New KH 36er: possible loose hub?

Unicycles and Equipment
1

I would like to call on the collective wisdom of the Uni-community on this one:

I was so excited to finally get my new kh 36er today, and so after carefully putting it together, I took it out for a test ride, and almost immediately after mounting and within the first couple of revolutions, I felt a distinctive “knocking” sensation that appeared to be coming from the wheel. I checked to see if maybe the brake pads were rubbing, or maybe the assembly was loose, but that wasn’t the case.

I had initially checked the bearing caps during setup, and they were sufficiently snug; just enough so that the wheel would rotate freely without stopping to quickly. Then I double checked the cranks, and they were as tight as could be, with no apparent gap(s) in the spacers.

At this point I got back on and rode for a short distance, but the knocking persisted. I dismounted again and this time I grabbed the wheel and tried to see if there was any side to side play…and sure enough, there was! Not a great deal, but certainly enough to feel it while riding. The problem is, I assume, that if it is a loose hub, that it will likely continue to get looser, and even as it is now, the slightest torque applied to the cranks, causes the wheel to knock. It’s actually more of a jarring feeling than an actual noise, although I can hear it somewhat as well.

Now that I think about it, the rim is probably slapping against the brake pads with each revolution because of the torque on the cranks, but it doesn’t happen when you simply hold the uni and spin the wheel, since there’s no torque generated in that instance. And because the hub is apparently loose, it just makes the already inherent “flex” of the large wheel all the more pronounced.

Could it be that this new splined hub is faulty in some way, or maybe not fully pressed on to the splines? I don’t know what else I can do to eliminate the problem, but I think I’m right in assuming that there should be no “play” in the hub that would cause the wheel to move side to side. Any thoughts? Hopefully Kris will see this thread and maybe have the answer. :slight_smile:

2

I would go ahead and tell unicycle.com your problem directly, there’s obviously something off. I guess that means no new KH36 muni videos any time soon. : (

At first I thought it may have been the spokes settling in, which made me a little perplexed when I got my nightrider pro, but after a few rides, they settled in and stopped popping. it was the strangest sound, and I thought something was off.

3

Yeah I plan to talk with Josh at UDC, but I also wanted to post the question and my experience with it here, in case anyone else has had a similar situation and solved it. I’m hoping it’s just a simple fix or explanation that I may have overlooked. :o

4

take the hub off the frame, and see if you can find the source of the play. Try flexing the bearings a bit, and seeing if other things move/click. It sounds like the bearing caps are slightly ajar in some way.

corbin

5

My first guess was the bearing caps, but as I mentioned, I had gone through my normal process of adjusting them one at a time, until the wheel started to slow down fairly quickly, then backed it off in tiny increments until it rotated more freely.

One other interesting, but also troubling observation; I took the new KH 36er out on the very same beach bike path as usual, and it took noticeably more leg power to get up to, and maintain the same average speed. This was very surprising because the KH has 125mm cranks, and is considerably LIGHTER than my radial 36er, which also has SHORTER 114mm cranks!

It was mostly noticeable on the 15% grade ramp at the end of the ride, going back up to the parking lot! With my radial it’s almost effortless, even with the shorter cranks and heavier weight. With the KH, I had to do half revs just to maintain enough momentum to keep going! Seems stange for sure!

6

My 36 did the same thing. Well, it sounds the same. My bearing housings were tight, but I took them off anyway. Took them off, took the wheel out, then put it all back together and the problem went away.

7

Well, I think Corbin may be on to something! I removed the wheel from the frame, and checked the hub and bearings, but could not find anything loose or questionable. Then I placed the frame back on the wheel and instantly noticed that the bearing holders (on the frame), not the caps, were not seating fully onto the bearings!

I can easily “rock” the frame side to side, even while applying considerable downward force to the frame, but it just doesn’t seem to “seat” FULLY onto the bearings. This seems to be the problem, and even when the bearing caps are installed snugly, they still won’t force the bearings to fully seat into the holders, and the side to side movement remains. Can’t tell if it’s a width issue or a depth issue or both.

I’m thinking maybe it just has to break in, or I may need to removed the PAINT from the insides of the holders and caps so the frame will seat. That shouldn’t be necessary, but something’s amiss! :frowning:

8

I purchased my KH36 less than 3 weeks ago from UDC and felt the exact same thing on my first few rides, I was very confused and couldn’t figure out if it was just a “big ass wheel thing” or what. I assumed that the knocking was just the rim hitting the pads because there is so much flex with such a large wheel but I quickly noticed it went away after 50 miles or so. One semi major issue I’ve had with the UNI is several(2 or more) spokes would go “dead” per ride, so I preceded to tighten them to equal tension with the rest of the wheel. This problem was so consistent that I finally had my master wheel builder friend take a look at it and he equalized the tension and put a solid .5 - .75 turn on every spoke. The wheel is now very true and stiff, just like a bomber mountain bike wheel. I have been beating the crap out of this wheel for the last few days and the spokes are still perfectly equalized and the rim is still amazingly true, so my problem is solved.

I hope your issue is similar to mine and just goes away or only requires light sanding of the bearing housings like you mention.

9

Thanks for your input on the matter! I did just sand the insides of each bearing holder, and then tried seating a spare KH isis bearing (42mmx22mm) and it still would not go all the way in. When I pushed it in it would just pop back out, leaving a noticeable gap.

I thought that maybe if I put the frame back on and installed the bearing caps, it might seat this time. Well, the bearing cap screws went in easily on one side, and I tightened them as usual, but the other side! It took a great deal of force just to get the screws half way in! Yes, I made sure they were threaded in properly. The reason the screws were harder to put in was that the bearing was keeping the frame and bottom bearing holder from coming together fully.

That particular bearing holder was evidently not fitting the bearing as well as the other side, but I thought that if I cinched it down all the way that it would force the bearing to seat properly. The last 3-4 turns felt like I was over tightening the cap, but it wasn’t fully on yet.

It was just harder to tighten because it was also trying to force the bearing onto the frame and cap. The wheel still spins fairly well, but it does slow down too fast. This I’m sure is due to the excess pressure on the bearing, not from the screws being too tight, but because they are being forced into the frame, which just seems like it does NOT fit the bearings properly. But then, maybe it just needs to be ridden more and broken in as you mentioned. I sure hope that fixes it! :slight_smile:

10

I had the same thing happen with a new KH20. After tightening the bearing holders just enough so as to affect the wheel spin as little as possible I had the same symptoms you describe. Tightening the holders down a bit more took care of it but I have the same concerns you do and am hoping to be able to readjust the bearing holders after some break-in.

11

I didn’t get out the door with it, but on my new 29" (nimbus) my first assembly one bearing was not seated right. I forget what made me notice it but then I took them off dropped the wheel into place and everything just fell into place. Then I went through a ritual similar to yours to get the bearing caps on just right. I look for no ‘stop’ just a coasting to not spinning any more.

12

How long have you had your kh trials? How much have you ridden it so far?

Yeah I wonder if it will seat over time, or damage the bearing by having so much pressure on it until and if it seats itself and breaks in. My other concern is that, unlike chromoly frames, which can bend, the KH aluminum frame and bearing holders, with all this extra pressure on it from the bearings being forced into place, may cause the aluminum to crack! And doing any extreme riding, like any drops, might literally cause that to happen.

13

This doesn’t sound good. I think you should contact UDC and have them replace the frame since that seems to be the faulty part.
I wonder how a Schlumpf hub would take that extra pressure on the bearings :roll_eyes: :astonished: . The KH frames could definitely use some better quality checking IMO. If not done by the KH factory then at least UDC should check every frame they send out to their customers. I mean this could easily damage a Schlumpf hub, I guess.
First thing I thought was that maybe one of the bearings could be loose and sliding around but after reading more of your description that doesn’t seem to be the case.
Good luck with it all and have fun riding.

14

The bearings in my new KH29 frame are a VERY tight fit in the caps. The first time I rode it after putting it together (as tightly as I normally would with my Nimbus frame) it was very similar to what Terry describes - a knocking noise and the wheel moving sideways a lot as if it was very flexy. I greased the outside of the bearings a bit and did them up tighter than normal to seat them and it’s all fine now. I did wonder if it would be better if they didn’t paint the inside of the bearing holders, or machined it off after painting - they do seem to be rather tight. In fact, when I take the wheel off now the bearing caps stay on the bearings.

I think if I was fitting an expensive Schlumpf hub I’d probably scrape the paint off the inside of the bearing holders and caps first.

Rob

15

Terry: I had similar problems with an early KH36 frame that I purchased just after they were released. I also sanded the insides of the bearing holders to release some tension and this helped somewhat, but I also replaced the bearings, which I thought at time was the source of the play. The bearings on my 36 seemed really cheap and had too much free play in them. The replacements seemed marginally better.

The problem seemed to lessen with the new bearings, but I still feel like my 36er wheel has more side to side play than a wheel as tight as mine is and I still think there may be something off with the alignment of bearing holders on the frame or maybe heat distortion of the bearing holders when they were welded?

Have you checked all the spokes for even tension?? Most factory uni wheel builds seem a little on the loose side - and could use a tune-up.

Brycer

16

I purchased my KH 36 through my LBS about a year ago. My first time on it I felt a slight wobbly type feeling at the hub and cranks and could hear the noise that you described. All I did to compensate was re adjust / tighten the bearing caps that had not been snugged up fully and the noise and wobble went away.

I have the caps set with a 30 thousands gap between top and bottom (measured with a feeler guage)
At this setting the wheel drags ever so slightly however there has never been any overheating of the bearings.

I also had issues with at least one of the cap screws being quite hard to thread in.

17

Hey Terry,

The bearing housings on a KH frame should pop in quite tightly (e.g. you might have to hit the tire to pop the wheel out of the frame, on removal), but they should seat properly. First thing to check would be that extra powdercoating isn’t interfering with the machined fit. If that is not the problem then it is possible that the bearing housings were machined too small. Otherwise, 36’er wheels are particularly prone to needing spoke tightening after the first few rides on a factory built wheel - worth truing for sure (or taking to your lbs if you want). KH wheel are hand built, but still nothing replaces the care and attention that a good local wheelbuilder can give to a wheel when they only have to build 1 or 2 a day.

Kris

18

Thanks for all the replies everyone!

Thanks for the info Kris. After explaining my situation to Josh at UDC, he’s pretty sure it is a frame issue, and that at least one of the bearing housings were likely to have been machined a bit too small. I went ahead and brushed on paint stripper to completely remove all paint from the housings, and then after cleaning them out, I sprayed some dry lube, and they were then smooth as glass.

The bearings still fit tight, and had to be forcefully pushed into place, but they did seem to fit better. I the installed the caps and they tightened up fine, and I backed them off only slightly when the wheel started to drag under the compression of the caps. Again I tried moving the wheel to check for any play, and it still had free play side to side!

So one side of the frame seems to definitely not be seating properly, leaving the slightest gap between then frame housing and the bearing, resulting in the movement and knocking feeling while riding.

The good news is, that Josh told me he would be shipping me out another frame, and that he would test it on a wheel first, to make sure there are no seating issues. I made a short video showing the problem, and I will post it a little later, and I told Josh I’d send the link to him also.

19

It’s hard to have to wait for a new toy, but it sure is nice to deal with a company that is on top of whatever needs to be done. UDC is sure good about taking care of you. At least that’s my experience.

20

No doubt! I’m very impressed and quite happy with UDC. They have always responded to any questions and/or concerns in a very timely manner, and they stand behind their products 100%. They’re the best! :slight_smile: