Post your broken Uni parts here..

Broken flange of nimbus oracle hub at the spoke holes.

As you can see, I have a general corrosion thing going on.

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Got a surprise today! Loud banging started coming from the bearing during intense uphill training session. :smiley: Wheel kept turning fine and when took it off at home, I found this:

Got a pair of new bearings and changed the working one. I have a problem with the broken one though… Can’t pull from the bigger ring because the ring slips off and can’t get my bearing puller to hold onto the smaller ring. :angry:

Does someone happen to have a suggestion to easily remove the broken bearing?

Tough one! I guess I would start by pulling out every tool that I could imagine possibly using as a puller or a drift and seeing if I could get any purchase on it with any of them. If not, I would try to remove the balls and retainer and shields, then heat the inner ring with a torch until it started to show some color change and see if I could slide or pry it off then.

The absolute worst case is having to buy another hub and rebuild the wheel, which isn’t the end of the world. It’s a chance to upgrade to an ISIS hub if one was inclined, with the usual caveats about frame bearing holders.

Where it mine, I’d see if I could find a puller that might fit the inner race after the balls and outer race are pulled off. A cheap three arm puller may be able to do this.

If that didn’t work, I’d carefully take a grinding or cutting wheel to the inner race and see if I could split it. I’d use that much heat as a last resort, and only after un lacing the wheel.

Yes. I think it’s called Singapore! It’s hot and very humid there. :slight_smile:

Unhelpfully, I was looking at your picture thinking I don’t even have a suggestion to easily remove a perfectly intact bearing. I just got an old Miyata bearing off an old Miyata hub but my “fat” Craftsman 2-armed gear puller is too thick to even get behind the bearing without first working it off a bit. Then you have to protect the threaded end of the axle (it uses cotterless crank nuts). So I got a pipe cap that fit. But then I had to drill a hole in the middle of that, because the gear puller wouldn’t stay in place. Then I had to improvise a vice, since I don’t have a workbench… Basically, it helps to have the proper tools!

My thought also would be to try a dremel or a small grinder if you have it. Not much clearance around the flange, but if you can cut part of it, you might be able to then wedge something in there and break it the rest of the way or something.

I’ve never seen a bearing break like that. I wonder what caused it?

How about attaching a hose clamp around what is left of the outer bearing race. With the clamp tightened down tightly against the balls, you should then be able to use the bearing puller against what is left of the broken other race. Failing that, you’re going to have strip the bearing down so you are left with only the inner race, and pull that off on its own.

Thanks for advice everyone! Ended up “dremeling” the inner race and that helped to get it off:

I have no idea what caused the crack… Maybe some dirt had gotten between the bearing and it’s holder? :thinking: If this happens again, I will look more deeply into this. It’s only like 3€ for a pair of 6203 bearings though, so I won’t bother investigating this now.

Nicely done.

I had a bearing go on a ride. Unlike you, who are wiser, I had ignored bad sounds for a while. Then in the middle of some muni riding there was a sudden clunk, the wheel went loose and sideways, and a few bearing balls started rolling down the hill. Much better to take a look when it starts making noises!

Quick question. How long do bearings last on muni used about, 5 hrs a week. Months or years. Just got a big trip coming up. Might need to take spares… Thanks

Slightly curious about this too. My 36er bearings are feeling a tad squeaky, I’ve had them in there a good 3+ years with very little maintenance… :smiley:

I have never changed any bearings, although I don’t think i’ve done the same sort of distance as you. I did once ride my unicycle into the sea for a bit of a laugh, and bought some new bearings beforehand as I knew the outcome. Bearings were immediately crunchy and sometimes stopped turning, but I peeled the seals back and poured some engine oil in, and they’ve been working ever since… It’s been about 2 years. Never did get to use the bearings (although they came in handy for the final drive shaft in the gearbox of my honda C50 when that broke…)

This isn’t really broken, and i’ll continue to use it regardless, but are anyone elses cranks not at 180 degrees to one another? It’s a very old, probably cheap circus unicycle:

Bearing races are extremely hard and as such, they are also brittle. First, thin it using a grinder. Then place it on a hard anvil and hit it with a hammer and chisel to crack it.

Not broken, but certainly not usable

I think some Taiwanese sleeping beauty at the bearing housing welding department didn’t pay enough attention during the construction of my Impact frame. :roll_eyes:
That’s a bottom bearing holder welded to the left frame leg. So… with no thread on either side I guess I’ll just have to zip-tie the halves together… :smiley:

I guess I’m not taking my new Impact out for a 360 unispin this weekend… :frowning:

You could just make like a pressed steel bearing cup and use a nut 'n bolt :roll_eyes:

That’s a pretty weird defect though. I sort of assumed the part where they weld the bearing cups on is a completely seperate part of the process to putting the frame in the box with the bottom cups.

Most likely the mistake already happened at the station where they manufacture the cups. Because the parts are so alike they probably use the same machine for these parts. If they switch dies and they don’t completely clear the machine (or the cart/bin they collect they bearing cups in), things like these happen.

I am surprised nobody broke a part in 3 years (the thread may have been forgotten :wink: ).

Got a surprise 2 weeks ago when I found my muni crippled in the basement:

This pic was taken after I remove all the loose spokes (where the flanges broke) leaving 2 spokes on one side and 12 on the other (it is a 36 spokes hub/rim).

To be fair @MAD4ONE documents clearly that this hub is not meant for extreme use, should be built with Sapim Strong spokes in 4 cross pattern.
I had the wheel built by a pro but the Siamese wheels workshop forgot the 4 cross (or found it overkill?).

It lasted a good 4 years as I am far from being a muni grandmaster :stuck_out_tongue:

I was having some creaking noises for a while and thought it was a spoke tension issue. But the workshop guy checked and everything was good so he told me it might be spokes rubbing at the crossings (never was keen on greasing the spokes at the crossings as he suggested if I really wanted to get rid of the noise).

I am in the slow process of pulling the last spokes and realizing I am missing a few tools (some I never bought like bearings puller and some I have lost like a spoke wrench). But numbers seems to look encouraging for rebuilding with a KH hub I have and these spokes (that’s some silver lining). To be continued in the “lastest build” thread hopefully :crazy_face:

Is this with a 4-cross pattern rather than a 3-cross?
The flanges are clearly going to be larger on the KH hub.

That is where I am puzzled. I measured one of the spokes I removed to be around 251mm and the nipple was 14mm.
The UDC calculator gives about the same for a 3-cross on a KH hub !

Maybe I misread the lacing and the Mad4One was 4-cross. At this point, my concern is more about how much will this repair cost me and reusing the spokes is a significant saving.

To be continued when I will try lacing the wheel…


This makes me think again about buying a torque screwdriver. Not that the correct torque for things like this is very often specified.


I like those single bolt clamps with the steel barrel so you can really tighten them down without worrying about stripping the aluminum threads. I had never considered actually breaking the clamp itself! I’ll learn from your mistake :upside_down_face: