This tutorial will demonstrate how to remove and install square-spindled crank arms. I’ve based this tutorial on cranks attached to a sealed cartridge bottom bracket. I’ll cover the loose-bearing style in a future tutorial.
Tools Required
To remove the bolt, you’ll need either an 8mm allen key or 14mm socket wrench. To remove the crank arms, you’ll need a crank puller, a 16mm open-end wrench, and an adjustable wrench. If possible, a torque wrench should also be used for tightening.
Crank Arm Removal
In order to safely remove the right side, you’ll have to shift the front derailleur onto the smallest chainring, and then carefully remove the chain and rest it on the bottom bracket, so that it doesn’t interfere with the crank arm removal.
Using the crank arm for leverage, loosen and remove the tightening bolt with your allen key or 14mm socket wrench. Be careful not to skin your knuckles on the chainring teeth.
Before using the crank puller, make sure it is fully extended so that the internal driver does not extend past the external threads.
Note: If crank threads are damaged, there are a few solutions at Park Tools.
Carefully thread the external threads of the crank puller clockwise into the crank arm. Avoid cross-threading, which will damage the crank and prevent future removal.
Once the crank puller is fully threaded, place the adjustable wrench on the external flats and turn the internal driver clockwise until it stops. Turn the driver clockwise using a 16mm wrench, until the crank arm pulls free of the spindle. Repeat the same process to remove the left crank arm.
Crank Arm Installation
Before re-installing the cranks wipe both the square spindle and the crank’s spindle fitting to make sure there is no dirt or grease on either surface.
Now slide the right crank’s spindle fitting onto the spindle. Before installing the bolts, grease under the head and along the threads of both bolts. Thread the bolt all the way into the spindle threads and torque the bolt to about 40Nm (newton meters), or 305-390 in-lbs.
Set the chain back on the chainring and repeat the same installation procedure on the left side, making sure the crank arm is pointing opposite the right side.
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Nice site with simple, easy to follow videos on well chosen topics. One question, when tightening the bolts to the specified torque without a torque wrench how do you know how tight is tight enough? Is it possible to know this without a torque wrench?
Status of this Request
Hi Tuvok,
It is difficult to torque to the correct specification without a torque wrench. If you don’t have one, just tighten the crank as much as possible with your arm strength.
Hi
Your tutorials are excellent, but I have a question that wasn’t answered by watching your tutorials. How do I determine what size BB to buy for my bike? I have a Norco Shore 3 and I can’t seem to find the specs online. Could you give me some advice? Thanks once again for the awesome videos!
There are so many different sizes. The best way to determine the correct BB size would be to remove the old one and take it to your local bike shop for sizing.
Your tutorial on replacing cotterless cranks is fantastic. Do you plan on doing one for cottered cranks as found on vintage English 3 speeds?
Status of this Request
Thanks Gary. I do plan on doing a cottered crank tutorial as soon as I get an appropriate bike… although it may be a few months yet. I’ll let you know when it is posted!
Hello, my left crank arm shakes it’s self loose while riding, and if I don’t stop to tighten it, it falls off all together, doe’s anyone have any idea what could be wrong? and how would i fix it?
Hi Ian, it sounds like the square tapers where your crank arm attaches to the bottom bracket might be worn. Does the square tapered hole look rounded at all?
It’s slightly worn, but I only bought the bike a two weeks ago, so surely it shouldn’t have worn out so quickly? If I buy a new one is there anyway of preventing this happening again?
That is strange that it wore out so quickly, but if it was poorly installed to begin with it may have worn because it was ridden while loose. If you have to replace it just make sure the new one is tight enough when first installed, and stop riding immediately if it ever comes loose.
Oh ok, thanks, is a more expensive set of crank arms going to be more expensive because they’re lighter or stronger?
All cranks arms are strong enough to stay tightened. More expensive cranks will usually be lighter, but not always stronger.
Thank you.
Alex,
I am new to bicycling but it seems to me that the crank arms on my Cannondale System Six are too long. They are 175 and my inseam is 29. Do you believe 165 or 170 would be a better fit. I prefer a faster cadence and I currently find my legs too stretched in the down position. Lastly, are crankarms available seperately or would I need to purchase a new crankset? Thank you in advance and sorry if these questions are “bicycling 101″ type.
Ken
Hi Ken, it sounds like you might do well with shorter cranks, although it’s all personal preference. Sheldon Brown did a great job of explaining crank length here.
You can get crank arms seperately, but you may want to get them as a set so that the lengths match perfectly.
Hi,
trying to remove my cranks.
got the left off fine but having problem with my right.
its mega tight and my allen keys are just gettin churned up.
anyone know which way i loosen it? anti-clockwise or clockwise before i cross-thread and completely screw up my bike?
thanks
Loosen the right crank bolt by turning counter-clockwise.
I recently replaced a worn chain ring. After remounting the crank, at first I hadn’t tightened the bolt with enough torque. So there was a clicking noise when I pedaled. Then I tightened it up as tight as I could. But it still clicks when pedaling in all three chain rings. Before pulling the crank, it was silent. My bottom bracket is the kind with splines, so I was very careful during remounting not to damage them. What could be the problem?
Cheers
I know this may sound weird, but often the clicking noise is caused by dry pedal threads… try re-greasing the pedal threads
Thanks. That didn’t work, though.
I gave the restraining bolt another push. It tightened a fraction more. The clicking was then a lot softer. Is it supposed to be ultra-super tight? I’ve been using an 8mm Allen key. To loosen it, I had to return to the shop, where they used a 3 foot handle, with my leg pushing in the opposite direction. When I changed my drive from freewheel to cassette 2 1/2 years ago, I thought the mechanic had given it too much muscle.
Cheers
**By the way, good tutorials. They’re great for re-freshing memory on things that haven’t been done in a long, long time.