Schlumpf 2022 Build Questions

Unicycles and Equipment
81

Hello everyone :wave:

Does any one here have a good simple idea on how I can secure this small shim into the 8mm holes drilled into my Flansberrium frames?

I will also ask for @jaco_flans input, given that he’d likely have a clear understanding on if a glue would be viable / safe to use.

The shims fit perfectly but as there is a void below into the fork legs, there’s a risk that it could just fall or be pushed right the way through and be lost forever, rattling around.

I am thinking that holding the shim on a small wooden dowel or pencil end, and then applying an epoxy glue to its edge and the inside edge of the hole, might work.

I’d then aim to push the shim into place upwards, with gravity helping ensure it doesn’t go into the void.

It doesn’t need to be massively strong. Just don’t want it to get lost or end up being pushed in should I ever take the wheel out of the frame and then reinstall it.

Looking at the shim, I’m also now convinced this is needed as I’d not be comfortable running the hubs with their 6mm blocking nub, in an 8mm hole :hole:

I even wondered if there was some kind of expanding foam or substance I could use to block up the void so that the shim was going into a firm/blocked surface.

Well, any ideas welcome :pray: Thanks

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82

I would go the other way and glue it to the spigot on the hub?

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83

Thanks for replying! I see what you mean, but the hub is meant to be 6mm and the frames were the oddity here, being drilled to 8mm when that was the word on the sizing (First they were 6, then 8, then back to 6)

In short I don’t want to tamper with hubs as they’re correct.

84

Hmm, that’s certainly a bit of a dilemma.

I think your idea of expanding foam might be a good one. Just fill up the end of the frame leg. Weight addition will be negligible and it’ll block it up nicely.

No matter how you glue in this spacer I’d expect it to work loose eventually and end up inside your frame, especially if your unicycle ever ends up upside down.

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85

Not fun dilemma. I don’t have any great ideas for a permanent fixture. It seems to me logically that if you would put any expanding foam or similar in there it would not prevent the shim from entering the leg as it would be soft and the forces are probably quite strong on the blocking nub. So if it started moving it would probably just wiggle itself into the foam/frame.

Wonder if the reason that 6mm ended up being the final size was that it is what (likely) makes the hub fit in a Mad4One frame. Or just because it’s simply strong enough to have a 6mm nub.

Hopefully I can soon confirm if the M4O frame fits the hub without drilling.

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(and update the wiki with info 📜 [Wiki] Schlumpf 2022 Hubs - Frame Compatibility ⚙️ - it’s currently a bit outdated as it assumes the nub is 8mm)

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86

Thanks for this! My belief is that the push to go with 6mm was from Kris for his frames. I could have got that mixed up, but that’s how it seemed to me.

I think the 8mm hole was seen as being too big and weakening to the bearing mounts.

Now looking back I wish I’d just had Jakob leave them I drilled as it would have taken a few minutes to drill. But hey ho!

I’m even wondering if using some epoxy putty might be almost better than using the shim:

Quiksteel 16402 Aluminium Reinforced Epoxy Putty, 2 OZ Amazon.co.uk

I could effectively fill in the 8mm hole. Let it cure and then carefully drill back to 6. This still might now be ridge enough for the spigot.

Perhaps there would be a way to install the putty that it could fix and block up the back of the bearing mount void. And then into the 8mm (blocked) space I’d be more confidently able to glue the nice little shim.

Once the shim and hub are installed, I very much doubt it would work itself free, as it has some depth to it, and there’s be a decent fiction for, not to mention the fact that nothing in this spigot area is moving.

I’ve even wondered if I could re-drill the 6mm hole rotated round by a few mm - it wouldn’t be in the dead centre of the bearing mount, but still on the forks.

Maybe I could even find a aluminium welder who’d be able to drop a blob of aluminium solder or whatever is used in this line of work, to allow me to have the metal there again to drill to 6mm as if it had never been drilled?!?

I know Jakob suggested to me before the shim option came up from Florian, that I could drill the hole in the bearing mount cups.

This previously go me thinking why this idea wasn’t the one Florian went with. Why is the hole in the forks?

My belief is that A) the fork side is stronger, and B) and more importantly, by dropping the hub into the frame’s forks and getting the spigot secured there, and then tightening the bearing caps, you’re not concerns of any shift pressures in the spigot. Whereas if you were trying to line up the spigot to the suggested hole in the caps, and then add the forks down on top, you could risk some weirdness as you tighten the caps - as while they’re a nice snug and even fit, it could happen that when one tightens the caps this happens unevenly and works to try and push the bearings (via spigot) out of alignment.

Does anyone notice I’m clearly an over thinker? :joy:

It’s funny how such a small issue and change in specification can in fact cause a bit of a headache to solve.

87

Had you thought of gluing the shim to the hub with a glue that would soften again with the application of heat? (red Locktite?) That way with something like a solder gun you could always heat and remove the shim again in the future if moving the hub to other forks (or indeed leave it there and drill the new fork hole to 8mm).
Seems that if you go with the principle of not gluing it to the hub you are giving yourself lots more headaches.

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88

You know. I think after all you and @MuniEmu were right all along here.

I can also see that removing this small alu shim from the steel bearings and nub wouldn’t likely be that challenging.

You could even file it off if you needed to get it back to native 6mm.

I’d initially balked at the idea of doing anything to my precious hubs, but a glue that is removable would be spot on.

Think I’ve got some red locktite but when I used it before it never seemed to work. But that was likely due to not having an airtight seal.

I may end up going with a thin application or super glue as again I think you’d be able to get it off if needed. With loctite I tend to slightly worry it could leak or seep into areas it shouldn’t.

But thanks. This does in fact seem like an avenue worth investigating :pray:

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89

No you are not - you just want options and do the right thing. I have a tendency to just try something and then re-think it afterwards. Not always a great idea as not everything is reversible :slight_smile:

I also think the solution with attaching the shim to the hub with something that can be removed with heat seems like the best idea so far.

(I just received my tracking number from Schlumpf so I’m also a “tiny bit” excited…)

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90

Woohoo :tada:

I can well imagine. It’s great to see them all flowing out to their new owners.

You’re building yours yourself right? Was it 29”?

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91

Yes I will lace the 29" wheel myself. I have all the parts ready - also for the rest of the Unicycle / although I will borrow the custom (M4O/ISM) saddle setup from my regular 29" or my 36" as it will probably make it easier to feel comfortable if only the gearing is new.

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92

If the shim (6 by 8mm bushing) fits loosely in the frame my suggestion would be to have a new bushing custom made so that it is a friction fit in the frame. A new bushing could be made with a little flare at the top so that is fits into the chamfer of the hole in the frame and this would prevent it from slipping into the frame too far if it works loose over time.

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93

Thanks! That’s given me an idea - I would love to get what you suggest made, but I already feel Florian’s done a lot to help here and he’s a busy man to be asked to make small shims like this.

But I am now wondering if added a very carefully cut round of aluminium foil on this shim itself to bulk it up a bit so that it pressed in with more friction. It might end up looking a be ghetto and over time need re-doing but it could work.

I’ll be having a proper careful tinker once the hubs are back with me, and if this kind of thinking doesn’t work then I’ll go with a removable glue attaching it to the hub itself.

In someways I’ll likely never need removing as one could as was said always drill a frame to 8mm, and I can’t see these hubs moving from the special frames I’ve had built anyway.

So I’m just making it more complex - but there’s the perfectionist in me that would like the frames fork to have a nice, clean and reliable finish at 6mm.

To be clear this likely impacts a few people who ordered frames when the word was it was 8mm.

( cc @Elias )

94

Any local machine shop or capable machinist could make a custom made bushing.

95

@mindbalance mindbalance

I haven’t read all the answers, but I would just drill a 6mm hole in the bearing cap. That way you save weight (like 1/2 a gram but hey) and not chance of slipping. That wont void your warranty, even if you wont need it :sunglasses:

Seems like machining something else to fit over the knob to make it fit in a hole that is too big seems complicated when you have so much space to drill other holes :stuck_out_tongue:

Also, the hole in the bearing cap is 6.5mm on KH frames. Tighter the better but anything between 6 and 6.5 will do really :slight_smile:

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96

I forgot that point. I’ll have to drill into my beautiful Flansberrium frame. But I’m clearly not confident. Yikes! How hard is that? Should I worry I could brake my frame? :scream:

98

I think drilling the bearing cap is in theory not ideal because it “pulls” on one bolt, which could lead to the opposite one loosing tension and untightening, but likely completely fine in practice with some extra loctite. Even more theoretically, it could put some extra stress in the bearing area, but I don’t think it is all that much.
I think drilling the bearing cap is a good first go, if that doesn’t work for some reason, something like loctite 648 and glue the shim onto the hub or the frame (whichever you prefer).

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99

The good thing about drilling the bearing cap is that if it doesn’t work out, you can just get another bearing cap. Maybe there is even a “best” way to reduce any uneven stress on the bearing bolts by drilling the hole closer to one of the bolts (don’t ask me whether that would be towards the front or rear - it does my head in thinking about it).

And on another build issue, I reckon it is well worth having a go at spoking the wheel yourself. Sure, it is hard to be a professional wheel builder, but when (and if) you have the luxury of taking a lot of time to think about it and do it gradually, and get the feel of the spoke tensions and their effect on the trueness of the wheel, you can do an equally good job (but so slow that you would starve if you took on a job as a wheel builder) but you get a great feeling at the end of the process. You do need to get good calculations for the spoke lengths. There are lots of videos on “how to”, and I would suggest getting a junk bicycle wheel and de-spoking, re-spoking it a couple of times as practice before the real thing.

[still waiting for 2nd payment invoice for 100mm 32h - first payment was made in april2022].

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100

Unless an off centered hole is drilled considerably larger then 6mm the bearing could not be installed in the frame or cap. A larger hole would likely not be a good option.

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101

Jim, I agree that your solution would work perfectly and solve the “shim lost inside the frame leg” problem. But I don’t see why a hole in the bottom bearing cap which was not too far away (just a few mm ) from the middle (lowest) part of that bearing cap would have to be “considerably larger” - surely a 6mm hole (well, ok, just a tiny bit wider for “wiggle room”) would fit the standard 6mm hub lug, which doesn’t protrude very far (as long as the hole was centered in the bearing width and had an axis in the radial direction of course)? But it is a moot point, because I doubt that an off-center hole would do much to help the braking “push pull” on the two bearing bolts, which is quite likely not a problem worth worrying about anyway.

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