Schlumpf hubs: general discussion

[Setonix]

@Klaas Bil

If someone says they don’t feel the play because they always put forward force on the pedals, I dare you to ride a freewheel unicycle and prove it.

Naturally, there is always the situation where you have to hold back a little, but when rolling, the play is less of a problem, than with mounting. What’s a freewheel uni? Do you mean freestyle?

[jogi]

@elpuebloUNIdo

I am hoping that blue loctite is not part of the solution, not for a brand new hub.

The “main” mUni to which you’re referring; is that a Schlumpf? Bottoming out, then continuing to tighten…might have different results, depending on what you’re pushing against. Another rider suggested that further tightening might push against an oil gasket; I don’t have the hub in my possession right now, nor am I that familiar with how the hub is designed, so I can’t speak to that concern.

Silva told me (don’t quote me on this) this problem could be solved, but that it takes a machine shop (they have one) to redesign the spacers.

If there’s a stated specification for tightening (40nM), but that specification can’t be met, then we have a problem. At this point I’d rather be patient and willing to spend money on shipping, to assure that this new item works as it should, rather than pouring blue loctite on the problem.

Thanks for your interest…I’ll keep everyone posted.

1. Silva did not mount the cranks proper
2. Read the f*cking Manual:

"This hub has been tested on both roads and rough terrain with
drops up to 1.5 m. However, due to variables such as rider weight,
skill, riding style, and terrain conditions, it is not possible to war

ranty this hub as fit for a particular level of terrain difficulty or drop
height. While intended for mountain unicycling, it is not appropri-
ate for aggressive freeriding (big drops) or trials.
Do not attempt to dismantle the hub. Doing so will void your warranty.
Use common sense and ride within your limits!

2. Checking crankarms from time to time
Some problems had been reported with crankarms coming lose.
Please make sure, that you have installed and tightened the
crankarms and axle bolts as described before by using a torque
wrench and a torque of 40 - 50 Nm (35 lbft).
Please use some medium strength Loctite to prevent the axle bolt
from coming lose

[juggleaddict]

Anybody know on the second generation hub if there is anything that is supposed to hold on the large bearing covers, or are they just so close to the frame that they won’t fall out of their groove? I was checking the grease in the large bearings today and noticed I didn’t even have to unclip the retaining ring to remove the bearing cover and seal from the large bearing. Is this normal?

[saskatchewanian]

@juggleaddict

Anybody know on the second generation hub if there is anything that is supposed to hold on the large bearing covers, or are they just so close to the frame that they won’t fall out of their groove? I was checking the grease in the large bearings today and noticed I didn’t even have to unclip the retaining ring to remove the bearing cover and seal from the large bearing. Is this normal?

It is supposed to be glued on. The tolerances were so tight that the seals rubbing against the frame and coming loose were pretty common. Most people just cleaned them up, glued them back on and clearanced their frame a little bit afterwards to prevent the rubbing.

[juggleaddict]

Thanks! Any idea on what kind of glue and where to use it? (metal outer cup, metal inner cup, or seal?) Obviously lite so as not to get in the bearings itself! I did notice some residue from something that looked gluey on the drive side, but not the non-drive side, so I may have to go back and glue that one. I originally took the thing apart to see what kind of shape the bearings were in because of a scraping/grainy sound, which I now recognize as that outer bearing cover scraping against the inner and outer metal cups of the large bearing.

[elpuebloUNIdo]

@jogi

2. Read the f*cking Manual:

Read the f*cking thread.

Silva Cycles has a lot of experience installing hubs, and they were only able to tighten the cranks to 18nM before they touched part of the hub. And they had the same problem with another Schlumpf build they were working on at the same time.

[Eric_aus_Chemnitz]

I still do not understand whats wrong when the crank touches the spacer at 18 Nm. What stops you from tightening it the remaining 22 Nm? At which tightening torque would you expect it to touch the crank (40 Nm would be too late!). The spacer is not supposed to just be gently touched by the crank but to be clamped by the crank properly.

[UniDreamerFR]

@Eric aus Chemnitz

I still do not understand whats wrong when the crank touches the spacer at 18 Nm. What stops you from tightening it the remaining 22 Nm? At which tightening torque would you expect it to touch the crank (40 Nm would be too late!). The spacer is not supposed to just be gently touched by the crank but to be clamped by the crank properly.

I also wonder.
On my Quax non geared 36er there is about no torque until the crank reaches the spacer (by memory, I didn’t measure the torque) , and then I put much torque so that the bolt stays at its place.
I don’t understand the issue with the 18Nm stuff.
Maybe the ramp of the spindle (isis like) is too “flat” to keep the crank from slipping , or the spacer is too weak to support the missing torque from 18 to 40 Nm, or it is too large.

[LanceB]

@juggleaddict

Thanks! Any idea on what kind of glue and where to use it? (metal outer cup, metal inner cup, or seal?)

I used gel-type super glue on the inside of the bearing cover. Worked fine for me. (I think that’s what someone else on the forum used, so I just copied them.) It was just the bearing cover on one side. I could see where there was glue there before. It was completely loose, and made a terrible scraping sound as it dragged against the frame. (Sounded worse than it was, but it got my attention!)

[juggleaddict]

@LanceB

I used gel-type super glue on the inside of the bearing cover. Worked fine for me. (I think that’s what someone else on the forum used, so I just copied them.) It was just the bearing cover on one side. I could see where there was glue there before. It was completely loose, and made a terrible scraping sound as it dragged against the frame. (Sounded worse than it was, but it got my attention!)

Thanks I’ll give that a shot. I’m assuming that’s what that residue was that I found on there before. If you happen to need to take the bearing cover off to repack later, is it then permanently sealed on? I would assume you wouldn’t want to use any chemicals to break that bond once it’s made or it may dissolve the bearing cover. Perhaps that sound was just coming from the glue working its way loose and that cover scraping the frame.

[bouin-bouin]

For 2016 Schlumpf, Hub there is only one Size of spacers which is not appropriated considering the dispersion of ISIS standard on both axis and cranks; it’s why spacers are existing In 4, 5, 6, 8, 10mm for non Schlumpf hubs

[Eric_aus_Chemnitz]

@Eric aus Chemnitz

I still do not understand whats wrong when the crank touches the spacer at 18 Nm. What stops you from tightening it the remaining 22 Nm? At which tightening torque would you expect it to touch the crank (40 Nm would be too late!). The spacer is not supposed to just be gently touched by the crank but to be clamped by the crank properly.

@UniDreamerFR

I also wonder.
On my Quax non geared 36er there is about no torque until the crank reaches the spacer (by memory, I didn’t measure the torque) , and then I put much torque so that the bolt stays at its place.
I don’t understand the issue with the 18Nm stuff.
Maybe the ramp of the spindle (isis like) is too “flat” to keep the crank from slipping , or the spacer is too weak to support the missing torque from 18 to 40 Nm, or it is too large.

The 40 Nm are part of the ISIS specification (see here) and not a special Schlumpf phenomenon. ISIS was originally designed with a crank stop, we use spacers as crank stops. It is not specified, at which torque the crank shall touch the cranks stop (spacer) but there is an amount of preload/ press-fit defined in mm.

The crank interface maintains a constant minor diameter bore of 17.90-18.10mm and a constant major diameter of 22.0-22.4mm. The tapered profile of the crank interface exactly matches that of the spindle (1° inclined
angle relative to the spindle axis) with 2 exceptions: the constant major and minor diameters found in the crank interface as just described, and the offset
of the gage lines to produce the required amount of press-fit between the
parts. […] As mentioned above, the interface requires a certain amount of press-fit between the crankarm and spindle. The magnitude of press-fit is defined as the distance between the female shoulder on the crankarm and the male shoulder on the spindle when the crankarm is pressed onto the spindle by hand. […] Each manufacturer must determine the allowable magnitude of the press-fit for their specific crankarm. However, to avoid problems with the crankarm loosening and ensure accurate crankset location, it is recommended that the crankarm “bottom out” against the male shoulder of the spindle prior to reaching the full installation torque specified by the manufacturer. When aluminum alloys are used for the crankarm, a press-fit between 3.0 – 6.0mm has been found to produce the best results.

(see here)

Also:

If a crankarm has too much pre-load it will not bottom out against the crank stop on the spindle when initially installed. This will lead to the crank arm “walking” up the taper during some initial rides and a consequent loosening of the crank bolt. If the bolt is not constantly tightened until the crank finally contacts the stop, the result could be the crank falling off while riding or damage to the interface.

means: too little or no spacer can damage the interface

and:

If the crankarm has too little pre-load it will bottom out on the crank stop prior to attaining a press-fit with the spindle. Depending on the magnitude of the press-fit, this may result in anything from a slight reduction in the load carrying capability of the interface to a “sloppy” fit between the crank and bottom bracket. This may also lead to creaking of the interface due to the slightly “sloppy” fit between crank and spindle.

(see here)

So, if Silva needed 18 Nm to bottom out the crank, it did definitely not bottom out on the crank stop prior to attaining a press-fit with the spindle and everything shall be just fine!

[bouin-bouin]

40Nm Schlumpf specification is for pre-2016 hubs without spacer, I think this too much with a spacer; as soon as you are using a spacer, you don’t need such high tightening torque to avoid loosing your crank

[Eric_aus_Chemnitz]

@bouin-bouin

40Nm Schlumpf specification is for pre-2016 hubs without spacer, I think this too much with a spacer; as soon as you are using a spacer, you don’t need such high tightening torque to avoid loosing your crank

About 40Nm are quite normal for the ISIS interface (the ISIS specification requires a crank stop).

• Park Tool torque recommendations
• FSA instruction
• Bicycle Tutor
• Dimension Bikes instruction

These Bike ISIS interfaces all have an integrated crank stop and are supposed to be torqued around 30 to 45 Nm.

You can tighten cranks against a crank stop (spacer) with higher torque than cranks on a hub without spacers.

[elpuebloUNIdo]

@Eric aus Chemnitz

I still do not understand whats wrong when the crank touches the spacer at 18 Nm. What stops you from tightening it the remaining 22 Nm? At which tightening torque would you expect it to touch the crank (40 Nm would be too late!). The spacer is not supposed to just be gently touched by the crank but to be clamped by the crank properly.

Silva has the unicycle/hub right now, so I cannot answer that question. I am relying on their expertise and the fact that they have installed many Schlumpf hubs in the past. They are the ones who told me that their tentative solution was to re-machine a part (spacer?). When Silva informed me of the problem, my understanding was that this problem would apply to any of the most recent batch of hubs. So, I wanted to share that with the forum.

[bouin-bouin]

Did they Try to fit another set of cranks ?

[elpuebloUNIdo]

@bouin-bouin

Did they Try to fit another set of cranks ?

I don’t know, but I was wondering if a slight change in the cranks could have caused the problem. My guess, based on the fact that their other Schlumpf build experienced the same issue, is that the cranks were not the problem. But, cranks are definitely a place to consider…

[bouin-bouin]

@elpuebloUNIdo

I don’t know, but I was wondering if a slight change in the cranks could have caused the problem. My guess, based on the fact that their other Schlumpf build experienced the same issue, is that the cranks were not the problem. But, cranks are definitely a place to consider…

Schlumpf Hubs have been machined surely In a unique batch
ISIS angle is 1 degree so a small difference on the cranks have great impact on the crank position

[elpuebloUNIdo]

20" Schlumpf Update

I feel a little bit like Chicken Little, screaming “the sky is falling!” Anyhow, I just spoke to SIlva cycles, and now I’m really confused. Last week one of the technicians there said they could only tighten the cranks to 18nM, and today they told me they were now able to tighten it to 40nM. So, I am not sure what to think right now. Again, I’m happy to be working with Silva on this, but I don’t really understand why their evaluation changed. Sorry for freaking anyone out.

[aracer]

@bouin-bouin

For 2016 Schlumpf, Hub there is only one Size of spacers which is not appropriated considering the dispersion of ISIS standard on both axis and cranks; it’s why spacers are existing In 4, 5, 6, 8, 10mm for non Schlumpf hubs

ISIS is a standard - if different cranks need different sized spacers then some of them aren’t meeting the standard. Different sized spacers for different hubs is reasonable, given that the ISIS taper might be positioned differently relative to the bearings. A Schlumpf hub should need a single spacer size for all cranks - the spacer size which provides a crank stop in the right position on the taper according to the ISIS standard.

You certainly don’t need different sized spacers with ISIS in bicycle applications, where you can mount any cranks to any BB with the same crank stop position used for all cranks (I still have ISIS on my mountain bike).

@bouin-bouin

40Nm Schlumpf specification is for pre-2016 hubs without spacer, I think this too much with a spacer; as soon as you are using a spacer, you don’t need such high tightening torque to avoid loosing your crank

What do you imagine the advantage of using a lower torque value to be? I still see reports of people having cranks coming loose using ISIS - a higher torque value helps prevent this.

@elpuebloUNIdo

Silva has the unicycle/hub right now, so I cannot answer that question. I am relying on their expertise and the fact that they have installed many Schlumpf hubs in the past.

I’m not sure if there is Chinese whispers going on here, but as good as they might be, in this case I’m not sure I’d rely on their expertise with previous generation Schlumpfs, given that the ISIS interface has effectively changed, and what might have been necessary and worked before is no longer the case. As several others have queried - exactly what is preventing them from increasing the torque?