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BERD Polymer spokes


Rusevelt
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I've seen these before and feel like because I have trust issues even with carbon parts, these should be a write-off in my head.
It turns out, I'm totally comfortable with them strengthwise, but I could never run them for trials for the fear of scrubbing them against a wall or rock and they start fraying.
No worse than a regular snapped spoke, but still - the idea freaks me out a bit :lol:

Also, more plastic in the ocean for a negligible weight saving. At least metal spokes are just metal and will eventually become nothing. Plus the cost, as you say.

I wonder if they feel different underneath you in terms of stiffness and power transfer?

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Very interesting product, but I'm not sure if it works appropriately for trials with disc brakes. The manufacturer claim these spokes absorb vibrations. Could it mean they'd feel more flexy than steel spokes when you jump on a rear wheel with a locked brake?

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I do wonder about lateral stiffness with these. Imagine a woven lid of a basket it’s rigidity comes from a combination of the rim and weave. In my head a build with these will be relying heavily on the rim for lateral stiffness. A noodly rim like a trials rim is like your basket lid with a shit rim, the whole structure will lack stiffness. Normal spokes interlaced do have a structural stiffness even under no tension. Wheel builders will testify, lace a hub without the rim and the ‘spoke disc’ is actually quite solid. Maybe that’s why you only really see these fabric spokes built on carbon rims. By all means someone please build a stock wheel with these, it’ll be a worthy experiment at best, hilarious YouTube fodder at worst.

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15 hours ago, Maintenance Justice said:

I do wonder about lateral stiffness with these. Imagine a woven lid of a basket it’s rigidity comes from a combination of the rim and weave. In my head a build with these will be relying heavily on the rim for lateral stiffness. A noodly rim like a trials rim is like your basket lid with a shit rim, the whole structure will lack stiffness. Normal spokes interlaced do have a structural stiffness even under no tension. Wheel builders will testify, lace a hub without the rim and the ‘spoke disc’ is actually quite solid. Maybe that’s why you only really see these fabric spokes built on carbon rims. By all means someone please build a stock wheel with these, it’ll be a worthy experiment at best, hilarious YouTube fodder at worst.

In my opinion, trials rims are pretty stiff comparing to lightweight XC and gravel rims seen on many builds with Berd spokes (not only on carbon rims btw). And reviewers of these XC/gravel/enduro wheels say some good things about wheel stiffness. 
My concern is mostly tangential stiffness, that is not so important for MTB, but really important for trials if disc brakes are used. 
Anyway, it would be really interesting if someone built a trials wheel with these spokes. 

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  • 6 months later...

Bit of a bump but... these ended up on my radar again today, and I ended up down a bit of a nerdy spoke rabbit hole for a few hours.

Long story short, I've bought 40m of this and going to attempt to make some, just for personal use: https://southeastsailboats.co.uk/products/marlow-sk99-d12-max-2mm

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Holy labour intensiveness! Very cool, but gosh the effort.

Is there any kind of flexibility on the nipple end (extra-long threaded section or something), or would you have to redo all of them if you change rim to a different ERD?

Curious on the weight savings, and if you can feel any difference once complete :D

Edited by aener
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I remember splicing hemp ropes with my dad for our canal boat, was a little simpler due to only being about 9 cores but yeah, wouldn't fancy doing it for each and every spoke!

We use uhmwpe (trade names of perplas or cestilene) at work for submerged journal bearings, run it on a stainless shaft and you have a completely water proof bearing, it's a pig to machine to tight tolerances though as it's soft as shite :)
Given that it's not a particularly strong material I'm curious as to what gives the rope it's tensile properties?

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3 hours ago, aener said:

Holy labour intensiveness! Very cool, but gosh the effort.

Yeah... ha. Pretty sure this is why Berd charge what they do. Its a lot of labour just to make the spokes! I guess as a DIY project you can write it off as enjoyment.

In related news... for the rim end I'm toying with welded eyelets, so made a crude jig to test the idea. Welding spokes is tricky!

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But comes out ok and pretty repeatable with some practice. They will definitely need load testing though!

 

Berd make the spokes to a length, and I think they glue them to keep everything put when not under tension, but you can quite easily adjust the length of the 'bury' when doing your own. Will need a jig to hold the hub, and a fake spoke hole at X distance away, then make the spokes to fit that.

Weight savings are said to be between 100-200g a wheel, depending on wheel size and previous spoke type. The main thing I'm interested in is ride quality though, apparently they damp vibrations significantly. 

Not really sure how it becomes so strong in tension... This stuff is 12 strand and rated to about 30% more tensile strength than a quality 2.0-1.8-2.0 butted stainless spoke, which is very impressive considering it floats on water! 

 

Also tried the "Chinese finger cuff" technique for fitting a spoke inside the rope. It pulls out with a plain spoke, but if you roll a bunch more thread on there it seems to hold well. Not sure if that will damage the fibres though. More tension will create more clamping force too, as this stuff "collapses inwards" under tension, and it appears to be the method Berd use at the rim end. Investigative times ahead...

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Looking at it, I think the berd nipples are bonded into the rope, there appears to be quite a long straight shank at the nipple end of the rope.

https://www.ridinggravel.com/components/atomik-berd-ultimate-gravel-wheels-getting-rolling/

The close up photo shows what looks like adhesive, perhaps they use a keyed spoke end (more rolled threads would suffice) and thread that with adhesive into the cut end of the rope.  Perhaps it's clamped during curing but with something like methacrylate I would be suprised if you couldn't get a good bond on it as it will key into the fibres of rope as well as the keyed spoke.

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Yeah, there looks to be some sort of gluey stuff. Thanks for the heads up on that, will investigate...

A long rolled thread doesn't work on its own, I just fell on my arse trying :lol:

The welded eyelets works to ~145kg though! Normal spoke tension is about 100, a quick bit of maths reckons one single spoke might see 200kg maximum during a very bodged landing... I plan to make a jig to test that full 200kg load, but for now...

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I'm not sure which methacrylate would work successfully but I would hazard something like loctite AA3038 may do the trick.  I was looking into it for repairing a badly split PE kayak, I ended up welding it in the end but that stuff is what loctite technical put me onto.  I suspect that it wouldn't have proven particularly satisfactory for repairing the kayak due to poor joint mechanics but you should have a pretty good chance if you can slacken the dyneema to form a hollow sleeve that can be filled with adhesive.

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2 hours ago, Adam@TartyBikes said:

Yeah, there looks to be some sort of gluey stuff. Thanks for the heads up on that, will investigate...

A long rolled thread doesn't work on its own, I just fell on my arse trying :lol:

The welded eyelets works to ~145kg though! Normal spoke tension is about 100, a quick bit of maths reckons one single spoke might see 200kg maximum during a very bodged landing... I plan to make a jig to test that full 200kg load, but for now...

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The two of you weighing 145kg makes me feel like a right fat b*****d :lol:

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5 hours ago, Adam@TartyBikes said:

Yeah, there looks to be some sort of gluey stuff. Thanks for the heads up on that, will investigate...

A long rolled thread doesn't work on its own, I just fell on my arse trying :lol:

The welded eyelets works to ~145kg though! Normal spoke tension is about 100, a quick bit of maths reckons one single spoke might see 200kg maximum during a very bodged landing... I plan to make a jig to test that full 200kg load, but for now...

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This has been an entertaining week so far at TB towers. There has been talk of involving vehicles in the testing methods :lol:

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2 hours ago, Adam@TartyBikes said:

Muscle is heavier than fat B)

Yeah, I'd guess that Dave is much stronger, I'm 76kg without ever lifting a weight* or even stepping foot in a gym in my life or doing any significant exercise in the last 4 years.

*that's not to say I haven't lifted heavy things, spent 15 years working on a travelling fairground ride which involves hand mauling 4 tonnes of bits of wood and steel in and out of a box truck.

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Functional fitness / strength is always impressive I find, seems to build less bulky muscle. Just meant that Dave is a beast!

Tested one to 200kg and it holds fine. The eyelet at the 'rim' end has deformed a little though. The spoke stretches by about 3mm at this tension. Normally you'd build an MTB wheel around 100-120kg. The jig below has a 2:1 ratio so the steel spoke is half the tension of the rope one.

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Also tested spoke tension increase after standing on a bike - it was too small to measure. So I think my estimate of 200kg maximum spoke tension during riding (having started at 120kg) is way over what they'll actually see.

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11 minutes ago, Adam@TartyBikes said:

Just meant that Dave is a beast fatty!

:D

I'm thoroughly dissapointed with the safety aspect of the design or your test rig, surely it would be much more entertaining and thrilling to hang a 150kg weight off it and then add your own weight for good measure, perhaps jump up and down on it to simulate shock loading; ensure to get video evidence of the results in order to verify the validity ;)

All joking (wait, who's joking??) aside, it would be interesting to see how well a bonded nipple would hold with various embedment depths and loads.  Are you intending to attempt to load your final design to destruction?

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Get rid of the chocolate and that's a healthy, varied diet isn't it? Think of all the different pizza/curry combinations available...

It keeps the 115kg fire burning over here :lol:

6 hours ago, MadManMike said:

100.6 here :'(

It's almost like I live on chocolate, beer, pizza and curry...

 

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