my kh hub/axle interface was loose. i could tell because the cranks dd not move independent of each other, but would move together when bolted down hard. Me and ObieOne fixed it, and so far it seems to be holding up like new! After a lot of thinking, some throwing, twisting, hammering, fumbling, and drinking of mountain dew, came up with the idea and way to take the axle out of the hub (without destroying everything). he used a block of wood and a hammer to knock out the axle, then hammered it back in in a different position. Everything is solid, and once again problems are solved at 3 am with a lot of soda and hammering.
You should have put some Loctite 660 Quick Metal retaining compound on the axle while you had it out. The Loctite will make the fix last longer. If you have problems with the axle slipping again, do the Loctite fix.
As you discovered, it’s an easy fix to do.
We didn’t have any loctite better then red ( 
) on hand.
His slop was pretty bad, so I came up with the idea of replacing the axle in a new position so that the hub body in order to move some of the gaps in the keyways around. Anything was better then how it was; he had a ton of slop (prolly like a cm…he could also move his axle side to side 3 inches).
I just hammered directly on the axle because I knew I wouldn’t miss. It came out easily enough. When I went to hammer it back in I started by hammering a piece of wood but the wood quickly became a gigantic 8 spline crank so I hammered for a couple on the axle. It was going in slower then it came out, which I took as a good sign. I gave it to Nick and, of course, he hammered a couple spokes by accident. We finished up and everything was rock solid and silent.
The loctite green would definately have been better, but this seems to be holding up nicely. If it starts slipping again we can repeat with the loctite.
Anyone can do this. It is very easy. Just be careful if you opt to hit the axle directly. I only did it because I knew I wouldn’t miss (carpenter).
The Loctite 660 Quick Metal retaining compound or green 620 retaining compound will be better than the red Loctite threadlocker for this application. The retaining compound is designed to fill larger gaps and hold better than the threadlocker. The 660 stuff will be harder to find. I went by one auto parts store today and they didn’t have it. If I looked around some more I’m sure I could find it. The 660 stuff will fill slightly larger gaps than the 620. The 660 stuff is also thicker, it’s a paste rather than a liquid.
I also recommend using the Loctite primer to clean off the parts and to accelerate the curing. The primer also helps to ensure a stronger bond. The parts need to be really clean before applying the Loctite. That means no grease, no oil, no film, and no dirt. If the parts are not clean they will not bond as well as they should.
I don’t recommend pounding directly on the axle with a metal mallet or hammer. The axle is softer than the hammer and you can deform the end of the axle by hitting it with a hammer. If you deform the end of the axle too much you might not be able to slip the crank back on because the splines will be mushed like the head of a mushroom.
It would be better to thread the axle bolt in snugly and pound on the axle bolt instead of the bare axle. The axle bolt is harder, and if it gets damaged it can be replaced. Be sure to anti-seize or grease the threads of the axle bolt before threading it in. Pounding on it can be a bit brutal to the threads and could damage the threads if they’re not anti-seized.
Here’s how I pounded out my Profile axle: Dissected Profile Hub. I threaded on the Profile crank tool and pounded on the crank tool to remove the axle. That’s pretty much what the Profile crank tool is designed for. I also anti-seized the threads on the crank tool before threading it on the axle. The directions with the crank tool mention the requirement to anti-seize the threads before pounding on it. Profile will not warranty the axle if the threads are damaged because the crank tool was not anti-seized.
This is actually a fairly easy repair for a hub with axle slop and doesn’t require too many special tools. Many people could do it themselves. The alternative is to send the hub/wheel to Bedford or Unicycle.com and have them fix it.
I’ve been riding a KH 24 for a couple of month now and it has the same problem. Thanks for the “loctite trick”, my reseller will make it as soon as he gets the Loctite.
But I’m I the only who thinks it’s not normal, given the price of those unis? My reseller bought 2 KH 24 and 1 KH 20 they all have the same problem!! 
It isn’t right that the axle is slipping after only a short period of use. That shouldn’t happen. But it did. There was a batch of hubs made where the quality control was not good and there is a lot of hubs in that batch that have axle slop. That’s one of the risks with manufacturing in China or Taiwan. It’s harder to control quality. If the hubs and unicycles were made in Canada or the US it would be easier to control quality and the manufacturing process, but the cost would be much much more. The KH unicycles are less expensive because they’re made in Taiwan. Compare the cost of a Profile hub to the KH hub and you get an idea of the kinds of cost differences. The Profile hub is made in America. The KH hub is made in Taiwan.
The way these hubs are made means that there is always the possibility that axle slop will develop after some use. The axle is just press fit inside of an aluminum hub body. Press fits require very tight tolerances (tolerances of just a few thousandths of an inch). If the parts are manufactured just a little out of tolerance then you can get axle slop. If the parts wear down during use just a little bit you can end up with axle slop. My Profile hub developed some axle slop after a couple of years of use. It’s something that can happen to these hubs given the way they’re made. Press fits and keyways are not going to hold forever.
To get better long term reliability we’ll have to move on to some different designs for the hubs. For now, the current designs are the best we’ve got. We’ll have to see how future designs compare.
What if the flanges go on like cranks http://gallery.unicyclist.com/KH_style_hub from http://www.unicyclist.com/forums/showthread.php?s=&threadid=33494&highlight=made+a+hub .
Kris Holm just posted that’s the way his kh/onza hub are going to be just with more splines and with a whole outer hub body. At least thats how I read it.
Yes, that is one of the future designs that I had in mind when I said we’ll have to see how future designs compare. There are other ways to improve the hubs too.
The problem is that you cannot weld steel to aluminum. So if you use a steel axle and an aluminum hub body (or aluminum flanges) you have to figure out some other way of fastening them together. The current way of doing it with a tight press fit and keyways is not the most robust. There is room for improvement.
I’m curious to see how the Koxx-One hub is put together.