9. How To Replace Cotterless Crank Arms
Crank removal and installation procedure on a square-spindle, sealed bottom bracket.
IMPORTANT: Nuts and bolts on your bike should always be tightened to the manufacturer's specifications.
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VIDEO UPDATES
- 02:08 - The crank bolts should be torqued to about 35 foot-pounds, or 420 inch-pounds.
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 35 foot-pounds, or 420 inch-pounds.
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.
Recommended Books:
- Zinn & MTB
Mountain Bikes: Maintenance, repair, and troubleshooting. - Zinn & Road
Road Bikes: Maintenance, repair, and troubleshooting. - Sutherland's Manual
Sutherland's handbook for bicycle mechanics on CD-ROM. - Park Blue Book
Hundreds of photos and hundreds of procedures.
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41 Responses to “How To Replace Cotterless Crank Arms”
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and oh, if you have a maintenance/repair question, please ask in the help forums.
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- Shimano TL-FC10
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The MW-SET includes 6mm to 15mm box/open end wrenches. - Park Adjustable
Big & powerful adjustable wrench. Jaws open to 36mm. - Essential Tool Kit
Includes tools needed for many basic adjustments and repairs. - Starter Tool Kit
11 genuine Park Tool products & a custom Park Tool toolbox. - Advanced Tool Kit
The AK-37 includes all the most frequently used tools.
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.
OK. That was the easy part.
Now where is the chapter on [old] cottered crank arms? Park Tool no longer sells their CR-2, and I’m still loathe to use a hammer. Also, where can on get replacement cotter pins for crank arms?
Thanks.
Status of this Request
Hello Alex, excellent site, great tips and instructions. I have a question relating to cranksets. I want to change mine from a 22/32/42 to a 28/38/48, but since my chain rings are riveted I need to replace the entire crankset. My bottom bracket is 120 mm. How can I maintain the correct chainline? Will I also have to replace my BB? And what about my front derailleur, will I have to change that too? Thanks.
Take the crankset to your local shop and get them to match it with a replacement. If they can match it up you shouldn’t have to replace the bottom bracket or front derailleur, but you might have to make some minor derailleur adjustments.
Thanks for the tutorial. I just re-greased my bottom bracket. When reinstalling the crank the drive side is now too close to the frame and the chain-ring rubs against it — I didn’t neglect to re-install any washers or other parts. Any idea what my problem is?
Stan, I’m guessing the spindle is backwards. Both ends of the spindle are usually different lengths. Try pulling the BB apart and flipping it around. Let me know if that works.
Great tutorial Alex. I just replaced the cranks on my Schwinn mountain bike. The cranks were fine, but I had a crash, which stripped the threads which accept the pedal on the right crank. Wasn’t too upset since I had just replaced the rear gear cluster, and now have all new gears front and back.
One thing I noticed, was that when I replaced the right crank, I had to replace the left as well. The lengths were identical, but the square bracket was cut differently in the old cranks versus the new, so that instead of 6 oclock and 12 oclock, the new right crank and old left crank were at 12 and 8. I just replaced the left side with the replacement that came with my new set, and the angles were correct. Unexpected, but something to be careful of for anyone needing to replace only 1 crank.
Thanks again Alex,
Justin
Hi, awesome tutorial!
What brand/model crank puller did you use? I used a very similar (if not identical) one at my local bike co-op. They mostly have Park Tool tools.
However, when I look at the Park Tool website, i don’t see the same crank puller. They have ones that come with a handle. I like the one you used because it saves a lot of space.
Thank you,
Joe
Thanks Joe,
In the video I am using the shimano crank extractor, which does work great for this job!
Tutorial was very useful except I have a problem. I followed it to the letter but when I inserted the crank puller it encountered no resistance at all, and when it was fully extended the cranks were still on. I took both bolts off and saw it to be completely hollow all the way through the BB and spindles, so there was nothing for the crank puller to push off.
It’s not a cheap bike, Specialised Hardrock with Suntour cranks and a cartridge BB of unknown manufacture (I haven’t been able to take it out to have a look), nor is it old (8 months old, but it’s been trail riding pretty much every weekend since I bought it)
I’m having the same problem as jonb, specialized hardrock sport with suntour cranks. Not getting any resistance from the crank puller! Mine is a 2010 hardrock!
The Park Tool crank puller has a small donut held onto the non-business end of the tool with an o-ring. Remove this donut and place it into the business end of the tool before threading it into the crank. There is a shoulder on the spindle that matches up with the diameter of the donut. The puller will work as advertised used in this manner.
I am also having this issue with the exacting the Suntour SR crank from my 2008 HardRock. I am using the Park Tool CCP-22 crank puller. When attempting the extraction I have no resistance. Am I using the correct tool? Can you recommend a wrench that will work for me?
I was having the same issue as JonB. Turns out I was using the wrong tool. Use the Part Tool CCP-44 crank puller. It works perfectly.
hey. i was wondering if the Truvativ Hussefelt cranks are cotterless cranks? thanks.
Hi Kyle,
Yes those are cotterless!
The torquing comment about “use your arm strength” can lead to bad things. Remember at 12″ from the socket head or equivalent (ie: the center of the nut bolt or screw) 10 lbs. equals 10 ft.. lbs. . Consider using a 12 inch handle/wrench and a weight, you can use common items and check their weight on a bathroom scale. if the weight is small, weigh it with yourself, then weigh yourself, and subtract the difference. The inaccuracy in this method is way less. You can alternately use part of your body weight, estimating off the top of your head, just don’t lunge on the wrench, momentum increases the force dramatically. 6″ length you double the weight or force, 24″ length cut it in half, etc.
Thanks Robert, good advice. I’ll do a tutorial on torque and tightening. Right after I made this video I realized the mistake and added common torque specs in the text just below it (video updates).
Thanks for all your tutorials. Really clear and precise guidance.
Thanks also, and your welcome. I could have been a little clearer on the later points, but brevity took precedence.
I have another problem, the bearing cup on the non-drive side was apparently installed with a press, rather than a wrench!! I have some metal working skills, but if the lower bracket housing is gouged up inside, I may have to build up and re-machine the interior of the housing. I know machine shops that will do the actual work, but I’m not sure it will be necessary, and the frame is aluminum, I suspect it has a steel insert inside the bracket housing.
Turning the adjustment bearing cup was only accomplished with a hammer and cold chisel. 15 minutes of beating on it rather seriously moved it half a turn, and back again, same effort, after removing the lockring and trying the proper “Park Tools” wrench you use in the video Any pertinent info, as to thread chasers for the bearing cup threads inside the housing or sleeve inserts for the bottom bracket would be helpful. Its a very nice low priced frame, and I’m an ex VW home mechanic turning bicycle hobbyist, so nth degree efforts on this are a likely out come just to conquer the “beast”, and for edification.
Keep up the good work.
Hi Robert,
You can get the threads chased. Your local bike shop may have the tool. Much better to pay them a few bucks than buy the tool yourself… they run around $300-500.
Thanks again, keep up the good work!