While you might expect to use an Allen or Torx key to replace a Shimano Direct Mount chainring, that’s not the case with Shimano. Shimano’s 12-speed drivetrains feature a direct mount chainring system. This means the chainring attaches directly to your crank using a locking ring.
The beauty of this direct mount chainring setup is its swift interchangeability. Whether you need to replace a worn-out chainring or switch to a smaller one for mountain climbs, swapping is a breeze.
Shimano wouldn’t be Shimano without requiring an additional tool for this job. In this article, I’ll walk you through the step-by-step process of replacing such a chainring and explain the required tool.
What tool do you need to replace a Shimano Direct Mount chainring?
To loosen the locking ring of a direct mount chainring, you’ll need the following special tool: Shimano Direct Mount Tool TL-FC41. Alternatively, you can also use the LRT-4 Lock Ring tool from Park Tool
Shimano Direct Mount TL-FC41
In addition to this tool, you’ll also need an adjustable crescent wrench or large spanner to use the tool. Most people typically have such a wrench at home. However, ensure that the wrench you use has an opening of at least 32 mm.
Whether or not you decide to acquire the Direct Mount tool is entirely up to you. However, it’s important to note that you won’t be able to replace your Shimano chainring without this tool.
If you have a SRAM chainring and crankset, you won’t need a special tool. A SRAM 12-speed chainring is also of the direct mount type, but it’s attached with 3 Torx bolts.
This might be something to consider if you choose between SRAM and Shimano when purchasing a new mountain bike. Over the years, I’ve noticed that you often need extra tools for Shimano.
How do you replace a 12-speed direct mount chainring from Shimano?
Aside from needing the extra tool, it’s quite easy to use, and replacing your direct mount chainring is a breeze.
To access your crank with the chainring mounted on it, you’ll need to first disassemble your crankset. Here’s how:
- Loosen the 2 bolts from the left crank.
- Unscrew the lock nut from the crankset (Shimano TL-FC16 tool).
- Disassemble the crank arm.
Caution: do not lose the plastic piece that fits between the gap in the crank.
Once you’ve accomplished this, you can pull the right crank and axle out of the bike. A gentle tap with a rubber mallet might do the trick if you encounter difficulty. If you use a regular hammer, use a cloth to prevent damage to your components.
You can use the direct mount chainring tool once the crank is completely out of your mountain bike. This is not at all difficult and can be done by anyone.
Tip: During a thorough cleaning of your mountain bike or just as a routine maintenance task, it’s wise to loosen the chainring using the direct mount tool. This ensures that when you do replace the chainring, it will come off easily without any issues.
In the meantime, you can clean it and apply a fresh layer of assembly paste. This will ensure that you can easily and quickly loosen the direct mount chainring locking ring every time.
Removing a 12-speed direct mount chainring.
The Shimano TL-FC41 tool can’t be placed incorrectly on the locking ring of the chainring. Just make sure the teeth interlock to ensure the tool is properly positioned.
To loosen the chainring, place your adjustable wrench on the tool. The easiest way to start is when the crank arm and wrench are parallel. This allows you to turn the chainring counterclockwise with the wrench while firmly holding the crank arm with your other hand.
Due to the opposing forces exerted by the wrench and the crank arm, the locking ring should usually come loose easily. If this is not the case, a bit of multi-spray can help. The first time I loosened the locking ring, it came off immediately and with minimal effort.
Once the locking ring is loose, you can continue turning it. You’ll notice that it has some threading. Unscrew the locking ring until it’s completely loose. After that, you can remove it from the axle. The chainring is now completely free and can be replaced.
Caution: When removing the chainring, you’ll notice a plastic spacer/seal ring between the chainring and the crank. Be sure not to lose this.
How to mount a Shimano 12-speed direct mount chainring?
When you’ve purchased a new chainring, you’ll notice that you only receive the chainring itself. You’ll need to reuse the locking ring each time. Also, don’t forget to reuse the seal ring; hopefully, you haven’t misplaced it.
Take advantage of the opportunity to thoroughly clean everything while your chainring is off. Some parts are difficult to reach when they’re mounted on your mountain bike. So, take full advantage and clean everything nicely now that everything is disassembled.
Mounting the chainring is just as easy as disassembling it.
The chainring can only be mounted in one way. Just like with the cogs on your cassette, one larger notch on the chainring allows you to attach it to the crank in only one orientation.
You can now apply a bit of assembly paste to the thread of the locking ring. This will help it come off smoothly next time. Then, place the locking ring onto the chainring and hand-tighten it.
You’ll need the Shimano direct mount tool and your adjustable wrench to secure and tighten it fully. If you’ve looked closely, you can see how tight the locking ring should be. It’s recommended to tighten it to 35 to 50 Newton meters.
Since I don’t have a torque wrench with such a range, I’ll need to rely on my own judgment to determine when it’s tight enough. Similarly to tightening the cassette, I’ll tighten it based on feel rather than using a specific torque measurement. Up to now, I’ve never encountered any issues using this approach.
Tighten the locking ring with the adjustable wrench while holding the crank arm with your other hand. Always keep the following motto in mind: “Tight is tight,” and don’t overtighten it.
Important tips
If everything has gone smoothly, you can reassemble your cranks. Before hitting the road with your new chainring, it’s important also to check the wear of your chain, cassette, and derailleur pulleys. When replacing one component, it’s advisable to replace the others as well. This has been my practice for years, and it helps prevent unwelcome surprises on the road.
If you plan to use chainrings of different sizes, for example, a smaller one for mountain biking in the Ardennes, it’s wise to regularly mount the smaller chainrings so that all components wear evenly.
Final thoughts
By diligently following the guidelines in this article, you should be able to replace your direct mount chainring without any issues.
It’s not difficult at all, and anyone can do it themselves. However, you will need a few extra tools, which I showed you in this article. Besides the Shimano Direct Mount tool, you’ll also need a tool to remove the crank.
With the help of these tools, this step-by-step guide, and your common sense, replacing a direct mount chainring becomes an easy task that takes hardly any time at all.
Please do let me know if you succeeded by leaving a comment below.
