Pc+ABs is cheaper than nylon+gf.
It is, but not massive difference given how much material is in the core vs cost of the wheel?
For mass scale and tooling is cheaper. Tooling nylon+gf is more expensive than PC/ABS.
Injection molding? What’s their scale of production? I didn’t think there was a mass market for gigantic 120mm urethane wheels 
For nylon+gf it need harder tool steel. They make more than 15k of this wheel already.
I also see prototype for 140mm version. But they no let me taking photo.
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holy shit
Holy shit again…
Makes sense I guess. I was guessing it was gf nylon, wasn’t sure. Since it’s PC abs it kind of makes sense its more brittle in cold
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No friend 
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I see no reason not to take Jeff at his word, that he’s been there and that he knows the ingredients. His facts seem credible. Conventional Cores are injection molded with glass fiber reinforced Nylon. Iwonders cores are injection molded with a Polycarbonate/ABS mixture because it is less expensive to manufacture the molds with softer steel.
So those facts certainly line up with the pictures of the failed cores. Depending on the ratios of PC and ABS, the cores might shrink more after being removed from the mold. This would explain the inconsistent fit with wheel pulleys. The ABS content also explains the poor resistance to the cold and the stress fractures.
So I think it would be fair to say that the i-wonder wheel cores are manufactured with materials that are significantly weaker than conventional wheels–at they same time as they are likely subjected to higher loads due to the large diameter and curved profile. Conventional wheel cores are supported by a relatively dense PU wheel body. I-wonder Cores don’t get that extra support because their wheel bodies are spongy. So we would expect higher loads at the outer edges of the I-wonder cores.
All in all it does not add up to a product that will last. The time to failure would be much shorter with heavy riders, rough terrain, higher speeds and cold weather. Two months and 200 kilometers looks like the shortest time to failure.
Due to inconsistencies in the core thickness and perhaps also the PC/ABS mixture, some wheels may fail much earlier.
Is that a fair summary?
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If correct cooling is not apply when moulding the core it will shrink at different rate. Because they make core in different batch and is now finish winter in China I think this can also be effecting result.
I think it can be fix with some mould change to add some thickness to core. Is easier to adding material to mould than removing so no need new tooling.
So that does not help the people who already bought them.
There are limits to how much thickness can be added to the core given that it needs to accomodate a wheel pulley. PC & ABS just seems to be the wrong choice of materials based on the picture of the failed wheel cores.
If a wheel core does fail while in use, there could be serious injuries.
To me the solution would seem to be to retool and switch to the more expensive Nylon & Glass Fiber material. A recall all of the substandard wheels seems approriate. A recall and replace program would be pretty expensive for the manufacturer. But that would be the right thing to do. That and contacting all customers to warn them of the dangers and to identify factors that increase risk including cold weather, rider weight, etc.
That’s a bit extreme tbh. PC is not exactly a weak material. The ABS is added to PC for flexibility reasons. Maybe these cores cannot be push with as much stress as nylon, but that doesn’t mean that they are “defective” for a recall.
PC is very strong material and have good impact resisting. Adding abs is for extra strong and some flexible. But is not mean is bad.
I think it have less than 1% failure rate for these wheel which can be fairly normal for manufacture in this qty.
Change to nylon+gf is no need and would need too much invest for make new tool and test. Is not possible now.
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I’m going to bow-out because I don’t own any I-wonders. But I do appreciate you sharing your manufacturing knowledge. I learned alot.
Thanks pk
PS. Each eskate has 4 wheels so a 1% failure rate means 4% of riders could experience an injury. 
15,000 units * 1% = 1500 potential injuries. If its 1% in the first year of use, what is the expected failure rate in years 2, 3, etc.
Edit 15000 * .01 = 150 potential injuries in the first year. So not so bad then.
Keep in mind that the wheel is a wear item and not meant to last forever either. And failure rate under 1% doesn’t mean = 1%… could be 0.5%, could be 0.1%… How many people who buy these will be pushing them that hard? And PC is quite strong in most usage. It is used for bulletproof windows after all.
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I think what he meant was MSRP - meaning, IWonder was making a bigger profit on their wheels compared to what some of the US wheelmakers were making. Sold for cheaper in US than shipping from China. Not manufacturing cost.
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Just like the cheap 97mm clone flywheels, this must be why the clones have thicker spokes
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What is your math my guy??? 1% of 15,000 is 150…
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I think failure rate is closer to 0.2% I say is under 1%.
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That means their is 30 bad wheels in the wild if they have made 15k.
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I’m heart broken reading this post.
I recently bought an OwnboardGT carbon, so the version with CloudWheels.
The board feels amazing to ride (it maybe just lack a rear handle to drag it cause that bitch is huge and heavy), and I loved these wheels so much that I was going to buy a pair for my other board with revel kits ; and then I found this post while googling the wheels. I checked and one front wheel of mine has a small crack. For info I weight about 90 kg, probably ride around 100kg cause I usually ride with my back pack. As I said the board is fairly recent, one and a half month, only rode it thrice for noticeable distances (more than 1km or so), for a total of 96,5 kilometers, in an almost lukewarm weather (the coldest ride was maybe 5 or 10°C), on city roads for my commute (so not very harsh condition, some cracks here and there and a little bit of bumpy pavement). I can’t post a picture (cause I’m a new member I guess ?) but I have some.
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