm and 6mm heads – front and rear half). Or yours might take a T30 torx wrench if you have a newer crankset (6-point star-shaped pattern).
For the cleaning, round up an old toothbrush, solvent and rags. And for reassembly, get a little grease for lubricating the chainring bolts.
Mark/record the chainring orientation
Important: before taking anything apart, be sure to record how the rings are currently positioned on the bike because chainrings normally only fit one way. If you put them on in the wrong position or upside down, it will affect the shifting, or might even cause the chain to come off.
Many rings have indicators built into them that clue you in how they are installed. But it can take experience to know what you’re looking for. So it’s a good idea to mark the parts with an indelible marker before taking the rings off. Take photos, too, for reference.
If you have black rings and only black markers that won’t show up, you can put tape on the rings and mark that. Just be sure not to lose the marks when cleaning.
Start by lifting the chain off the small chainring and resting it on the frame. Then using the appropriate tool(s), turn the chainring bolts counterclockwise to loosen and remove them one at a time. Pay attention to how the bolts go back into the rings and crankset because once they’re all out, it’s easy to forget.
Also, be careful. Sometimes the bolts are tight and if they suddenly loosen, your hand can run into the chainring teeth. As you remove the bolts, put them in a safe place. You don’t want to drop and lose any (they tend to bounce and roll under things) or else you won’t be able to put the crankset back together until you find the right bolt.
Another caution is to be sure to fully insert the Allen or torx wrenches into each bolt as you loosen them. Many cranksets today have aluminum bolts, and if you don’t fully engage the tool, it’s possible to partially strip out the hole, making it much harder to loosen and remove the bolts.
If you find a chainring bolt that just turns and won’t loosen, look at the back half of the bolt behind the small chainring. Often there’s a slot in that inside bolt that you can fit a small flat screwdriver in to hold that half in place. That will allow loosening the chainring bolt on the front side of the crank. Or your crank might have Allen chainring bolts on the outside and inside, which is a nice feature.
Removing the chainrings and cleaning
With all the bolts out, you should be able to remove the chainrings from the crankarm. The outside ring will come up and over the crankarm. The smaller one will need to be wiggled past the spider and then up and over the arm.
Once off the crankarm/bike, the chainrings are actually fun to clean because you can inspect and see every bit of grime on every surface of the ring, both on the front and back. You can soak the rings in solvent if they’re a real mess and then clean them with the toothbrush.
After degreasing them, use clean rags to wipe off any remaining gunk and get them clean and dry. Don’t miss cleaning in between the teeth, the valleys between each pair. That’s where the chain runs, and if you don’t get this clean it can make the drivetrain feel crunchy when pedaling.
Lastly, be sure to inspect and clean the crankarms. The toothbrush will be handy for cleaning recesses and cutaways behind the right arm and spider that tend to collect grit and grime.
Putting the chainrings back on is easy, but take your time and follow your marks and/or photos to ensure everything goes back exactly how it came off. There is often a chain-catcher pin protruding from the large chainring. That goes right behind the chainring. For small rings, there’s often a small lobe on the inner edge of the ring that’s lined up with the crankarm.
Be sure to apply a little grease to all surfaces of the chainring bolts (both halves and the threads). That’ll ensure you get them tight and make it easier to get them off the next time you do this job. Also, it help prevent any annoying clicking when pedaling.
If you have a torque wrench, tighten steel bolts to 12-14 Newton meters (Nm) and aluminum ones to 8. Don’t overtighten aluminum bolts or they can break.
Now enjoy that sparkling clean crankset! It’s a good idea to do one final chainring bolt tightness check after the first ride just to make sure they’re holding fast.
Jim Langley is RBR's Technical Editor. He has been a pro mechanic and cycling writer for more than 40 years. He's the author of Your Home Bicycle Workshop in the RBR eBookstore. Check out his "cycling aficionado" website at http://www.jimlangley.net, his Q&A blog and updates at Twitter. Jim's streak of consecutive cycling days has reached more than 8,000. Click to read Jim's full bio.