[Closed] Wheelbuilders / bodgers help - broken flange

...oh and before anybody asks, yes I did lace it all the right way in the end.

new hub time

given its a unicycle id relace it at half the number of spokes. only work around for that issue imo

1. Drop a spoke
2. Drill a new hole/weld that piece back on - I doubt it will be that strong - perhaps AL can do it for you with a spoon
3. Get a new hub

How much for hub ?I cannot read the hub well and if it is a unicycle I have no idea how much they cost

Is there enough material to re-lace so that spoke is pulling the other way?

That's the only method I can think of unless you go even more daft with lacing (see my recent thread), or trail rat's idea.

Of course, if you had a spoon and some carbon...

that hub is borked!

I rebuilt a wheel for a guy who had done the same thing, he'd then welded the piece back on with extra weld around the affected area and as soon as i put any tension into the spoke it simply snapped off again.

At the risk of being shot down, just have one spoke missing. I've ridden with one spoke down a few times with no issues (might be luck though).

And I'm sure I'm missing something REALLY obvious, why are there unicycle hubs, why not just use bicycle front hubs?

Seeing as how it's knackered now, I'd drill it 12mm or whatever it is in from the old hole,countersink and fit a one-off spoke that's half inch longer than the rest.

And I'm sure I'm missing something REALLY obvious, why are there unicycle hubs, why not just use bicycle front hubs?

the cranks drive the hub unlike a bicycle front hub.

not only that - this is a schlumph 2 speed i think ......

read UBER expensive .

schlum/ph still in business ? might do something of a deal on a hub shell ?

I rebuilt a wheel for a guy who had done the same thing, he'd then welded the piece back on with extra weld around the affected area and as soon as i put any tension into the spoke it simply snapped off again.

that would be because the weld metal is in an annealed(soft)state,but you could weld it up and get the hub re-heat treated?

my god did i read the price corretly!!??

that would be because the weld metal is in an annealed(soft)state,but you could weld it up and get the hub re-heat treated?

he had re-treated it but to no avail

Actually...fabricate a piece of steel with a hole for a spoke that you can bolt in place under those 2 torx bolts.

I WIN!

or drill a spoke hole to the left and use a longer spoke.

cheap as chips option.

cranks attach to it so needs more strength??

the cranks drive the hub unlike a bicycle front hub.

See, I knew I'd missed something. Doh! 😳

al's plan is not that bad you could use some pretty thick steel there as well

Given the price - for a ****ing unicycle wheel- I would try almost anything

Actually, guys, we are missing a trick:

It's COMPLETELY UNREPAIRABLE, AND YOU CANNOT AFFORD ANOTHER. Time to give up unicycling 😛

trail rat has it - yes mathewshotbolt you did read the price correctly, hence why a new hub isn't an option and I'm happy to try anything to bodge it. I've emailed Schlumpf, but I'm not all that optimistic - they are still in business and making these (some have clearly found out how much a new one costs - I thought I'd let you find out for yourself, but for those who can't be bothered, here's a link http://www.unicycle.uk.com/unicycle-parts/hubs-bearings/kris-holm-schlumpf-geared-unicycle-hub.html), but this is a first generation one which they haven't made for years, so even if replacing the outer shell was possible then I doubt the part is available. There's also lots of gears and stuff inside there, so even if heat treating worked I don't think it's an option.

I'm afraid I have another 3 (cheaper) unicycles, so you're not getting me that easily.

martinxyz - Member
Seeing as how it's knackered now, I'd drill it 12mm or whatever it is in from the old hole,countersink and fit a one-off spoke that's half inch longer than the rest

That's what I would try first.

If not, make a slightly larger stainless steel flange, and use the existing hub holes to bolt it in. Then you need new spokes. But it's all doable at home with a bit of careful bodging, and much cheaper than a new hub.

I like Cynic-al's fix, but in reality I'd just build it with one less spoke, assuming the build's not marginal on strength.

I think the best solution might be to break your other unicycle hubs too.

Several ways to fix that - I'd probably go for drilling another hole.

Bolt a steel plate to the two bolts at the bottom, drill a hole for the spoke in the steel plate and thread the spoke through the hole in the steel plate. Should work.

Would have thought there would have been enough safety margin in that to be a spoke short, the older the gear, the stronger it usually is. They didn't have fancy cad, dynamic modelling in them olden days. Everything was overbuilt.

I don't think there's enough metal to just drill a new hole - as you can just about see in the background, the hub shell is higher the other side of the flange, so I can't actually get very much nearer the center than the existing hole, and it's all cut away between the spoke holes. Though it is interesting that's bencooper's suggested solution, as he's the one person on here who I think actually has one of these hubs, so I'll have another look. Really not at all keen to go with one less spoke, as I don't want to risk the strength of a wheel which has a lot of load, on which I'm not all that stable, but can easily do 15mph+ on. I'll have a think about bolting to the bolts you can see in the picture, but I'd really rather not touch them as I'd be messing with the delicate internals.

If not, make a slightly larger stainless steel flange, and use the existing hub holes to bolt it in. Then you need new spokes. But it's all doable at home with a bit of careful bodging, and much cheaper than a new hub.

I think that's the winner at the moment. I'm wondering whether it might be possible to just take out the spoke to the left of the broken one and bolt a bit of plate to that hole, as the spoke forces ought to mostly balance each other, meaning very little static load on the existing hole, and the highest loading being due simply to decrease in spoke tension as it's ridden. Probably a better solution to take out 3 spokes though to spread the load (if I only take out 2, the force won't be balanced on the plate).

the older the gear, the stronger it usually is. They didn't have fancy cad, dynamic modelling in them olden days. Everything was overbuilt.

Not actually that old at all - less than 10 years I think, just rapidly superseded. Certainly far from overbuilt, quite the opposite - that's the whole problem.

Oh, and thanks for all the help.

Another slightly crazy idea - old Penny Farthing spokes didn't have heads. The spoke started at the rim, threaded into a nipple, went to the hub and dog-legged through a hole, and then out to the rim again.

You'd need to bodge a double-length spoke - I might do it with two spokes threaded at both ends and joined with a long nipple.

Can't you just ignor it? A wheel will be plenty strong enough with only one spoke missing and you should still be able to get it true enough (guessing no rim brakes on a unicycle?)

Another slightly crazy idea - old Penny Farthing spokes didn't have heads. The spoke started at the rim, threaded into a nipple, went to the hub and dog-legged through a hole, and then out to the rim again.

You'd need to bodge a double-length spoke - I might do it with two spokes threaded at both ends and joined with a long nipple.

That would be perfect - much the same as the plate bolted on to the existing intact spoke hole I was thinking about above, but a bit more elegant. Still not quite sure how you're suggesting making one up - where would I get a spoke threaded both ends which was long enough (I think from what you say that one spoke would have to be significantly longer than the current ones)?

andrewh - unfortunately I do plan to have a rim brake - is quite common now on unis with larger wheels. Was rebuilding on a rim with a brake track having just taken off a disc only rim. Would be a lot more comfortable going fast on the downhills if I didn't have to brake with my legs (bearing in mind my legs don't spin at the speed I could freewheel at I have to brake somehow on the downs). Apart from that, having a wobbly wheel doesn't help with stability on a unicycle at 15mph!

Actually I think I'd drill a new hole in the flange. If you file the bottom of the head off the spoke you can drill close to the shell. A whole lot less ball-ache than a plate bolted to the flange.

highest loading being due simply to decrease in spoke tension as it's ridden.

It increases too!

There were quite a few failures with early shlumph parts iirc. My be worth contacting roger at UDC, they might have some odd spare parts. I think I'd probably just ride it with one less spoke if it is for road riding. If you want a 'proper' repair then you could get a new flange laser cut. Basically an annulus with two concentric rings of holes: one set for some m3 bolt to fix into the existing spoke holes and a new set of holes for the spokes. You'll probably get away with same spokes and it would only cost £10-£20.

Still not quite sure how you're suggesting making one up - where would I get a spoke threaded both ends which was long enough

Wheel building specialists should be able to roll a thread on to custom spoke lengths for you*. Just get plenty of thread put on the rim end of the folded spoke to give you something to work with, then trim excess spoke off when you've got the length right.

* or get one of the longest spokes you can (un-butted obviously, otherwise you could end up with a butted width bent over and sitting in the flange hole). DT Champions available up to 314mm, so bags of spare even for a 29er wheel build. Just get the wheel shop to snip the elbow off and put a thread at that end. Put the bend where you calculate and then get a normal short spoke and again snip the elbow off and have a thread added.

As there were quite a few failures with the internals of these hubs I would expect that somebody would have a shell kicking around. Either that or ride it with a spoke down, it shouldn't be a problem.

I get custom spokes from Central Wheel in Birmingham - they cut them from big coils of wire so I'm sure if you talk to them they could make you a long bit of wire with a thread at both ends.

If you want a 'proper' repair then you could get a new flange laser cut. Basically an annulus with two concentric rings of holes: one set for some m3 bolt to fix into the existing spoke holes and a new set of holes for the spokes. You'll probably get away with same spokes and it would only cost £10-£20.

Where would I get to make me one of those? I like the sound of a proper repair, and in the context £20 is an absolute bargain.

Wheel building specialists should be able to roll a thread on to custom spoke lengths for you

Any suggestions? That also sounds like a definite plan, and a pretty immediate fix. At the worst it's definitely preferable to riding with one spoke missing.

Edit: missed ben's reply when replying myself - Central Wheel could presumably make me a single spoke the right length if cutting from a roll, so that sounds the best plan. Have just spoken to them and waiting for them to get back to me...

Where would I get to make me one of those? I like the sound of a proper repair, and in the context £20 is an absolute bargain.

First draw it in CAD and export as a DXF. Can you do this or know someone who can? Then fire it off to a few laser cutting firms for a price. You need to find one that will do a small order. I have a couple local to me or some will do it all on line and post the piece.

If you get stuck getting it drawn I could probably help, in fact I'm drawing some parts up for laser cutting today.

Price is an estimate but these light plates were £7 each for example, similar size, a few less holes:
[img] [/img]
[url= http://www.w19design.co.uk/exhibitions/science_oxford/ ]Light plates for interactive exhibit[/url]

Bah - Central Wheel say they don't do 14G as they only do motorbike spokes which are thicker. What sort of custom spokes do you get from them, ben - did I ask the wrong question? I suppose I could go to 13G if they'd do that (I didn't ask), but it would make threading it through the hub a lot more difficult - 14G has to be preferable.

I didn't read all the content.

Wheels are in balance, right? Spokes all pulling different ways, but equalling out. So if you've over-stressed one point, could there be damage elsewhere? I think it's worth stripping and inspecting carefully before you spend more time and money on it.

This is the sort of thing I was thinking:

[img] [/img]

You might have to play with the outer hole positions a little to keep the same length spokes, and the inner pattern is just an approximation.

Bah - Central Wheel say they don't do 14G as they only do motorbike spokes which are thicker.

I get 14G spokes from them all the time 😉

Have you got a contact there I could try - the response I got back was that they didn't do 14g - I tried mentioning that you'd put me on to them and you got bike spokes from them (sorry!) but it didn't help. Though I did notice http://www.centralwirecomponents.co.uk/ where they say they can do 2mm threaded rods up to 1500mm long. Always assuming they didn't just decide they weren't interested in just making one spoke and fobbing me off...

So is there anything special about the wire used to make spokes? Found http://www.ebay.co.uk/itm/STAINLESS-STEEL-ROUND-BAR-ROD-2mm-DIA-900mm-LONG-/390412311859 - all I'd then need to find is somebody who can roll threads (I'm assuming cutting to length isn't a problem, and that making the bends might be tricky, but not too difficult). Anything wrong with that plan?

Do you know anybody local who can roll threads, Stoner?

I just ordered another 500 14G spokes from Central Wheel - they're always a bit, well, "random" on the phone 😉

Spoke steel is not standard stainless - you might find that too brittle.

You could also try Dylan at yourspokes.co.uk - I think he mostly cuts down spokes on a Phil Wood machine, but he might have some ideas.

all I'd then need to find is somebody who can roll threads

I'd try your LBS - we have a tool for rolling threads on spokes.

There is a laser cutter place near me that will do a one off piece
never used them but no folk who have for random bits

Happy to use them and then post to you if any use
E-mail in profile etc

I just ordered another 500 14G spokes from Central Wheel - they're always a bit, well, "random" on the phone

Is e-mail likely to be any better?

Spoke steel is not standard stainless

That's what I was afraid of.

could you not just weld a spoke to the other spokes where they cross?

Out of interest, how many spokes on that? ( normally, I mean?)

Oh, and thanks for all the help, nickjb (and others) on the custom flange. I've not ruled that out as in a way it looks an excellent solution taking the stress on the new plate rather than the existing flange. Just that if I can get a custom double ended spoke made it's a mush easier fix - I don't even need to rebuild the rest of the wheel (though I've already dropped the tension a bit). I've got no recent CAD experience (the last time I used it was I think autocad on a 286!), but I'm sure I could manage to work it out. In order to keep the correct spoke pattern I think I'd have to have both sets of holes one above the other rather than offset as you show (which should also keep much the same spoke length).

36 spokes normally - 35 at the moment 😉

You could even it out and lace it 32 3 cross . It would be plenty strong enough* but on reflection, which holes would you leave and you'd end up with at least 3 spoke lengths and it would look weird, and would probably stress it a bit much.... Bodge too far...?

* I've no idea how much you weigh, how much stick your giving the wheel...

I'd be leaving it, once it settles down probably won't make masses of difference

What about a little bracket off the nearby bolts like this:

[IMG] :original[/IMG]

nickjb - Member
This is the sort of thing I was thinking:

That's more or less what I was suggesting, just a DIY man in a shed with hand tools effort. You can do it yourself with a flat piece of stainless.

Start by scribing a circle the same as the PCD of your existing hub, and another for the new spoke holes. DIvide the circle up into 10º segments and punch mark where you want the holes. Then cut the steel. That's the laborious bit - I'd probably use a cutting wheel to rough it out. Then a few hours with a smaller grinder and files and you have the shape right. No point drilling the holes before this in case you scrap the steel. Don't forget to countersink the new spoke holes.

You'll have to bed it into the existing hub because there's probably an angle there. Epoxy and a suitable filler will do that job.

If an old disk was the right diameter, that may save some time, but more likely it will have pre-existing slots etc that interfere with your drillings.

DIvide the circle up into 10º segments

It's not a 72 spoke wheel 😉

f an old disk was the right diameter, that may save some time

I have an unused 140 I think - but even that will be too big even for this large flange hub (shd 92mm).

I was intending that the new spokes be between the old holes - should have been clearer.

Edit:

GeForce Junky - Member
What about a little bracket off the nearby bolts like this:

Actually that looks like an even better idea.

I was intending that the new spokes be between the old holes

Ah - but as I commented above, the new spoke holes need to be above the existing ones (unless I make a flange for both sides) so that the pattern is right.

Actually that looks like an even better idea.

unless I make a flange for both sides

Actually that looks like an even better idea.

Better if you are hand fettling, but not if you are going for a laser cut. For £20 is it really worth spending a few hours with a file

I agree - if I really can get one (or two) for £20 then that's a lot better than putting off making one myself for ages. I was originally thinking bodge (and actually coming round to al's idea - that would work with a bit of care), but either the new flange or the double ended spoke are a lot more elegant - currently still pursuing the latter.

I love how useful STW is for stuff like this - would never have come up with some of those ideas myself - thanks chaps.

Junkyard - Member
...if you are hand fettling, but not if you are going for a laser cut. For £20 is it really worth spending a few hours with a file

Well the hand fettling job could be over and done with tonight, and obviously the laser cut job would look neater, but where's the fun in that? 🙂

Well the hand fettling job could be over and done with tonight

if I had the right metal I'd be on it already, at least as an interim fix

I just ordered another 500 14G spokes from Central Wheel

Is there more than one "Central Wheel" in Birmingham, ben? I just had an email back from Central Wheel Components Ltd which said:

nobody has ordered a “load” of 14 Gauge spokes from CWC in eons

The place I tried is http://www.central-wheel.co.uk/ - is there some other company who does spokes I'm missing?

<bangs head against wall>

I can't believe I didn't try the obvious place earlier - it looks an awful lot like they'll be able to supply exactly what I need, and won't have an issue with selling me just one spoke (I've spent plenty of money there already!) I shall phone Roger tomorrow.

http://www.unicycle.uk.com/unicycle-parts/spokes/penny-farthing-spoke-blanks.html
http://www.unicycle.uk.com/spoke-cutting-and-threading-service.html