Square Taper & Octalink Crank Removal

You need special tools and the right technique to remove the crank from a square taper or ISIS/Octalink bottom bracket.

This video shows the whole procedure in quite a lot of detail.

The specialist tools you require are the ISIS/Octalink driver that fits into a half-inch square drive wrench. The best wrench to use is a torque wrench, since you will have to achieve a high torque within the minimum and maximum recommended torque settings.

You also need a crank puller which screws into the crank once the crank bolts have been removed. The simplest type to get a hold of is a basic unit without a handle. A 15mm socket, or 15mm wrench or a crescent wrench will be enough to turn the crank puller’s spindle. The spindle’s foot anchors against the bottom bracket spindle and slowly pulls the crank away from the spindle. It is hard at first but quickly becomes easy as the crank moves free of the spindle.

Replacing the crank, or mounting a new crank onto the spindle, does not of course require the crank puller. A smear of grease on the square taper section of the spindle is probably a good idea although there is a lot of debate about this. Long-time bike mechanics and enthusiasts swear that not putting grease on the spindles is quite ok—you just don’t need to grease them and, some claim, it will enlarge the aperture in the crank. They argue that the resistance from a non-greased crank won’t allow the crank to move too far up the spindle thus enlarging the aperture. An enlarged aperture being something you don’t want. Others argue that greasing the spindle will greatly reduce the chance of creaking in the future since there will be a small amount of movement of the crank against the spindle when a bike is being ridden. It comes down to personal preference based on who you listen to and your own experience.

The crank is moved into position through tightening the crank bolts which definitely need a smear of grease on them. The bolts can be tightened by hand with a shorter or longer wrench—a longer wrench will always make it easier. You will be able to get the crank bolts very tight but will still need a torque wrench to take you over the threshold of minimum torque. This will almost guarantee you won’t be out riding one fine day and have the crank come loose.

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