Last week I thought GUni’s were great. Today I think they suck. Maybe next week I’ll give you a balanced opinion.
Now I have no idea how much 50Nm is. That’s what was scribbled on the Schlumpf manual. I have no idea who wrote it in there. It’s either Florian or the UDC boys.
I tried Spencers double nut technique today. The shaft takes 5mm nuts. Unfortunately it didn’t work.
The next option is to take it to the bike shop on Monday to take my crank off (I brought the wrong crank extractor with me- non-ISIS). Hopefully that will give a bit more leveraget to work with.
If that doesn’t work, I think I’ll break the button so that the dome is off. I won’t be able to shift whilst riding, but at least I can get in there and tighten the loose crank, which is what is stopping me riding at the moment.
The unit of torque Nm is the product of force expressed in Newton and the length (between the pivot point and where the force is exerted) expressed in metres. 50 Newton is about the weight of a mass of 5 kilograms. So that force exerted on an arm of 1 m is 50 Nm. If you grip your allen key 10 cm from where it turns (which is quite much for a 2.5 mm size key), you would have to pull the 10-fold of that, i.e. 50 kg. I guess that’s almost your own weight (Ken). If your allen key is shorter, you have to pull with an even bigger force to get at 50 Nm. Go figure: 50 Nm is a lot of torque for such a tiny screw!
But I thought the issue with accessing the crank screw was that the button is in the way, not the type of extractor?
Edit: careful with breaking the button off its stem on purpose. Don’t damage the shifter shaft or you’re worse off.
Ken, I just read the KH-Schlumpf hub manual, and nowhere in it does it state that the 2.5mm allen grub screw should be tightened to 50Nm! Florian told me when he gave me the hub that the crank bolts should be tightened very tight, and in fact 50Nm was the torque he recommended. Maybe this is what you’re getting confused with.
I feel your pain - I spent hours and hours trying to fix the side to side play inherent in my road Schlumpf hub to no avail. It just about drove me nuts!
Oh yes, Florian sells pre-calibrated torque screwdrivers as an accessory. From personal experience I can highly recommend these to owners of the Schlumpf road hub. They make tightening up the 1.5mm grub screw to the required torque so that the buttons don’t fall off oh so easy. I don’t know if they are so essential for the newer KH-Schlumpf though, as I’ve never had to mount the buttons of this hub.
Oh ok, I read it in the manual but never took any notice of it, because I don’t have a torque wrench anyway. It could say 1000Nm for all the difference it makes.
Have you tightened your torque lever? I had some play with the road hub and it went once I tigheted the torque lever. Also, your frame does flex a bit…you could try sticking a brake booster on there to stiffen things up.
What didn’t work about it? Were you able to get a solid grip on the two nuts to tighten them against each other? Once they’re tight, you should be able to use a socket to hold the shaft.
How did you damage the thread? Were you trying to grip it with pliers or something?
Also, as has been pointed out, 50Nm is the torque needed for the crank bolts. This equates to pushing really really hard on a socket T-bar (not a ratchet - you’ll destroy it) and giving it as much welly as you can. The manual for the new KH hub doesn’t specify the torque needed for the grub screw, but the original road hub needed 1.1Nm - or about finger tight plus 1/4 turn for good measure.
I’ve got a brake booster on my Maguras already. The play that I’m talking about feels like the bearings are loose on the axle. Even with the optimum number of spacers on the axle (as adjusted by Florian Schlumpf himself) there is still some play. Tightening the torque arm won’t fix it. However it doesn’t seem to matter too much and it isn’t noticable (or distinguishable from the crank slop) when riding. I tried the same hold-the-frame-steady-and-wiggle-side-to-side test on a couple of other road schlumpf hubs at UNICON and they all had some side to side play. My conclusion is that this play cannot be eliminated and originates from the lack of lateral stiffness of the bearings themselves.
On the subject of 50 Nm torque for tightening the crank bolts:
I believe your manual had the figure hand written in by Florian (it wasn’t us folk at UDC). I took my hub in to a bike shop to get the cranks tightened and they looked at me like I was crazy when I requested a 50Nm torque on each crank. It turns out that when dealing with bikes the highest they use is generally 20-25Nm. We managed to get one crank to 50Nm but it was a behemoth of an effort and the other one was harder to tighten and only got to 30Nm.
The interesting thing was that despite them being on ridiculously tightly they still need tightening up after the first few rides. I didn’t bother taking the uni back to the bike shop but I did tighten them as hard as I possibly could without a torque wrench. For good measure I repeated the process after a few more rides.
I would recommend all new KH/Schlumpf owners to check your crank tightness fairly regularly, at least for the first wee while.
On the original (with torque arm) ones, the black hubs were supposed to be a bit better in this respect - as the black coating appeared to make the bearing tolerances slightly tighter. That’s what I was told anyway, and why I got the black one.
Ken - you must know someone with a drill. It’s a quick job to drill off a button. If you do it carefully, it doesn’t destroy the button, and all you need is an easy to get in the hardware shop grub screw/set screw. If it does destroy the button, then yeah it’ll be a bit more hassle, but better to do that than to destroy your shifting shaft.
For that matter, you’re in a hospital - can’t you find a surgeon with an expensive drill and a very steady hand!
For people tightening the buttons to the right amount - the key thing I’ve found is first to put the buttons on and get them adjusted right, then to use two allen keys, and tighten them against each other, with one allen key in each button. That way you seem to be able to get a much more consistent force onto it.
Hurrah! I got it unstuck today, using Spencers double nut technique. I had to go to the bike shop first to borrow their ISIS crank puller. Once I got the crank off I was able to tighten the two nuts against each other, and then unscrew the stuck button on the other side.
The surprising thing is how easy it was. I hadn’t actually tightened it all that hard. I think the trick is to only do the buttons up finger tight. And NEVER tighten them against each other with the Schlumpf two pronged tool on both sides. I think that’s why it got stuck. I happen to have two tools because I have two Schlumpfs.
I just tried shifting it manually and if you don’t push the shifter in far enough you get to some deadzone where the thing will freewheel constantly without engagement. Is something broken in my hub? If I push the button all the way in, it engages and that’s not a problem, but if it’s stuck in the half-shift zone it just spins away like a freewheel
You mean do the little screws only finger tight? Because the buttons you don’t tighten at all, you adjust their position to make them flush with the crank when pushed in. They’re not tight because you could screw them in further. This adjustability is needed because you never know exactly how far a crank ends up the taper (square or ISI) when tightened.
You should indeed never do that, but your statements makes me think you’re appraoching it the wrong way. You shouldn’t tighten the buttons at all. They’re somewhere ‘halfway’ the thread. Fixing them there is done with the little screws. Read your Schlumpf instructions on how to position and tighten your buttons.
Cool. How many people can say that apart from Schlumpf himself? Does anyone know?
It may have to do with how you adjusted (or NOT adjusted) the buttons, in that the shifter shaft can hardly go in far enough to engage the other gear because the button holds it back. There should be some play when pushed in, i.e. you must be able to push it somewhat further. It is important to get this right. My Schlumpf instructions bolden that part.
I hadn’t realised that I had just expected you to have removed the other crank, so probably didn’t make it clear that you needed to do that to get to the thread .
Glad it worked out. And as Klass says, check the instructions for button adjustment. Mainly by luck, mine seem to be really well positioned so they’re easy to shift (when I want them to), and never shift by accident, and it’s almost impossible to get to the half-shifted-freewheel stage.
As Klaas Bil notes, if you tighten the button too much on the shaft, it won’t be able to push all the way and the hub won’t function properly. I had some coasting falls when my crank got loose and pushed the button out.
Loosen the lag bolt (the 2.5mm one that you stripped), and unscrew the button until it’s sitting far enough off the hub; usually, the base of the button being about level with the outside of the crank is right. Then lock the button in place with the lag screw.
The way the lag bolt and the Schlupmf slot tool work is, the tool holds the button while you tighten the lag bolt. The slot tool should be applying pressure in the opposite direction from the lag bolt; you are locking the lag bolt to the button, not locking the button to the shaft. Twist them in opposite directions until they are snug.
I only use the schlumpf tool for loosening the buttons. I just use allen key and fingers to tighten each one up so they’re snug, then tighten the allen keys whilst holding the other end button still with an allen key in that. I’ve not had any problems with buttons, either losing them, or getting them too tight since starting to do it this way. (I’ve had one stuck button - put on too tight in assembly before I bought it, and one lost button - my fault for not checking).
No; I ran into this same problem – with two different hubs. The first time, it was due to failed bearings, allowing the center shaft to move and have the gears not align. The second time, it seemed due to my improper frame (hand-dremmeled bearing holders), applying uneven pressure on the bearings. It also seemed to be caused by me tightening the cranks down too tight, causing something on the shaft to catch on the the little inner lip until I hit the button again or loosened the button. The solution for RTL was to use different cranks, and to not tighten them down as much.
However, I think it should never be possible to get the hub into this state – I think you should email Florian/Chris and let them know about the problem. I tried to detail the issue to florian when I was at RTL, but it was difficult to systematically reproduce, and we couldn’t reproduce it while in a KH frame. Hopefully they can solve the issue, as freewheeling is bad!
I had the same problem with this hub on the Triton 36er frame. I emailed KH who put me in touch with Corbin. Based on his advise, I loosened the hub and cranks a bit and added some locktight to the crank shaft. It seemed that excessive tightening of the cranks was putting some pressure on the hub. Every now and again it would just pop into the “free mode” on the downshift 1.5-1, (never the upshift). It hasn’t happened since that action and I’ve put in several hundred miles. For a while I was really hesitant to downshift at any speed because I had some painful UPDs as a result. I hope you get the kinks worked out.
