Splined crank dilemma


Need advice to help me work with splined cranks.

KH29 with Onza hub, splined hub and 150 cranks. I bought and installed a Big Apple for road riding (it does fit after all) and after testing the new tire, went to install the KH 125 cranks I bought for road operations. Changed out the left side without problem. On the right side, I tightened up the crank bolt into the axle and put on the dust cover before installing the pedals. I noticed that the hardware on the right side of the hub was clanging around as if I had not adequately tightened the bolt–so I leaned on it again, no success to close the gap.

I called my son who is an avid cyclist who said that I may need to install spacers to make it fit properly. So, I went to remove the crank…now stuck with loose parts rattling on the axle outboard of the frame but inboard of the crank attachment. These parts on the left side are a relatively thick steel bushing that matches the inner race of the bearing, a large tapered washer that looks mostly like a mudguard, and a thinner steel washer just inboard of the crank arm. On the left side…it all snugs up properly. On the right, the crank arm doesn’t seem to seat all the way down on the splines (maybe 1/16" showing) and the hardware does not come up snug as I tighten the crank arm bolt. Need help.

How do I get the splined crank off the axle…my tapered crank puller won’t work ( I expect there is a specific tool for splined cranks, any special variant required?). Next, is it the norm to have to shim up tapered cranks to eliminate play in the inboard hardware?

Thanks in advance for your advice.


Hi Carey.
Sounds like you may have pulled your axle slightly off centre.To get the cranks off ( if they are like my o4 kh cranks) is to rotate the cranks horizontal so you see the head of the crank allen screw.Remove this screw,put a small shim into the slot at the rear of the crank.Insert the screw from the bottom and tighten until you hit the shim, now use an allen key to SLOWLY force open the gap.Once the cranks are off measure the axle each side to ensure it is central.Fit both cranks at the same time, fitting them loosely then tightening them alternately until you get the right tension.Hope this helps.

You are right to not ride the unicycle if you have not got the cranks fitted correctly. They will be damaged if you do.
As you son concludes it is imperative that on a splined crank system there is no movement of any of the spacers.
Here is a link to a drawing that shows the assembly order and the position of all of the spacers, this should help you with the assembly. No extra are required, but the order is critical.

For removing the cranks, just install the nylon washer and the extractor ring that were on the unicycle originally (look out that the extractor ring has a reverse thread on it). You then just remove the allan key bolt and this pulls off the crank.

The most commonly forgotten component when re-assembling the cranks is the “expanding spline lock ring” if you did not purchase any of these when you bought your new cranks you will need to use the ones in your old crank. A screwdriver will normally push this out for you.


No they are totally different and this can not happen.


oops.Thankyou Roger.Sorry Carey.

Crank problem


Thanks for your response. The method for crank removal makes perfect sense.

I went out and tried to back the axle bolt out with the reverse thread extractor ring. I got the axle bolt moving but was unsuccessful in getting the crank off (it is really stuck)–then the hex wrench slipped in the axle nut and rounded the edges…drat!

I am a bit disappointed as I told the people at UDC/USA exactly what I wanted to do (have a spare set of easily replaceable 150s and 125s) and my cranks apparently arrived without the necessary hardware. Sounds like I did not get the expanding spline lock rings you mentioned. Now I’m in a fix. I also was surprised to find upon disassembly of the 150 cranks that the two sides were not the same in terms of parts/washers and I spent a fair amount of time keeping them in order by side–doesn’t sound quite right. I’ll call them tomorrow, but I am stuck and I will likely have to send the whole assembly off to them to fix it. It is beyond my ability without tearing something up. Drat!

Thanks for your help. I did take it down to a bike shop for advice today and ran into a real Neanderthal who had an ugly “big hammer” plan that caused me to flee with my uni. Hopefully I’ll get the right help from UDC–I sure hope there is a way for me not to have to send it back, however. But, with the axle nut stripped and the crank in place…I’m probably hosed.




Oh this is not good, I am sorry. It is fixable, just not easy. You need to have the bolt drilled out, then extracted using a stud extractor.

I have had to do this several times and I have always succeeded without too much of a problem. So do not worry.

I am puzzled by the cranks being so locked on, I have not seen this before. It is possible that the extractor locked up, but this does not normally happen unless you miss off the nylon washer. A good tip when re-assemble the cranks is to apply liberal amounts of grease around the bolt to help keep it free moving.

Thinking about it, I have had one hub with a totally locked on crank, an old Onza which had been used in the sea rather too much and was rusted like mad. I solved that one by using a 3 legged puller and pulling the bearing off with the crank… not a good solution as it is very risky, if the bearing had collapsed I would have definatley lost both hub and crank.

The lock ring is not normally supplied with the cranks because in theory it is not needed. If you are just changing the cranks over, you take everthing from one set of cranks over to the other, so no problem. The reason we now sell the separately is that several people are switching cranks on a daily basis and want to leave one set in each of the sets of cranks. If the US don’t have the expanding lock rings I can get one to you from the UK within a week.


splined crank


I do have friends with the ability to do what you recommend. And, I believe that I could horse it off and get it to work. But, this is my brand new KH-29 and it is a disappointment to have this problem with the risk of damaging the unicycle–I plan to leave it to the pros. I am sure they will take care of this and do a good job of it. My problem is that I don’t know what right looks like as the side that is now stuck does not have one of those little washers under the cover because it did not come with one (the one on the other side did, however).

I plan to send this back to UDC/USA and ask them to fix it up along with proper configuration of both sets of cranks, so I can easily change cranks. Once they have it set up, I am sure I’ll have no problems. I will miss it for the time away, however. I do want it to be right. It was an expensive unicycle and I like it.