That didn’t exactly answer my question; if I don’t install the spacers, will the bearings move on the axle in normal use? It sounds from anecdotal evidence that the answer is “yes.”
Hey,
Thanks for the feedback, and thanks Roger for answering the key questions. To be clear, the 22/40 shimmed double bearing is a KH product not a UDC brand product, and has nothing to do with the Nimbus ISIS hub design. So - any critical comments should be at KHU not UDC =).
The primary intent of the 22/40 double bearing was to allow riders to retrofit an ISIS hub to a frame with 40 mm bearing housings, without needing to buy another frame. A theoretical side benefit could be that having double bearings each side could increase bearing durability by better resisting twisting forces during frame flex, but in practice the jury is out on that until they have been on the market for a while. In any case, that is a potential side benefit, not the primary goal. Wear or deformation of the shim should not be an issue as long as it fits properly; the shim is 7000 series Aluminum and should have adequate hardness & stiffness for this application.
Since they are intended for other frames not KH frames, it’s tough to suggest that they could make Moment or Nimbus ISIS hubs compatible with all 40 mm frame with 100 mm bearing spacing (probably they won’t!) but it should at least work for 40 mm Nimbus frames (they were tested for that).
Also, since this is an extremely niche product, even by unicycle standards, it’s design is restricted by the off-the-shelf bearings available. One could specially make 22x40 single bearings but I’d probably be a grandparent by the time I sold the first the production run.=)
I think that most questions have been addressed and Tom I know your comments are more general than your specific case, but nonetheless - can you make your setup work by simply filing the shims to fit?
Kris
I just wanted to chime in here and say that I have a Nimbus with an ISIS Hub and have no problems with it; the wheel spins quite freely. I suggest that you return it ASAP before you damage (even scratch) the unicycle.
Good question.
There’s a part of me that says yes, it would make sense to agree on a unicycle specific standard. As far as I understand it, the only benefit from using the ISIS bike standard is that we can fit a left hand crank on a unicycle (Or right if we don’t mind spiders). And as bike cranks are typically a lot longer than unicycle ones, there probably not a lot of times you would want to do that. If the standard can be agreed on, and works, and uses off the shelf components (ie bearings) where possible then it makes sense.
However, I know there has been a lot of time and money invested in changing over to ISIS in the last few years. We already have unicycles out there with cottered, square taper, 8 spline, 10 spline and 32 (or 36?) spline cranks so having another flavour on the menu will only make things worse. Plus, although we may not share the components in ISIS hubs and cranks with the bike world, the manufacturers already have their machinery set up to cut the splines to the ISIS standard so changing this now will add another layer of complexity.
STM
no, no, no, no…
ISIS as currently used on unicycles works. Apart from the R&D cost, time, inconvenience to & annoyance of riders, why change?
We’re not talking about computer software here!
But it keeps me in work!! lots more to design and things to sell!
Anyway what are you doing replying to this thread, you are too young! This is an old mans thread. 
i just got a nimbus hub from UDC (usa) and just laced into a new 29 inch wheel set. I did not get any spacers with my hub. So will my bearing slide or frame brake. What can I do to get spacers? Is it possible to make my own?
I don’t use spacers (and use 160mm bike cranks) on my Muni and have not had any problems. If you want spacers you could cut some tube to length or ask UDC for some, if they were suposed to come with the hub you should have goten them.
I would give you mine but I think I threw them out.
yeah i made my own from a cutoff of an old KH seatpost and they fit perfectly
My new Nimbus X ISIS Freestyle unicycle also did not come with spacers. Checking the UDC pictures it appears that most of the Nimbus ISIS hubs include spacers, but the 48h Freestyle and 36h Superwide intentionally do not. Why is this? And are the bearings transition fit or press fit on these two hubs?
So taking the advice here, and making my own spacers from a properly sized seat post I discovered that the Nimbus Lightweight ISIS cranks fail to meet the ISIS standard in that the distance from the lateral end of the internal splines to female shoulder measured about 15.7mm. ISIS standards require a minimum of 18.5mm. This means that the crank bolt will bottom out on the axle before the crank reaches the crank stop. Though not recommend, it is allowable by ISIS documentation to not make use of the crank stop; however, in this case the reason contact is not made is not from maximum required preload from the taper, but from the crank bolt hitting the axle.
These cranks bear the official ISIS licensing mark, which means that supposedly one of these cranks was sent to the ISIS Drive standard committee and was deemed to be in accordance.
I don’t know what to make of this other than that I will use my spacers to give me the standard 16mm spindle end to crank stop distance. For any aluminum cranks that do not reach this point I will let the cranks decide for themselves if they will creep or fret.
The more I read about crank standards the more frustrated I got at how complicated just sticking two things together can be.
I have a Nimbus X 24 from last year. When I got it, I noticed that the wheel wasn’t centered on the axle/hub. I rode it that way up until a few months ago when I decided to turn it into an offroad uni, so I got a big tire… Having it off center a few mm became a problem as the tire rubbed on the frame. Oh, I thought… maybe the dish is off on the wheel, so I redished and retrued the wheel and it still rubbed a tiny bit on one side. I began to take a closer look at the hub. There were no spacers and the bearings did not fit tight enough to keep the wheel centered, so I popped off the bearings and put spacers on the insides of the bearings. Fixed the problem. I just dug up a piece of steel pipe and cut off two small slices.
In my case the problem was one bearing pressed on farther than the other, so the spacers on the inside fixed that. Sounds like I should make two more spacers for the outsides too? well it’s been working perfect ever since so I’m not gonna mess with it anymore.
This is an interesting thread to find.
Just to follow up on my experience: unicycle.com agreed to ship me a new unicycle, this one with a 42mm bearing holder frame and 42mm OD bearings. The 42x22mm bearings address the most problematic issues I found: the spacers contact only the bearing races, so the wheel spins fine, and the outer race is steel, which doesn’t deform under unicycle use. I’m satisfied with the replacement, though not completely happy.
My conclusions are:
-
The KH bearing adapters which allow you to use a 40mm frame on a 22mm hub are not as good an idea as they sounded at first. The outer sleeve really should be steel, and the spacers need to be half the thickness to keep from rubbing against the bearing seal. (At half the thickness, the spacer may not be strong enough to act as the crank stop).
-
Regardless of the bearing size, the spacer mechanism used on the Nimbus ISIS hub is kind of hokey, and introduces dependencies which don’t exist on other configurations–notably, the tension on the crank bolt can affect the performance of the bearings, which isn’t true on any other ISIS configuration I can think of.
Wait till your bearing slips, then you’ll have the long walk out. I did it once, now I run spacers 
I have a number of differently sized spacers (2mm-6mm) depending on the crank and hub combo. No unusual wear on my spacers, though they do get stuck on sometimes. I use an automotive bearing puller to remove bearnings and a piece of pipe and a hammer to install them.
First off. A close up (actual photo) of the bearings would have nice. The only thing your video did was show the affect the spacer and bearing clamps had on the bearings. It did not show the damage to the bearings, and also did not show, in much detail, where the spacer was lining up to.
I am getting the impression that you would have been able to have a fairly well spinning, non slipping wheel by just removing the spacers.
However, it looks like your frame was creating too much inward or outward force on the double bearings. I have never used these double bearings, but from the description, it sounds like sideways force my be a problem… even tho they are supposed to handle it well.
One of the things I had the biggest problem with is, why you chose to take the wheel off with s screw driver. Your method of standing on the wheel and pulling the frame is just silly. You say 80 pounds of pressure, well how much of that are you loosing do to tire compression, as well as bearing spin. What you should have done is placed your foot on the splines, I think it would have come off much easier. My wheel does not freely come out of my frame and it has never caused any issued with bearings.
Kris is claiming this is completely a bearing issue. But how was miss assembling ruled out. I would still like to see a close up of the bearings… Also were the bearing holders bent in at all? (bent in the directions a clam shell would close)
I agree that the wheel would have spun well without the spacers, but there are two problems with removing the spacers:
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The ISIS spec requires a crank stop, which this system does not have without the spacers.
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The bearings are not press-fit to the axle, so without spacers they may not stay in place on the axle.
How do you think this might have been mis-assembled? Someone at unicycle.com using a hydraulic press to install the bearing caps? There was not unusual tension on the bearing holder bolts.
Here’s a picture of the bearings and spacers:
http://www.unicycle.com/shopping/shopexd.asp?id=1375
You can see that the width of the spacers is greater than the width of the inner bearing race.
The bearing getting stuck in the frame was not a result of sideways force; it was a result of deformation of the aluminum sleeve and galling between the sleeve and frame. The bearings themselves were not damaged (and as demonstrated, the wheel spun fine once it was out of the frame).
Well its obvious those spacers are to thick for those bearings. Clearly this is the biggest issue. Wouldnt have trying to use the setup spacerless, been the first thing to try. I do not see catastrophic failure in attempting this… neither does at least half of the ISIS riders out there. After riding the bearings might have broken in, showing less affect from the clamps… who knows.
Are the spacers also too wide side to side? Meaning are crank stops to big and the cranks push to hard causing the aluminum spacer to warp its way around the inner race of the bearing… are your spacers all deformed? Then you are right steel would be a better spacer/crankstop.
I think you are over thinking the whole do I or don’t I need a spacer/crankstop. Roger can not give you a straight answer because there is none, there are reasons they may be needed, and their are reasons they may cause problems. I have had both issues with spacers being too big, and being to small. I have had issues not using, and issues using them. The only setup I have ridden where it was needed to keep the bearing in place was a k1 hub as the bearings are on free moving shims. On my KH setup the spacers work as spacers not crank stops, they jingle around kinda loose. I have seen many of nimbus hubs spacerless… no problem.
Infact the only reason I use crankstops with K1 cranks (on a KH hub) is because without them I have no way to get the cranks off.
As I am understanding this is def not a hub design issue. It is a compatibility issue. The problem, in this case, is it is being sold as a complete off the shelf unicycle. I assume there was testing. So somewhere there is not enough quality control.
I am with Kris in wondering if simple grinding would have fixed this problem. In the 3-4 years of riding I have done with ISIS, I have made at least a half dozen spacers, as well as grinding down a couple sets.
This unicycle is for basketball, which puts a ton of twisting and sideways forces on the hub; I can’t imagine that a loosely fitting bearing would have any chance of staying put on the axle.
As noted above, UDC replaced my uni with one with 42mm OD bearings, which still has spacers, but of appropriate size for the bearing races. It works OK, although I’d still prefer press-fit bearings and no spacers.
I don’t think the spacer necessarily needs to be steel, but it’s clear to me that the bearing sleeve needs to be steel.
The inner bearing races are quite thin; I don’t think you could realistically grind down the spacers to work without failing, unless you have access to a real machine shop. Even so, no one should have to grind away at parts on a brand-new unicycle to get it to work properly.
Agreed.
Any further experience with the KH 22x40mm bearings?
Hello,
Just wanted to bump this thread back into the collective consciousness…
Has there been any further experience with the KH 22x40mm bearings? Has anyone used them without problems?
In theory it sounds like a good product as it would enable me to retrofit my Rick Hunter unicycle(s) with 40mm bearing holders to KH ISIS hubs.
But this thread is a bit disturbing. Additionally, as no one seems to have followed up here with any conclusive statements about this well intentioned product offered by KH.
Looking forward to your thoughts!
Cheers.
Yes, the problems are the minority, not the majority.
You need to be more gentle when fitting the bearings than you do with the normal ones. Although when they are set-up and working they work very well.
Roger