Cranks (yet more)

There are so many threads on cranks. Would someone point me to step by step instructions for removing and installing them?

Many thanks,
Raphael Lasar
Matawan, NJ

what kind?

Fair enough. I want to put these on my 29" uni.

Thanks again,
Raphael Lasar
Matawan, NJ

this is proabably not the best way, but i have instlled and removed this brand crank now quite alot (for me). i use a rubber mallet to hammer each one on, and a socket wrench to tighten the crank nut. upon removal i plce the uni on a work bench place a chisel or punch through the spokes and on to the back of the crank close to the axle and hammer it off, usually one BIG hit is all it takes, they are robust cranks and cheap so i dont care if i damamge them.
my mate brought his crank puller round once and that worked muc better, and probably was healthier.

I use this to remove the cranks:

It works great, but the problem is that I have to remove the pedals for it to work.

If I were to do it over again, I’d get this instead:
For this one, you don’t need to remove the pedals, but you do need a pedal wrench to turn it since it doesn’t have a handle.

Another option I was thinking of was to cut down the handle on the first one so it’s short enough to not need to take the pedals off.

To put the cranks back on, I use a 14mm socket. I normally don’t need a mallet. Be sure to have some grease on the spindle and the threads.

Hope that helps,

I just put em on dry, tighten em down with a 14. make sure they’re tight as I go on the first ride or two (more if necisary). sometimes, I use a mallet after tightening the cranks down, and then retighten. but not all the time.

Thank you all.

In fact, John Drummond talked me into buying one of these. I’m glad he did, because once I looked at it and the crank after getting the nut off, it became clear how it works. And it does work.

After getting the crank off, and being fairly pleased with myself about it, I took a half hour to play some ball with my daughter. I have run into enough complications trying to do what seem to be the most routine maintenance on my unis that I figured I’d enjoy the moment before tackling the task of getting the new cranks on.

I couldn’t find my rubber mallet, last used to pound into the ground a ghost on a wooden stake for Halloween, so I used the blocks of wood and regular hammer method. The first one went on easily and solidly, but it took a few tries to get the second one on so that I couldn’t shake it loose with my hand.

I trust it is on pretty well, but to be honest, I’m going to have a bike shop check out my work before the LBI Unithon. I’ve already had a crank come off once half way through and I don’t really want a repeat. This, of course, assumes they wont come off on their own before then.

I did not use any grease, but did apply some Loctite Blue. (Why does that stuff come in very red packaging?)

In any event, as I know many here experience on a regular basis, there is no small amount of satisfaction in being able to do your own work. I’m glad I made the effort.

Now I just have to get used to riding the 125mm cranks on my 29er. Quite an adjustment. The speed is great; in fact, it is a Coker like feeling. The freemounting, idling, and hills are another matter. I’ve had enough initial success that I know it’ll be comfortable in time, but I was somewhat surprised by the big difference in the feel.

So, thanks again.

Raphael Lasar
Matawan, NJ

There should be no mystery to this. Buy a crank puller. I went to my local bike shop and bought one for under £10. It’s easy to use. If it isn’t obvious then the person at the local bike shop will explain it to you.

Never mind rubber mallets, grease and Loctite. Just do the job carefully.

It’s a simple 5 minute job.

My procedure for installing cranks has changed now that I have a torque wrench. I now consider the use of a torque wrench to be critical for ensuring that the cranks are installed correctly. The torque wrench eliminates a lot of guess work and uncertainty.

My procedure for crank installation:

  1. Buy a torque wrench. See my thread I’m torqued for a recommended $20 torque wrench.

  2. Rub some grease on the hub tapers. Be careful not to get any grease on the hub threads because the threads are going to get Loctited. Grease and Loctite don’t mix. The grease will prevent the Loctite from sticking correctly and doing its job.

  3. Put the crank on the hub. There are three ways you can go about doing this. In most cases option “a” will be enough.
    a) Press them on by hand with no mechanical aid. This should be adequate for most cranks. However, some cranks may not slide willingly all the way on to the taper. In these cases a little mechanical persuasion might be needed.
    b) Pound the cranks on using a block of wood and a rubber mallet. Do not pound directly on the crank with a mallet or hammer. You may damage the crank. Place the block of wood on the crank and then use the rubber mallet or hammer to tap on the block of wood.
    c) Use a large C-clamp or bar clamp to press the crank on the taper.

  4. Put some red or blue Loctite on the crank nut. Either the red stuff or blue stuff will do the job. The red stuff is the high strength or permanent strength Loctite. The blue stuff is the medium strength Loctite.

  5. Thread the crank nut on with your fingers.

  6. Tighten the crank nut using a torque wrench. Tighten the nut to 35 to 40 foot-pounds. It is important that the nut be lubricated with Loctite to get a consistent and reliable torque reading. If the threads are dry you may get an unreliable torque reading.

  7. Install the dust caps.

With this procedure the cranks should be tight and not loosen up on you during a ride.

Park Tool has a nice FAQ item on removing and installing square taper cranks. Park Tool crank FAQ It includes some pictures and shows a torque wrench being used to tighten the crank nut.

You can have your local bike shop make sure that your cranks are tight. Just have them use Loctite on the crank nut and then use a torque wrench to get it tightened to 40 foot-pounds and you’ll be all good for the unithon. The bike shop may look at you a little weird for making such a request. Just let them know that it makes a difference with unicycle cranks.

It is weird that blue Loctite comes in a red container. The blue refers to the color of the product and not the color of the container. What’s even more weird is that the red Permatex threadlocker comes in a blue container. Permatex is the same stuff as Loctite, just a different brand.

John, do you use anything on the other side for reaction force? I lay the uni on its side with the other crank on some wood (weight taken by the HUB end of the crank), then put a block of wood on the top crank as you describe and deal a few hammer blows. After that I turn it around for the other crank, even if it received some force already while being at the bottom.

Tired of having to remove the pedals (for lack of a high enough block of wood), I made this little something to put under the wheel hub. Now it’s high enough so that the pedal can stay on. The strangely shaped metal parts (which I bent from regular 90 degree hooks) are mounted under tension so that if the wood gets compressed after some use (or shrinks somewhat from drying out), there is still firm contact between all three parts. Otherwise it wouldn’t be effective for counter force.

Klaas Bil


Another shot. Ready to receive the hammer.

Klaas Bil


I don’t usually use the mallet and block of wood technique. When I do I don’t have anything on the other side other than my legs. I’ll stand the unicycle up and use my legs as support on the back side of the wheel. You only tap on the crank. You don’t pound on it so the forces are not that great.

I usually us the bar clamp method. I use a bar clamp made by Bessey and press the cranks on.


Re: Cranks (yet more)

On Fri, 30 Apr 2004 01:33:45 -0500, “john_childs” wrote:

>You don’t pound on it so the forces
>are not that great.

That must be ‘you’ as in ‘I, John Childs’, because I, Klaas Bil, /do/
pound on it. I figured that if using a heavy press (rather than a
C-clamp) is a good method to press on cranks, they need quite some
force. I’ve found that if I just tap the cranks on, then tighten the
nuts more or less properly, then pound the cranks as I described, I
can tighten the nut more without using more torque than in the first
round. That makes me conclude that the pounding is required for
properly mounted cranks but maybe I am wrong? Maybe I deform

I don’t have a torque wrench. At the few places I checked they were
horribly expensive. Specific buying recommendations made by USAans
(like you, recently) don’t help for this European. I guesstimate the
exerted torque by multiplying the effective wrench length with a
guessed force - for the latter I try to think a %-age of my weight, a
bucket of water etc. Very imprecise but it’s at least something.

Klaas Bil - Newsgroup Addict

Clearly a system of 1/14 and 1/16 is not decimal - Mikefule on the English weight system

With grease on the tapers the cranks should slide on fully without too much pounding or too much pressing force. But some cranks have weird tapers and don’t seat well, so extra force is needed for them.

If you’re using aluminum cranks then the crank taper may be deforming as it is pressed on and the nut is tightened. That could be why you’re able to get more tightening after pounding on them a second time.

Take pictures of your torque wrench setup when you get it rigged up. I’m sure it will be interesting.

Raphael –

Give me a week or two notice, then come to Unatics, and I will give you a personal workshop on uni maintenance. We’ll cover the tools and all the little steps to make sure your unis stay tight and happy, and we’ll perform each step on whichever unis you bring. It’s even better to do it right away while I’m injured and can’t ride.

Persistence… :wink:

– Dave

Re: Cranks (yet more)

On Sat, 1 May 2004 03:04:20 -0500, “john_childs” wrote:

>If you’re using aluminum cranks then the crank taper may be deforming as
>it is pressed on and the nut is tightened.
I was mainly thinking of my UDC Max Traction with Bicycle Euro (steel)
cranks and a Suzue hub. The cranks have an ‘auto-ratcheting’ (©Harper)
feature as you may recall from a pic I posted some time ago. The
accompanying text is quoted in Mike Hinson’s sig.

>Take pictures of your torque wrench setup when you get it rigged up.
>I’m sure it will be interesting.
Why? A torque wrench is just a torque wrench (not mentioning the fact
that I have to immediate buying plan). The
pounding-before-torquewrenching setup is rigged up like that second

Klaas Bil - Newsgroup Addict

Clearly a system of 1/14 and 1/16 is not decimal - Mikefule on the English weight system

Re: Re: Cranks (yet more)

It sounded like you were going to rig up a home made torque wrench with a long cheater bar and a weight on the end. That would be different.

Kind of short notice, but a confluence of eventualites has occured that permit me to show up TODAY.

See ya.

Raphael Lasar
Matawan, NJ

Ak! Due to impending rain, I won’t be making it today… Since it’s a 6 hour RT I have to pick my attendance days. However, I’m sure that people there would love to see you. Contact David Stone, though, since there is a city-wide bike ride today.

Re: Re: Cranks (yet more)

As usual, Sheldon Brown has some useful advice.

Yes, that is what is happening. The shallow taper causes a huge mechanical advantage. For every unit of force used to push the crank onto the taper the square hole must react with a hundred times that force in stretching tension. Hammering is, by definition, a large impulsive force so in the instant of the hit the material around the hole is stretched with perhaps a hundred tonnes and permanently deformed.

This is bad because the deformations are concentrated at the corners of the square hole. At best the material yeilds uniformly, but to me this is highly unlikely. Rapid application of force causes ductile materials to behave as if they were brittle, so what might have been a relatively benign uniform stretch is probably a series of micro-cracks. This significantly weakens the crank hole, and worse, makes the hole “softer” and less able to resist pedaling forces. A crank so damaged is likely to wobble and come off. (The band-aid fix for a crank damaged in this way is called lock-tite.)

The best approach is to start with brand new, quality cranks and NEVER pound on them. Bike mechanics routinely put cranks on that never come off by slowly stretching the crank onto the taper with a calibrated force. This is what the manufacturers recommend, and IMHO, it works really well.

I use the approach the Campagnolo tech rep suggested - clean, dry tapers, grease on the bolt threads, hand-placement of the cranks and a slow torquing - with a torque wrench - to the recommended tightness. I regularly apply FAR more pedaling pressure - both forwards and, in the case of my fixed gear bikes, backwards - on long, high leverage bike cranks than I ever would on my unicycle cranks and have never had a problem. (Then again, I’ve never bent a crank on a big drop either.)

This approach is better than nothing.

I sympathize, sort of - the German hardware stores I shopped at only carried the best stuff. There were no racks of cheap Taiwanese imports because the cultural norm in Germany is to only buy tools that you can proudly hand down to your grandkids. That value isn’t as strong over here, so we have a market for disposable tools.