Torque was discussed here
Shifting Latency vs Slop
In the interests of making sure we’re talking about the same thing, there are two factors at play in the unpredictability of shifting. Maybe we can agree on terminology.
There is the difference in time or revolutions between successfully hitting the shifter button and the gears actually shifting. If there is a lot of pressure on the pedals this can take some time. For example: When you are approaching a hill and you attempt to shift from high gear to low gear, if you keep a hard and consistent pressure on the pedals then the gears might take a while before they shift. This shifting will occur during that split second when the pressure is decreased, then “click” you’re in low gear. I don’t have a good term for this delay. “Shifting Latency” doesn’t exactly have much of a ring to it, maybe it’ll work.
The second factor in unpredictability (and for me much more of a problem) is the “slop”. This happens after you hit the button and when the gears are in the act of shifting. There is an unpredictable degree of arc during which your cranks will be free-wheeling. My understanding of this is that the slop will be no greater that 1/12 of a complete revolution (30 degrees max) but yeah it sure FEELS like 1/2 of a revolution. It might only be 1 degree of free wheeling which is really nice and very smooth. But if it is 30 degrees of slop that can get quite scary, especially if you are up shifting while riding down hill and your guni starts to race down hill and out from under you. If the guni picks up that much momentum and the hill is steep then it can require a fair amount of force to stop the wheel and get it back underneath you. Add to that the factor that in high gear the wheel has a bigger advantage of leverage against your legs. Then there’s the bit that you weren’t really expecting this to happen anyway. 30 degrees of slop up shifting while riding downhill is a great recipe for a UPD. In that situation I usually apply the break a little during the whole shifting process. This limits the speed of the free wheeling (slop) phase and also lightens the pressure on the pedals which limits the “shifting latency”.
Does this sound about right? Anybody have a better term than “Shifting Latency”? (Please say “Yes”)
Geoff
1 Like
Geoff, that sounds perfect!
I like Shifting Latency. My best example of it is when trying to shift down when on a downhill. That is when I have most consistent back-pressure on the pedals and it can be many revolutions of trying to hold back the gathering speed of high gear before the down-shift happens (and needs a ‘flick’ or pelvic-thrust to release pressure momentarily, which is hard to control). So I usually try to shift before the downhill starts if I’m not going ride it out in high gear.
I wonder if the feeling of a half-revolution of freewheeling is due to the whole system rotating? So the cranks could really be disengaged for half a revolution of the wheel in motion, but the they only move 30 degrees relative to the hub - they just slide as the whole thing turns. It can be a bit off-putting, but very rarely does it seem to upset my pedalling rhythm. I guess there is a lot of ‘momentum’ in the circular motion of your feet so they will keep going around even if the pressure changes for a split second.
Still, there’s nothing as satisfying as a smooth shift with no detectable slop. It happens maybe 5-10% of the time. Like butter sliding over Teflon. Mmmhmm.
Sam
“The second factor in unpredictability (and for me much more of a problem) is the “slop”. This happens after you hit the button and when the gears are in the act of shifting. There is an unpredictable degree of arc during which your cranks will be free-wheeling. My understanding of this is that the slop will be no greater that 1/12 of a complete revolution (30 degrees max) but yeah it sure FEELS like 1/2 of a revolution.”
my experiance:
using schlumpf grease at temperatures below 0° (my record is -16° ) its up to 2 revolutions.
using sewing machine oil at same temperatures its max 1/4 revolution.
so do the same as in your car - change oil before season changes
but beware, sewing machin oil rinse out, if you bring the hub in warm places as your favourite carpet…
That’s funny because when I sent an email to Florian, moaning about the leaking oil, he replied that they were doing their best to make it suitable for carpet floors, but yet haven’t been successful. 
As we all know by now, all hubs are leaking when oil is used, but I stay with it. Instead of adding 5 ml per year, I add 1 ml every 2nd month. Furthermore, I asked Florian if I can use different oils, like transmission oil (I still had some left from my motorcycle). He replied that almost every oil would be ok.
Sam, I think you’re probably right. The 30 degrees is the motion of the cranks relative to the wheel. If both cranks and wheel are rotating at the same speed (as in low gear) this free-wheeling could go on for awhile, until you force the pedals to go at a different rate. You know, like when you’re free-wheeling downhill and are trying to stop as fast as possible. 
Geoff
Why are there no crank stops in Schlumpf hubs?
Does the lack of crank stops allow for more button travel, and is it possible to damage the hub if crank stops are used (I noticed the stop would butt a c-clip).
sorry. this is the thread I meant to post in -finally!
I had a strange crank problem on one of my geared KH36 Schlumpfs recently: I tightened the cranks (as per spec using my torque wrench) and they were flush against the bearing holders, and even rubbing slightly. This hub is one of the new, slightly wider ones, which had always had >5mm clearance there. Not knowing what else to try, I swapped the cranks for another pair and there is no problem. Looks and rides normal. Both sets of cranks are Moment (first one is 125/150, second set is 150). I’ve done a big ride after this and all is well, but what went wrong? Bad cranks?
Anyway, regardless of all the problems etc, I LOVE my Schlumpf hubs - just hit 1800 miles on my geared 36er. And Beau and I are headed out today for another big group ride.
This summer, our geared 36ers are going to Mongolia! Mine has already been to India and Africa.
—Nathan
You can also look at it the other way: as long as your cranks are rotating within a 30 degree error with the wheel, you apparently have no need to bring the wheel back under you (either forward or backward), because if you did you would not be pedaling so smoothly. When the need to accelerate or decelerate the wheel arises, you will quickly reach the end of the 30-degree leeway and -click- the cranks engage in the new gear. In other words: pedaling for half a wheel rev with disengaged cranks may feel uncomfortable, but isn’t really “dangerous”. Get used to it. Or intently go to the forward or backward limit of the 30-degree leeway.
Nathan fwiw I had this happen in December 2008 with my first hub:
http://unplannedismounts.com/2008/12/22/crank-problems-in-guni-land/
and not surprisingly it continued on when I put the hub in a different wheel:
http://unplannedismounts.com/2009/03/25/moment-eating-schlumpf/
It ate a few pair of cranks like this. It seemed crazy to keep doing this so I emailed Florian who kindly offered to mill a pair of cranks to create more clearance. As it turned out a fellow uni rider in Australia offered to mill a pair of cranks (thanks Ian!) - no issues with clearance now:
http://unplannedismounts.com/2009/09/09/milled-moment-cranks/
My own (uneducated) view puts this problem down to a few things:
- tolerances
- crank material deformation
this problem would not occur imo if the ISIS spec was implemented 100%. Where single speed KH uni’s use a spacer to create a stop shoulder, there is no crank stop shoulder on the geared hub.
A critical component of the interface standard is the use of a crank stop
shoulder on the bottom bracket spindle to ensure consistent axial crankarm
location. These stop shoulders are the datums from which the entire interface
standard is derived
[I]http://www.isisdrive.com/isisdrive/ISIS_Drive_Standard_Document_revD.pdf[/I]
Anyway that is my take on it. The milled cranks did the trick, and I’m loving GUni!
Pete, thanks very much - that’s interesting.
Hey nathan, I was having this problem too at RTL. I mentioned to florian that it seemed due to excessive pressure on the cranks, causing the aluminum to deform. New cranks fixed the problem, and this is one of the reasons I don’t go quite as high as the spec recommended.
But, having said that, I can mill your cranks for you 
corbin
I ended up wondering if I’d inadvertently created a vicious circle of crank problems by significantly over tightening the cranks excessively damaging/deforming the ISIS fittings in the cranks - pic attached of one of the cranks.
I had a fairly average torque wrench at the time. It may or may not have been the root cause of the problem but I decided to replace it with two much better torque wrenches (one for the cranks, one for the lower torque bearing caps etc) before the replacement hub from Florian arrived last September.
Since then no such problems. I use 45Nm on the cranks and check them once a month - they’ve hardly moved at all (weren’t new when fitted) since September. Add in the extra width of the new hub and the milled cranks and frame clearance is all good.
So to clarify. When I get my Schlumph, should I buy new cranks from Florian? I cannot use the cranks I already have? I have several KH Moments now. If the hub has problems and I need to send it in, will I have to use different cranks on my spare (non-GUni) wheel set-up?
The Isis hub is meant to be used with KH cranks. The Schlumpf cranks are all square taper as far as I know. So your Moments should be fine (assuming your getting the muni isis hub).
Thanks. That’s what I thought, but some of the above problems have me wondering.
I will denfinately consider getting one when I have the $$. What was this about a new broken hub, they are pretty expensive and that would be the last thing I would want. Also, how new are these, because lately there have been many threads about them.
The brand new broken Schlumpf story was a bearing problem that affected lots if not all of the previous generation of KH/Schlumpf hubs after only a few kilometers of riding. Schlumpf is still in the process of replacing all the broken hubs. I’m still waiting for my second one. So far it seems the newer model with beefed up bearings is much more reliable than its predecessor. I haven’t had any problems with mine since I got it end of last year. You will probably have to wait a while for yours.
I have some good tech questions regarding Schlumpf Hubs and a disk brake mounted to the AXLE. I have no experience with the hubs as of yet and wonder if anyone here could clarify on this thread or on the thread below:
One suggestion on geared hubs. If you brake through(attached to crank) the gearing, it puts a lot of stress on the gears,you would be using the gears to take up all the braking weight. If you brake at the hub it stops the wheel no gearing involved, and at the price of a geared hub, more undue stress through the gearing could have expensive/catastrophic results.
-Lobbybopster
im just wondering with the disc mounted to the Schlumpf axle wouldn’t there be a little bit of backlash when using the brakes?
if you stop the axle the hub would still have play within the gears and would cause a slight slipping feel,with a HS33 you wouldn’t feel this as bad,because the rim is slowed down.
any input to this?
-filotr14lsdude
If you use a drag brake, what additional strain does it place on the gears that your legs don’t when slowing down?
-KB1JKI