Major Hub Flange FAIL!

After jumping a 6 set yesterday, I thought I’d bent my rim, even though it’s stayed true for all this time doing bigger stuff than that. So my LBS got it spinning perfectly true and so today I decided to try it on a smallish, 48" drop off of a loading doc. (It was in back of the place where I just had bought my new ipod touch! Yay! The built in speaker was the deciding factor for me)

Anyway, I did the drop, and immediately upon landing it I heard a loud THUD, and the wheel, once again, got pushed to one side, locking the brake and throwing me off! I thought, wtf! Then I looked and noticed that the right side flange had collapsed and broken! Well, after 2+ years of heavy use it finally gave out, so I can’t be too surprised.

But it is apparently the one weak spot on the '07. The hub flange was drilled-apparently to save weight. And that’s exactly where it broke, in the weakest area where there is the least material. But it just really made it all the weaker. So now I gotta get a new HUB asap so I can get back out there and ride!!!:slight_smile:

**PS: If anyone has an extra decent isis 36 hole hub that will fit (not the '07 though, lol) and live somewhere in LA/OC, PM me and I will buy it from you!)

Click here: Hub Breakage time!


Wha! You should get the new 09 hub. It’s the first time I see a hub like that, but I knew it could do something like that because of the force on the wheel. The tire/rim is going forward and the hub/cranks are trying to go backwards to brake, so that’s why it broke. I feel like a scientist :slight_smile:

Yep, the '07’s were like that and very weak because a lot of material was cut out to try to save weight. I am ordering a new '09 tomorrow, and those look super strong with NO cut out material!

Here’s a few more pics since I took it all apart for relacing to the new hub. There were/are stress fractures at EVERY single weak point (nearest the axle) on BOTH flanges, and probably have been there for a while, and getting worse all the time until today, when it finally went bye-bye, to that big Hub-heaven in the sky! :stuck_out_tongue:






i don’t think they have holes to save weight, but to make it easy to take off, put on and replace spokes.

Hmm, I’m not sure about that. Look at the '09 hub. The flange is solid, as it should be, and also flares outward towards the hub for more strength. And any LBS should have np removing/installing spokes on this or any flange. :slight_smile:

09 hub.jpg

I think it broke because it was so dirty!

Just kidding.

Haha, you may not be too far off! There could very well have been some corrosion going on since it has been exposed to pretty harsh elements-both wet & dry-in the last couple of years. I think that once the PC surface is compromised by small stress fractures, it becomes more susceptible to outside contaminants, rust and corrosion. With all it’s been through, I’m actually happy it lasted as long as it did! I sure got my $$$ worth! :o

I haven’t seen that type of failure before

I am inclined to agree with this, or at least, I can’t understand the purpose of these cutouts for weight saving. The stupid nubs are sticking out doing nothing. If these holes were made to save weight, they would be round or oval, not leaving heavy stupid loops of metal that support nothing. I mean stupid as in being heavy while doing nothing, why are they there?

I hadn’t looked at UDC’s hubs lately, until I read this thread. I think KH didn’t want to read any more about KH flange bending ! KH is an amazing company, very fast to respond and change.

I hope some of that rubs off on Florian and we get geared hubs that fit into a “socket hub” , allowing the gearbox to be removed fast without unlacing the wheel. :sunglasses:

Those cutouts are to save weight. They have “heavy stupid loops” because he wanted the cutout to say “KH”. I’ve delaced and relaced a Nimbus hub, and I never once thought, “man, I wish I had some KH-shaped cutouts here to help me!”. There’s just no way it could assist with spoke maintenance.

Yeah, always thought that was a very poor design, just like the new touring handles :frowning: . (Btw, how are the new adjustable seatposts holding up?? The 09 hubs look really nice, hopefully the flanges are strong and they stay engaged to the spindle. I decided to go with the nimbus hub for my wheel.

And the $460 KH titanium hub has the SAME cutouts as my '07! I also thought of getting the nimbus hub, but it also has cutouts, although they are round and probably won’t weaken it. I am also wondering about the '09 KH hub now that they did away with the traditional welds, and went with a splined version. We’ll see! :o

I think we are right about round holes for weight savings

Just look at the new designs.

Terry is being very classy, in letting us see the failure, while insisting it was due to heavy use over 2 years. I don’t think Terry will ask for a new hub, but perhaps KH will send him one anyway after seeing this thread.

KH is the most amazing uni maker ever, and this is the only part of a KH that I can point my finger at and say WTF ? I am proved right by the new KH having the round holes.

That said, I totally agree with Terry that it failed because a hard core jump slammer like Terry beat on it for 2 years. I don’t care if KH gives him a new hub or not, and neither does Terry, but KH might give him a new hub anyway because KH is a rare company, that when it makes rare mistakes, will swap out parts, even if there is no warranty.:slight_smile:

The new KH has “round holes”? The only round holes in the otherwise solid hub flange are solely for the spokes, unless you meant something else. And thanks for your kind words. :slight_smile:

You can join my team: Team Never Wash Your Muni.

I didn’t notice that detail

It is the Nimbus with the round holed hub.

Sad that the uber cool Ti hubs are saddled with the mark of stupidity. I am only an amateur engineer, and I have enough uni experience to know that the Ti hub wouldn’t make me a better rider, until I get skilled enough to whip the uni around. But who cares ?, I still want a Ti hub. But now it’s theoretical perfection has a blemish. I can’t buy an irrational piece of theoretical advantage that costs so much if it has an engineering blemish LOL.

I’m not trying to be a vulture after road kill; however, I’m looking for a broken uni hub for a project I thought of a while back. I don’t know what you have planned for the hub, but I’d be happy to pay shipping to colorado to take it off your hands.

Pm me if you want to unload the dead weight.


Hello Jerry. I’m actually going to keep it as a memento, and have a little glass case made for it, as a kind of document to the fateful event! The inscription will be something like:
“Kris Holm 2007 Mountain Unicycle Hub, broken during a stair jump on 6/26/09. Rider: Terry “UniGeezer” Peterson, aged 53.”

:):D:o :sunglasses: :stuck_out_tongue:

haha that would be sooo cool. gutted about your hub but now you get a brand spanking new one

Oh! I can join that team! I haven’t washed mine yet, and I don’t plan to! Have you ever considered making a group on the forums for that?

Back on topic, the new KH hubs look much better with their tapered flanges. They are completely CNC’d so there are no welds. The glass case idea sounds pretty cool, too. :sunglasses:

This is why I hate changing spokes out on my trials uni. The flanges bend in towards the center of the axle. taking a spoke out I dont mind bending it and tweaking it around so that it gets out.

But trying to put a new on in sucks. Because of the angle of the bent flange it goes straight into the other flange. I have to bend it to make it fit, which just ruins a new spoke. So to put new spokes on, I have to bend the flanges back to being straight. Then after riding they bend back in. A new wheel build means pulling the flanges apart again.

Every take a paperclip or pop can and just bend it back and forth until it just comes apart, smooth as butter? Yeah, same concept. Soon my hub will just come apart.

Horrible design.