Oracle 36 hub still squeaking ?

Just got a oracle last week with the nimbus impulse hub, Steel isis with aluminium body i have read about them squeaking many years ago so i though the problem was over now :thinking: I got 30 Km quietly and now its noisy, is there a permanent fix to that ? other than trashing a brand new hub. Its got to be from there i have put some grease where every spoke crosses, removed the wheel from the frame with only the cranks / spacers and no pedal, holding the wheel down and pushing on the crank reveals play, not a big amount but enough to make noise. By putting more grease on the crank, both sides of the washers and screwing the isis bolt verry tight i still get a tiny bit of movement sometime but the noise is gone, i suspect the washer against the other parts was doing the noise.

I will see how long it last :o

Have you checked or considered reducing the thickness of the spacer washer? If the spacer washer is too thick the ISIS crank will not seat correctly on the axle.

This is a pretty good past discussion in the spacer washers:

Update: JimT just mentioned the spacer may be too wide. I’ve had a motion problem when the spacer was not wide enough…read below, please.

Part of the ISIS specification, if I understand correctly, is a ‘stop’. That means the crank stops as it is forced against the spacer. If your cranks are tight but there’s still a gap between the crank and spacer, then maybe you need wider spacers. The ‘play’ you are describing may be a result of an imperfect match between the splines of the hub and the inside of the crank. Check to see if the ‘stop’ truly exists. That might stop the motion.

Without a spacer, the cranks can bottom out against something other than the spacer, producing a kind of inadequate ‘stop’ which is prone to movement.

I did not know that spacers even existed on my first ISIS unicycle…until months after one of them fell off. While it was off, I kept the crank bolt tight, but there was still ‘play’ in the crank. Not very smart on my part. But I fixed the problem, and now things are good.

I will check tonight it could be crank and spacers issue. Hopefully ! My cranks came loose while riding despite being very tight. It’s the stock washers between the bearing and the crank not sure about the tickness.

My post (from april26?) on the thread you started about buying a 36 may still be relevant even tho you notice ‘play’ in the setup. Mine felt the same but it’s not so much ‘play’ as a kind of creak or ping or knock that feels like play b/c of the vibration that travels up the crank arm when you get the bearing to pop at the surface of the isis axle. In my case and as I described, it was the interface of the hub bearing and the isis axle catching and letting go a super tiny distance but very noticeable nevertheless in the vibrations it produced. Initially I tried everything else like you did and at first I thought I’d solved the problem w/ a lot of grease on the spacers/crank/splines/pedal threads/etc. b/c the creak went away. But it came back in 25km or so. That’s when I decided to pull the bearing as a last resort and presto! problem solved. So I still recommend trying that.

I know it’s a PITA to pull the bearings if you don’t have a bearing puller but it’s so worth not being aggravated by the noise and it will come back eventually anyway because moisture gets in there somehow and drys out the surface leading to more creaking so the investment in a bearing puller will pay off eventually. I resigned to periodically pulling the bearings and regreasing them when they start complaining again which they seem to do about every 6mo or so. I think riding in the wet speeds up the process leading to creaking b/c water somehow wicks into the interface btwn bearing and axle.

I’m not 100% certain about the above but it’s my best explanation for what I’ve observed w/ my Stealth (and 4 other unis) and so far so good… Best luck w/ your setup, you’ll track down the problem eventually. There are only so many things that can creak and you can check them all eventually. But if you aren’t checking the bearings you can’t eliminate that possibility. Press fit parts are notorious for creaking. At lease in our case we can re-press them ourselves w/ a bearing puller or the skilled use of a blunt punch.

Good luck and have fun on your jumbo uni! They really are fun and a pretty different experience from any smaller wheel size. Makes me wonder about a uni made from a penny farthing wheel. Mounting the thing would certainly be different!

I remember reading your post about putting grease under the bearings but I don’t have a bearing puller I trues to rig something quick without success. Does a regular 3 jaw gear puller works ?

That doesn’t sound right. I wonder if your hub is slightly undersized for your bearings?

My Nimbus 36er (older design with a non-disc steel hub) has zero play or noise and has been ridden hard for two years in a range of temperatures with plenty of inclement weather thrown in. Chronic creaking sounds like something is wrong to me.

You could take your uni to a bike shop and they can remove the bearings for you. That’s the first way I did it before buying the Nimbus bearing tool. I vastly prefer doing my own work on stuff so I bought the tool and it was worth it. Now I just need a truing stand and my shop will be complete.

I wouldn’t want to try to punch out the bearing myself b/c I’d probable end up punching out the bearing seal by accident but that’s how I think the bike shop does it so it’s just a matter of skill. But the bearing puller is super easy and works like a crank puller does essentially. You screw the bearings off… Buy Nimbus Unicycle Bearing Puller Online If you get everything stripped down the bike shop should be able to pop the bearings off for pretty cheap I would assume.

I would agree to this. The design of a working bearing in our case is as follows: Outer bearing ring shall be fixed in the frame, inner one fixed on the axle. Then the bearing runs on its inner balls as it is meant to be. If grease is applied between axle and inner ring, friction is drastically reduced. If the bearing dies the inner ring can run into the axle.

If there is play between inner bearing ring and axle, there is something wrong, but grease is not the fix. If, at all, the inner ring should be glued to the axle (e.g. Loctide has products for shaft hub connections).

Congratulations, you’re one of the lucky ones! Maybe yours has better grease than mine did. I’m not 100% certain of anything and certainly not my advice on pulling the bearings but it worked for me and the creaking hasn’t come back on my Stealth so I assume that must have been the issue. It was only one side and I only fixed that side but fixed it was after I regreased the surfaces. The bit on every 6mo is based on a very limited sample size so that’s the part that I’m least confident on and I hope I’m wrong on having to redo the job that often. And my KH unis haven’t creaked much yet, just a little, so QC and precision tolerances may be an issue w/ the Nimbus brand…

I hope I don’t come across as dogmatic about this, that’s not my intent. I’m just sharing my experience.

I think my Stealth essentially has zero play as well but I’m inferring that the steel stretches or moves a bit at the inner race of the bearing when you put crank leverage on it leading to the creak if the surfaces aren’t sufficiently lubed. The same thing happens with press fit bicycle bottom brackets, press fit headsets, press fit fork crowns, etc. The guys at the bike shop said they regularly pull their bottom brackets to regrease the contact surfaces because creak comes back periodically. I kind of assumed I would too. Time will tell.

I think the person who built my Stealth just didn’t apply enough grease on one of the bearings and that’s what led to the ugly creaking noises. I used Slick Honey on both the axle and the inner bearing race and so far so good. Maybe the fix will stick? Hope so.

I’ve been having the same creaking issue in my Stealth since I got it. My buddy is convinced the creaking sounds is coming from the spokes, and it sure does sound like it. There’s not many other possible sources on the uni. Pedals and cracks are super tight. I’m planning to install a disc brake soon, when I do I’ll grease the contact points around the bearings. Should be done in a few days, I’ll report back afterwards.

I take your point, but note that press fits are used in all sorts of applications with greater stresses than a unicycle.

Something to consider: when you regrease your bearing/hub interface you also remove and reseat a) your cranks and b) the bearings in the frame. Are you 100% sure the noise isn’t coming from one of those places?

JimT and elpuebloUNIdo you both are right!!

I torked my crank bolts like hell and went riding again, my right foot is definately rocking back and forth a tiny bit. I disassembled the crank at home and im not too happy about the results. Disc side : Crank held in place against the spacer = no rocking. Right side : Crank held in place against the spacer, its rocking a lot, seems like it needs to go further in about 2.5mm according to my digital caliper.

The bad news is ; Measuring from the axle end to the bearing inned race on the disc side i get 22.8MM , Measuring from the axle end to the bearing inned race on the right side i get 19.23MM.

Is that normal to have the hub sides sticking out 3.5MM further on one side ?

Both my spacers are 7MM, putting the right crank on without a spacer to the point it stops rocking, i would need a spacer about 4.5MM, The Disc side seems ok

Sounds like you may have found your problem. When using aluminum cranks the ISIS standard says that there should be about 3 to 6mm of space between the crank and spacer washer when the crank is pushed on by hand. If the space is smaller, then you need a thinner spacer washer.

I just measured the axle I took off my new Nimbus Stealth. First, as it came new there were different thicknesses of spacer washers, 2mm on the right and 2.5mm on the left. I also measured the distance from the end of the axle to the bearing as you did. On the right is was 20.68mm and on the left it was 19.89mm. I also noted that the thicker washer was installed on the left side, that is the opposite as one would think. So I think rather then the distance from the end of the axle to the bearing as an indication of how thick the spacer washer should be it would be best to go to the standard recommendation above.

A ISIS spec can be found at:
Note section 3.1.2 and 3.1.3


Sounds like you may have found your problem. When using aluminum cranks the ISIS standard says that there should be about 3 to 6mm of space between the crank and spacer washer when the crank is pushed on by hand. If the space is smaller, then you need a thinner spacer.

I don’t understand that 3 to 6 mm thing. Is that spacer washer the one on the crank m12 bolt or the axle washer on the hub ? Because just pushing the crank arm snug with my hands the inside of the crank got only 1mm shoulder for the bolt washer to push on so I think I couldn’t go snug by hand then 3 to 6 mm more in

This 3-6 mm is the rule of thump for distance between crank and axle washer. That applies for installing new cranks. Once you mount aluminium cranks on the steel axle they obviously widen up a bit. So on reinstallation they will come much closer to the spacer. That is one of the backsides of ISIS. Frequent installation (of the same cranks) will widen them out.

I realize that Pierluc’s problem is probably w/ he arrangement of his spacers so the following rant is probably not pertinent to his issue. But I don’t want to waste this rant :wink:

Yeah, call me crazy but I tried all the easy fixes first. I have greased those surfaces a crap ton w/o lasting success. I’m all about inference to the best explanation–abduction. I gave you the best explanation that I’ve come up with. I’ve been f’ing with my unis for 3 years trying to track down creaks. What I’ve described is my best take on them. Creaks can come from all over the place but when you’ve addressed all but one source the reasonable thing to do is try that one last thing out. Of course, it’s the least convenient so ppl might resist doing it. Like I did until I gave in to my natural curiosity.

I’ve had cranks/pedals on and off multiple times b/c, I agree with you that it’s the best first explanation. But it failed the empirical test. Conclusions derived from the armchair are for philosophers who don’t need to live in the real world. I prefer empiricism to rationalism. Go ask a bike mech about press fits. They have to work with them a lot. They’ve got the empirical data. Press fits creak and press fit radial contact bearings are a shitty design for that and other reasons

I’m sorry for getting cranky about this. I shouldn’t care if ppl doubt me. They can repeat all of my efforts themselves. I’m just suggesting something that worked for me. I’m not guaranteeing anything. But it might save someone a lot of aggro. I would have appreciated my suggestions 2 years ago when I started this journey.

I took my Stealth apart today and fixed my creaking issue! Super easy!
It seems like the creaking issue was coming from the bearings, specifically the bearing housing. I used a small amount of friction tape on the bearing/housing contact points. Boom! Silence! I took her for a 5 mile test ride and I didn’t hear a single peep!

I took a couple pics of the process:

1 Like

Apologies, I didn’t mean to ruffly any feathers. If you and I are ever in the same part of the world at the same time let’s go for a ride :).

I got some work done on the bearing spacers tonight!
Sanded the left side side one from 7cm to 6.4cm and the right side one from 7cm to 4.2cm!
when i push the cranks in tight by hand, i get a small 1 millimeter gap that gets pressed close when i insert the bolts.

This seems like the right fix! been pushing hard on those crank and cant get any movement like before.

No actual riding done yet! i might try to go for a big ride soon and report if it works

Thx for all the tips!