We would be making uni frames if we incorporate QR bearing caps… someday. but I have read a few threads, one recently, that if the cap isn’t tightened between 4-7 Nm on the knurled bearing -you’re on your butt. Tholub is right there! Steveyo is going to be the first to try the UCM bearing cap on his Schlumpf, and I’m sweating the clearances.
Oh yeah, see above 
Seriously?
I realize that the Schlumph is not as durable as a fixed hub, but is it really too fragile?
That comment, if true, makes me very concerned that a $1400 investment in a Schumph hub is a mistake.
Having already broken a $400 KH Ti hub and a replacement KH standard hub , both due to defective designs, all while doing normal XC riding (minimal drops and hopping), I can’t help but wonder if I’m throwng money down the drain if I buy a Schlumph.
It’s very frustrating to have only one choice in geared hubs and for that choice to be so sketchy.
Is there anyone reading this thread who would tell me to “NOT” buy this hub?
If so, please send me a PM, no need to muck up this thread.
It’s not due to rough riding - Kris and plenty of others have been riding hard and doing drops on these hubs for a few years now. They do have a sensitivity to having their special bearings over-tightened though. Like with other unicycles, but more so. You must only clamp the frame cups on tight enough to hold the knurled bearing without slipping, otherwise it is possible to ‘crush’ the special knurled bearing out of shape and it will start grinding badly.
Not hard to avoid, as long as you are aware of it.
Sam
So crushing the bearing(s) won’t damage the hub so much as require a new bearing? How much are new bearings and can they be replaced without returning the hub?
This would all be so much easier if the repair work could be done locally and if UDC was still carrying the hubs. I was told that UDC had so many warranty issues with the hubs that they didn’t want to deal with it any more…
Anyone have insider info on whether the hubs are going to be improved to address durability issues in the next year or so?
Someone may be able to give a more authoritative answer than this, but I think:
No, that knurled bearing is not replaceable without returning the hub. The knurled shell is attached to part of the hub’s insides, as it acts like the ‘torque arm’ in the original Schlumpf. The geared system needs three points of reference, and in the ‘KH’ hubs this is one of them. So damaging the knurled bearing-case (which in turn would damage the bearing inside it) requires some surgery of the hub, back at the factory.
It shouldn’t put you off buying one though; hundreds of people including me own and enjoy them (and treat them with a little care when installing).
Sam
Okay, that makes sense, but it begs the question of whether the previous design with the “arm” wasn’t better, just like BMX or some bicycle internally geared hubs.
I’ll keep thinking on this…
The advantage of the knurled bearing is that you can put it in any frame. But I personally prefer the old design, which was more reliable and less finicky.
Hey,
It’s true that there were issues in the first releases of this hub. The latest version is proving reliable. Personally, I’ve ridden a huge amount of terrain on my current hub in the past year and a half, including all kinds of wet and muddy conditions, and have had absolutely zero issues with it. Based on the frequency of warranties (barely any) on the newest model, that’s the case with others as well.
But it also has to be recognized that it’s a complicated part, that needs some taking care of compared to a single speed hub. Sort of like choosing to get a full suspension bike - you get performance with some accompanying responsibility for taking care of equipment. Although still not quite as much as a bike =)
Side note: if you don’t tighten the bearing housing enough and the knurled surface slips in the housing, check if the knurling has been clogged with powdercoat (scraped off the bearing housing). If that’s the case, scrape it out. A small hex key works well. That will ensure it still grips well. Personally I find this system a lot cleaner than any lever arm could be, and it works perfectly well as long as the bearing housing is clamped the correct amount. And importantly you can flip the wheelset either way, to let you choose your shifting direction.
Kris
Definitely my own fault. Uneven spoke tension built up over time + 15 gauge spokes?:
Check your spokes!
Ive been keeping mine a little looser and checking the wheel more often since im missing a spoke.
Any thoughts? Ive broken nipples and the ridden the wheel before fixing it, but theres no way i can fix this…
This happened to my last hub when i broke the axle. Schlumpf was generous enough to replace it. Will it be ok to keep riding so long as Im gentle on it and keep it true’d? Spending $150+ on shipping again is not appealing, even if he still honers the warranty.
Don’t be that guy ---->
= Broken Schlumpf!
Can you make a sharper picture? It could be that all spokes are inserted in the wrong direction - which can lead to such a failure. But I’m not 100% sure.
You can tell by the way the metal is broke which way it snapped. I will get a better picture up…
I know i laced the wheel right, but after wards realized the spokes were thiner then the 14 gauge i wanted. Rode it for about a month without re tensioning the spokes, One of the nipples broke and i replaced it, spokes were taught but, i still what i would call normal.
On the day befor i the flange broke, i noticed that several spokes had become substantially more tensioned than the rest but couldn’t find my spoke wrench. Major bummer when i saw what happed after that ride. Diden’t ride again until i loosened the spokes to a firm wiggle.
There is more flex in the rim now but i dont want to ruin another flange hole.
Same thing happened to me a couple weeks ago but with a smaller wheel and shortly after I installed the hub. Since that has happened I have been wondering if there could be a lower bearing holder cap permanently bonded to the knurled bearing which would basically eliminate the problem of getting the right tension to avoid slippage.
Obviously the bottom bearing cap would need to be suitable for a wide variety of frames. Any reason why there could not be a bearing cap bonded to the knurled bearing with bolt slots like the MountainUni UBM?
EDIT: KcTheAcy
I don’t think I would ride it missing a spoke like that. Not only would missing a spoke put uneven pressures on a rim but it would do the same to a hub. Not sure how much schlumpf would charge for a new flange/shell but I would get that fixed one way or another.
I’ve had the slipping bearing issue as well, which also resulted in a upd but a mild one since it was at low speed. I then suggested that either there could be two little notches on the knurled bearing opposite each other, that would extend between the halves of the bearing holder, or a single bigger notch that would point downward and fit into a matching lower bearing holder cup. Either way, slipping would be prevented. Kris Holm wrote (I’m quoting off the top of my head now) that they were aware of the issue but compatibility of the hub with frames in general was an overriding reason to keep the bearing just round. I don’t really understand that: what’s wrong with supplying a custom bearing cap with the hub? It would not hurt frame compatibility. Granted, it wouldn’t be compatible with a regular bearing holder - no big deal. Same with your idea.
This is a great idea! If the notch was in the knurled bearing and the corresponding protuberance was in the bearing holder cap, then the knurled bearing would be compatible with different bearing holder caps. All you would need to take advantage of this design would be one specialized bearing holder cap.
This is the sort of thing that a machinist and welder could do quite easily. Who wants to be the first to experiment?
Geoff
I now see I used the word notch incorrectly. Sorry, I meant protuberance. I’m not sure there is any room ‘in’ the knurled bearing housing to make a notch in it. But I wouldn’t weld anything on mine either: there’s an expensive bearing in there. So yeah, maybe a great idea, but not for DIY.
Oh come on, you go first. Just a wee little notch.
Sounds like a sure way to void the warranty! I only hope that when I get my G26, it will be 100% properly adjusted and ready to ride! And how does one know how to get the bearing cap at just the “right” tightness on the knurled bearing? Do you need a special torque wrench or other type of tool? I can just see it now; a 400 page manual, with poorly translated English, explaining all the maintenance requirements on the hub! :p;)
And the little shifter buttons! I’ve heard that these can fall out without warning, and need to be checked before every ride to make sure they are also properly tightened, or whatever you do to them to insure they will function properly and not fall out! Can’t wait for mine! 
)
Yes, you should get a low range (but not low quality) torque wrench for the bearing cap bolts. And if the range isn’t broad enough, another higher range torque wrench for the crank bolts. You’re already spending near 2k on the uni, what’s another hundred bucks?
If you tighten the little internal screws in the buttons, it shouldn’t be a problem.