Can't speak for other discs, but IME the zipps are only fragile in the sense that if they suffer a side impact, like a wheel axle during shipping, the carbon can crack. But I believe this is non-structural ,or at least, doesn't seem to affect the wheel.

I bought my super-9 clincher lightly used here on slowtwitch, and the seller packed it with a 808 with no protection between them,,,, the axle put two 1 inch cracks in the side of the super 9. I covered them with a valve hole sticker and used the disc for 3-4 years without issue, dead true.

Oh, I should add, I only sold mine because I was building a new bike and was ready for something different. Went with HED Jet 9/6 blacks. Very nice wheels, but in hindsight, I regret selling the Zipps.

So all discs are somewhat fragile.. I was mortified 10 years ago to put my index finger through the Rohacell foam of the original Lightweight disc wheel while I was IN THE BOOTH AT EUROBIKE... I had to buy that wheel and it was pretty terrifying at the time, but highlighted just how fragile those wheels were as I was more trying to guess as to how much epoxy they had flowed onto the Rohacell as that stuff is super delicate, we used it internally in various products at Zipp.. and the answer was that in the name of weight they had almost no resin protecting it (Rohacell is the white foam in the original Lightweight disc, which also is used as core in numerous other brands)

Your second point is probably the most valid... there are no public numbers for sales for all these companies, but for years it was estimated that Zipp discs were 70% of the market.. so even if we take that down to 50% and say there are 10 other brands making the other 50% and then multiply out by 10 years.. it becomes clear that there are just WAY more Zipp discs out in the wild than the other brands.

Lastly, when I was at Zipp, the vast majority of damage we saw and heard about came from flying with bikes..

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So what is inside other brands carbon discs?
Foam???

They're all pretty delicate and agree with others the damage is most often caused while traveling. My 1st disc was a Renn circa 2003 and before 1st use the Philly baggage handlers decided to add a few holes. I covered with stickers included in race swag bag and raced that wheel for a few years without issue until I sold it and bought a Zipp.

Just many more Zipps out there than any other brand.

In some cases, nothing. There are (roughly speaking) two types of disc:
- "foam"-core (nomex honeycomb in the case of Zipp; not sure in the case of others like Renn, that I *think* use this method). FWIW, this is the construction method ENVE has chosen for its new SES disc. The skin here is a stressed skin,

- hollow-core/fairing discs. Some of these wheels are spoked wheels with a fairing bonded on; others are purely a skin bonded between a hub and rim. The main discs that come to mind here are HED and FLO.

The main companies that I can think of that make discs where I'm not 100% sure of construction are:
- FFWD (I think this is a skin only; no core). I've ridden a FFWD front disc and it's a very nice wheel.
- Mavic (I think these are foam core but I don't know).
- Walker Brothers (I think these are hollow, but I'm not sure)
- Campagnolo (I think this is foam core)
- Renn (foam core I think)
- Lightweight
- Corima
- Vision

I'm sure there are others, but most of these seem pretty niche. You see a LOT more discs on the track than at triathlons.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

fwiw can confirm my Walker Bro (Revo) is hollow.

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We use a 1/8 cell Nomex honeycomb core. The only foam we use is at the valve hole and it’s 16 lb. urethane “pour in”.

Thanks, Frank
Renn Multisport

Echo the comments on care when travelling. Touch wood I have only suffered a small dent on my super 9 from a couple of trans pacific flights. Been packing in the wheel section of a scion soft bag.

I have 2 Zipp discs, and have had no problems at all. Granted, when I fly with one, I pack it very well with cardboard sleeves, and padded wheel bags.

FWIW: I seem to recall that the Falcon disc was a hollow design

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Team Zoot-Texas, and Pickle Juice

I had a side impact from something an airline TSA gorilla did by improperly re-packing after inspection. Sent it back to Zipp & they did fix it, slapped some black repair paste on it & didn't do a good job sanding it down, it wasn't flat at all where the patch was. But the hole has been fixed. Aside from that, I haven't had any issues with the Trico Ironcase. As long as you are careful packing it, it is fine. No durability issues. It has kind of a decent thick skin on it.