Whether it’s part of a service or to fit a new unit, knowing how to replace a crankset is a useful skill.
In this in-depth step-by-step tutorial, we’ll talk you through the process of removal and refitting for the four major types of crankset – Shimano, self-extracting cranksets (SRAM, FSA), Campagnolo and square-taper.
If you’re removing the crankset to replace the bottom bracket, it’s worth double-checking the bottom bracket you’re going to fit is compatible with your crankset.
How to fit and replace a Shimano crankset
Most modern Shimano road, mountain and gravel bike cranksets are comprised of two pieces, with the spindle bonded to the driveside arm. These are known collectively as Hollowtech II cranksets.
The non-driveside crank arm is fitted to the protruding portion of the spindle. This is clamped in place using an integrated clamp. A similar arrangement is used on Promax and FSA Gravity cranksets.
Shimano still produces three-piece Octalink and square-taper cranksets. The fitting removal process for these is covered later in this guide.
- 5mm hex key
- Torque wrench and 5mm hex socket
- Shimano Hollowtech 2 installation tool
- Rubber mallet
- Flathead screwdriver (optional)
How to remove a Shimano crankset
Shift the chain into the small chainring and smallest cassette cog. You could consider manually unshipping the chain and gently laying it to rest around the bottom bracket shell.
Evenly loosen the two 5mm pinch bolts. Loosen these off a little at a time – don’t undo one fully then the other. They don’t need to be fully undone.
Using a Hollowtech 2 installation tool, undo the Hollowtech cap (Shimano refers to this as the ‘crank arm fixing screw’ in its technical documentation).
This screw is proprietary with an eight-point star shape. Lift up the small plastic catch (Shimano refers to this as a ‘plate’) that sits between between the two pinch bolts.
The non-driveside crank should now remove by hand, although you may need to give it a light tap with a rubber mallet from the inside of the crank arm. Should this be the case, we’d recommend placing a rag over the inside of the crank arm for protection.
Take note of any dust seals that may come off with the arms.
How to refit a Shimano crankset
Refitting is the opposite of removal, but there are some important notes to be aware of.
To start, it’s worth giving the crankset a thorough clean before refitting.
Next, apply a thin layer of grease to the crank spindle, especially where it meets the bearings.
We’d recommend Shimano Premium Bearing green grease for best results, although you can use alternatives.
Feed the driveside crank arm through the bottom bracket shell, taking care to replace any relevant spacers or dust seals.
You may need to use a rubber mallet to fully seat the arm. Again, consider covering the face of the crankset with a rag.
Grease the splines of the spindle and install the non-driveside crank arm.
There’s a mark on the opposite side of the spindle with a hole to ensure the non-driveside crankarm is perfectly fitted 180 degrees apart from the driveside.
Grease the threads of the Hollowtech cap and install it into the non-driveside crank arm. Shimano quotes a low 0.7-1.5Nm torque.
If you over-tighten the cap, the crank arm will be pushed too far into the bearings, resulting in notchy operation. You can inspect your work by rotating the cranks to check if it’s too tight or too loose.
Press down the plate and equally tighten the two pinch bolts to 12-15Nm.
Before fitting the chain onto the chainrings, inspect for any play.
How to replace a self-extracting crankset
Many cranksets, such as those from SRAM and FSA, use a self-extracting design.
This enables the crankset to be removed without a crank puller.
The main crank bolt that secures the crankset to the spindle essentially functions as a crank puller when the bolt is loosened, in combination with a retaining ring. Therefore, only one tool is required to remove the crankset.
- Hex keys
- Torque wrench and appropriate socket
- Rubber mallet
There can be variations in which crank arm the main crank bolt is located. On SRAM DUB cranksets, it is on the driveside.
Regardless of which side it is on, begin by loosening the crank bolt.
The crank bolt can take quite some force to undo (especially on SRAM DUB cranksets), so we’d recommend keeping the chain on the big chainring to avoid skinning your knuckles. We’d also advise performing this step with the bike on the ground so gravity helps you.
If you’re finding it difficult to loosen, consider using a long ratchet handle or breaker bar for additional purchase.
You could consider using a toe strap to secure the non-driveside crank arm to the non-driveside chainstay.
Once the bolt breaks free, loosen until the arm slides off and away from the spindle. There will be a period when there is more resistance in turning the bolt. This is typical – keep going until the crank arm is free.
Take note of any spacers, wavey washers or dust seals that come off with the crank arm.
Remove the opposing crank arm – it may require some persuasion with a rubber mallet.