Hi, today I went for a ride with my muni 26" when I started to hear a strange noise at each pedal spin, especially from the left.
It sounded like a spoke related issue but it was very regular.
At home I dismounted the cranks and the bearing half cage of the frame and made the wheel spin, hearing an even stranger noise, like if some metal small bits were in the bearing.
When I removed totally the wheel, I discovered that one of the bearings (the left one) was absolutely free to move by hand, I can remove it from the hub or put it in without any resistance.
The bearing is separated from the spokes by a kind of spacer that is also free to move and rotate on the hub.
Don’t know if it’s normal.
The baring is separated from the crank by another spacer, less large.
The weird sound was probably coming from a kind of very thin ring, less than one mm, that was probably a bit of the internal spacer, and when I removed it and assembled back the whole unicycle, everything seamed ok, although I didn’t try to ride, I just tried the unicycle on my room, half a crank spin forward, half a crank spin backward, everything sounds ok.
But the real question is: can I continue to use this hub like it is, or do I have to afford a brand new hub and mount a new wheel with the rim I already have?
the wheel comes from my 5yer old kahero muni, I only changed the frame (kh), the tyre (knard), the tube and the saddle (kh).
Sounds like the crank was loose. The bearing should be firmly held between the hub and the crank. Spacers are used if the crank does not come up against the bearing.
The spacers are normal between the flange and bearing, as well as the crank and the bearing. They will be able to move freely, and that doesn’t hurt anything, but if you can move them by hand when you have the cranks installed, that probably means your cranks aren’t on tight enough. (or you don’t have enough spacers)
It sounds like the inside diameter of the bearing doesn’t match the diameter of the hub “spindle”. bearings should fit very snug. having said that, if it doesn’t have any play, you may be OK.
Check the inner bearing surface (in the hole of the donut area) that comes in contact with the hub. Is it worn at all?
Pictures would be very helpful in diagnosing the problem. : )
My theory is that the bearing isn’t the 42x12mm (outside) designed to fit the KH frame, and there’s a spacer in there to compensate for a 40mm bearing? That doesn’t explain why the bearing wouldn’t fit.
… I know this is a long shot, but if you have a caliper, measure the spindle and make sure it’s 17mm if you’re running square tapered, or 22mm if you’re running ISIS.
In fact, the crank was well tight, maybe I wasn’t very clear.
It’s only when I removed the cranks from the wheel, and the wheel from the frame than I discovered that one of the two bearings was removable my hand without any resistance.
The bearing of the right side is normal, it is well fixed to the hub, if I want to change it, I have to use a strong bearing puller, and if I want to put it back, or to put a brand new bearing, I have to use a hammer and a bit of a seatpost.
But the bearing of the left side is not fixed to the hub any longer.
I can put it or remove it by hand.
Sure, if I put back the cranks, thanks to the two spacers around the left bearings, it will stay in place.
What I am asking here is : is it dangerous, or at least problematic to use on a unicycle a hub that has got one of the two bearings free to move (free to move when the wheel is not on the unicycle and without cranks) ?
Especially if it is a Muni
You just need to use Loctite Scelroulement “603” and to put a spacer between the crank and the bearing (as usual). I Did it on 2 unicycles without any further issue
Install a brand new bearing as after using Loctite glue, it’s almost impossible to change it after that
I wouldn’t call it dangerous. The worst you’re going to do is wear out the bearings faster, or do more damage to the hub than has already been done. Neither is a big concern if it’s already a “dead” part so to speak. If it doesn’t have play in the bearing when the crank is tightened down, I’d ride it til it dies and save up for a new hub in the meantime just in case.
I don’t know what you would use to do it, but you could try painting something on the hub spindle to make it thicker and fit the bearing properly.
The thin ring is not really a ring but circular (2 cm diameter) piece of metal (like if a metal wire was put around a cylinder and stay at this form)that is about 0.5mm large (in the two directions) and it seams that it was attached to the flange, cause when I look to the flange I see a missing bit of the paint that exactly fits this stuff.
The internal ring of the bearing seams round, and if I compare it to a brand new Qu-ax bearing I have in stock, Internal diameter and external diameter are the same. 42x12 and 22mm inside.
It means that it probably doesn’t come from the bearing but from the hub.
I guess the hub spindle has shrink a bit with time.
If the left crank stay well tight, I guess it’s ok, but in the case the crank gets loose, the left bearing will be only kept at it’s place by the frame, and I’m rather worried about this scenario.
I remember that the Koxx ISIS Light hub and the KH/Onza splined hub had bearings that you can move by hand. They both were pressing on a small shouldering that prevented them from stressing the flange by sliding inward.
Even if it is usually a tight fit, it should be okay to run it this way if you make sure:
the inner spacer is not moving at all (glue it to protect the flange)
the bearing do not have a sideway play (it can slide on the splindle but should not be able to lean on the side)
Of course, you already have a proper outside spacer that keeps the bearing in place when riding (preventing any slide). If you are worried, put some nail polish on your crank’s bolt and it will stay tight
Well, I will glue the inner spacer as well as the bearing.
I still don’t know what is the round bit of metal that I found.
Here is the pic of this stuff close to the bearing that I will replace by a new one (but this bearing seams ok though)
I have found a similar stuff few days ago on my room, probably after having changed some cranks, exactly the same stuff indeed but with a bigger diameter.
It could come from another unicycle as well, I use to change cranks on my 4 unicycles
If it was mine it’d be worth it to get a new set of bearings and see if a new one is still loose.
If it is, I’d be replacing the hub.
But that’s me and ymmv.
My thought is that it should need to be pressed on, so we there it works now or not, it’s not right. Right’s right, and wrong’s wrong, and wrong will never be right. Right?
In fact I have already tried that and the new one slides as easily as the old one on the spindle.
Even if the old one seams ok, I will put the new one, I will glue both the internal spacer and the bearing, only the external spacer won’t be glued.
I’m not wrong if I say you are right. Right?
It’s not in my plan to buy a new hub and a set of spokes for now.
I have already spent about 300€ (kh frame + surly Knard + tube + kh seat post clamp + brake lever mount - and I’m not counting the HS33 that I was planing to mount on my 29er, and the kh fusion street that I took from my 19er) to transform my old muni to this new toy.
If I can fix the bearing for the price of a special glue, it’s definitely worth it.
A couple of years ago my 36" Coker started making grinding noises on a ride, and eventually my cranks locked and I UPD’d hard. I found that both bearings had been slipping on the spindle and the fork was spreading wide enough for the frame bearing housing to grind into my cranks (carving a wicked trench) and eventually locked up the cranks. Since this is a cotterless spindle with no spacers, I ended up doing the following:
The bearings were slipping easily on and off the spindle where it should have been a firm fit. I contacted some pros, and they said it should be a firm fit for that spindle. I manually knurled the spindle where the bearings sit, using a hammer and a spare screwdriver. Not the best method and tough to control. Also applied locktite and installed new bearings.
As a safety/peace of mind measure, I cut up a spare bicycle handlebar end cap and slipped that over the spindle as a space between the bearing and the crank. I couldn’t find any official spacers made for this.
These measures seem to have made the Coker ridable, however I’ve had the bearings slip a little and the fork spread out again, but I get a warning squeak sound with the rubber ‘spacer’ in place and the cranks don’t touch the frame anymore. I’ve been told the only concern with this is water getting trapped in or around the spacer, but I have not seen a problem with this yet.
If you are using spacers and everything is snugged up a loose fitting bearing should be a non-issue. Gluing should only be necessary with square taper or other systems that do not use a spacer between bearing and crank.
Have you tested your wheel after since you put it back together? If the problem is solved there is no need to break out the loctite and new bearings.
Could you describe the noise a bit better? If the noise continues with the wheel re-installed I would look at your pedals, or possibly the hub if it is built with a keyway or pressed on flanges.
That bearing was designed to be held on by press fit, not glue.
Is it really an issue? Probably not. But is it right? No. If you need the well then yeah, I’d have no problem riding it while I hunt down a new hub and spokes.
But like I said, that’s just me. I don’t care what you do.
I didn’t test the wheel once I put it back since I was exhausted and my left knee needs some recovering days (juggling with two different knee pains in the left one).
What I’m sure is that the noise didn’t come from my left knee
The noise was something like a worn car suspension cracking when passing over a speed bump, or … i dunno… let’s say a loud person siting hard on a very old bed.
At the beginning it was like a spoke noise, but it was happening in a regular basis after few km, cracking the way I just described.
I already ordered the loctite and had a new bearing under hand so as soon as I receive the glue, I will glue it since I don’t want my frame to do the splits
The hub is from my very first unicycle, it was a french brand http://www.kahero.com/ that builds cheap unicycles.
I don’t know if they build the hub, the muni I bought is not in the market anymore.
There is a good chance that the hub reference was : Kahero Centaur Black ISIS Alloy Cr-Mo
I bought it about 5-6 years ago.
The crank was still tight before I disassemble it.
I also suspected the pedals since I rode this uni twice few days before it happen and there was no noise, the only thing I changed for my last ride was the pedals, and if I remember well, I had a pair of pedals that was doing some strange noises or with a strange feeling in the feet few months ago.
It’s possible that I put those pedals in the muni for this last ride.
Their also was this round piece of metal that I extracted from the hub, which is on the photo I posted.
This was making an grinding noise when I was making the wheel spin once the uni upside down, and this noise disappeared when I put it out.
But this was a different noise from when I was pedaling.
During the ride, I tried to localize the noise by reversing the unicycle and making the wheel spin, but didn’t hear anything, and as soon as I was pedaling, more precisely when I was pushing the left pedal, the sound was here.
Still waiting for the loctite 603, but I got the muni assembled to day to give it a try on my parking and didn’t hear any weird noise at all.
I changed the pedals though.
The muni seams to be ok, it rolls and hop without any issues, even without gluing the bearing but I will glue it anyway as soon as I have the loctite.
