That happened when you slammed on the brakes?

What make of rim?

How long were the brakes continuously applied for or did you modulate your braking on and off?

Bad stuff, glad you didn't have an accident. I would be asking for a refund or replacement.

Same thing happened to my Eastons EC90 Carbon Clinchers!

i didn't have the brakes on continuously but more than normal as i was going quicker than the car on a windy but steep hill. i'd heard this happen to a few people but thought they were just riding the brakes all the way down. Matrix wheels, looked the bomb but failed to impress. to be fair the Bike shop has given me a full refund so looking at getting Carbon with alloy braking surface next as don't trust full carbon clinchers any more

YAY CARBON!!! CARBON CARBON CARBON. I don't care, I only want Carbon...

Seriously though, sucks about the wheels. Good on your shop for the refund. Glad you didn't crash. I have 10 year old metal Mavics that have never once failed or broken even with my fat ass riding the brakes down some pretty gnarly descents.

I also have a set of Zipp 404 normal clinchers that are great. I would definitely recommend those.

That is too bad about your rims. But is is a good thing you didn't have a catastrophic rim failure at 65 kph.

For this reason and for others, a better application of carbon rims is with road disc brakes. No heat of any kind is applied to the rims, it is all applied to the disc rotor.

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I've always wondered about disc brakes for road wheels. Are there viable options for this? Are they mountain bike discs, or purpose built road discs?
I guess I could research, but this is way easier...

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It's simple, but it isn't easy.

Yes, there are disc brakes for road use. The best ones that I know of are Avid BB7 brakes. They have 2 versions: one is compatible with mountain brake levers, and the other is compatible with road/STI/doubletap brake levers (the different versions accommodate the differences in cable pull between the levers).

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posts like this make me want to post a picture of my aluminum rims that are cracked

METAL METAL METAL

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

i have seen more carbon breakage then steel/alum in frames,,carbon is new to this game,i have been cycling over 20 years built frames etc, my first carbon part failed pretty quickly. i know all materials fail,but just think of the carbon parts you have seen fail.

Failures I can recall:

seen a cracked steel frame
cracked aluminum rim
cheap carbon seatpost

thats it...got a carbon frame, carbon seatposts, carbon road bars, carbon wheels in the household. they have all been fine. only carbon part ive had break was a cheap seatpost that I overtorqued.

yeah carbon is tricky to do well, wheels need a good epoxy that doesn't melt, layup has to be done right to be strong in all directions.

but then welding metal is tricky too.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

i have about 4 parts made from carbon fork/aerobar couple of rims,,,,have had fork rim break on me SEEN to many carbon frame break to even remember cranks/rims/bars aero and drop/ very expensive rim break for no good reason

Were you using carbon specific brake pads? Did these have a 'lowered' braking surface? I only ask because I have seen the same thing in the same rim (different stickers) happen. But that person was not using carbon specific pads and did not adjust the brake pads to hit the braking surface.

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Brandon Marsh - Website | @BrandonMarshTX | RokaSports | 1stEndurance | ATC Bikeshop |

That would depend on the particular brand. It's for THIS reason alone that Zipp apparently spent a ton of engineering time working with their resin suppliers to find a resin that not only has a high Tg (glass transition temperature - i.e. the temperature it gets "soft") but also exhibits good toughness as well (important for a part of the wheel that may see impacts) before they came out with their 404 and 808 carbon clinchers. Those 2 properties (high Tg and good toughness) are typically competing properties (i.e. "pick one, but not both"), but Zipp managed to find/develop a resin system that gave them both at the same time. You aren't going to get that sort of engineering from some generic wheel brand...

That's also the reason that the 404 and 808 carbon clinchers don't have a rider weight limit. Most (if not all) other carbon clinchers have a rider weight limit in an attempt to prevent the type of rim heating upon braking that caused the sort of deformation you show above.

I hope this failure didn't cause any injury to you...

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That's just ignoring the real issue (poorly engineered carbon rims) and creating a whole 'nuther set of problems...such as aerodynamics and weight, 2 things that are important for road wheels (the aero much more so than the weight, however).

Just engineer the rims properly and use the GIANT disc that is the rim ;-)

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All of these failures everyone is talking about are engineering failures, not material failures...

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good point,but carbon could crack at a place that is not a joint/overlay ,at a point where the stress is to high?

While, as you say, a bicycle rim is essentially a giant disc, it is a disc with some big limitations. For one, whether it be a clincher or tubular rim, it is a thin-walled and very light disc. Then, attached to this giant disc is a very temperature-sensitive device, a clincher tire, or a glued tubular tire. These highly limit the full functionality of the rim as a giant disc rotor.

Also, I have used carbon disc brakes very extensively (in aircraft) and I can say that even highly engineered and highly refined carbon disc brakes have some very significant shortcomings. I have also used disc brakes very extensively on a series of different road bikes. While I would agree that disc brakes are on a bike may not be super aero or super light, they do stop and modulate very, very, very well in a remarkably wide range of harsh and challenging environmental conditions. And those are just mechanical discs. In my experience, disc brakes work far better than any other bicycle brakes in ALL conditions, whether they be on AL or carbon rims. Once you try them, it is very hard to go back.

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That's just ignoring the real issue (poorly engineered carbon rims) and creating a whole 'nuther set of problems...such as aerodynamics and weight

I'm saving this. I may need to use it against you some day down the road. ;-) (Yes, I'm aware that it's not the whole statement.)

Sure...if the design is poorly engineered...but, that's true of ANY material.

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One of the things that is missing in the discussion is that cyclists should understand the capabilities and limitations of the gear they are on. Every single piece of our bikes can and will fail if we take it outside of its performance parameters. Riding 65kph downhill behind a vehicle, grabbing handfuls of brakes is not going to work well for most of these early carbon clinchers (Zipp and maybe the latest Reynolds excepted). And if you do it often, even your aluminum rims are going to wear out at some point. It's not a "good" or "bad" equipment thing. It just is. Accept it. Know the limits of the equipment you're on. Ride accordingly.

And it is not always a "more" or "less" issue between the different materials. Many times it is just that the failure modes are different. Get a tiny dent in your steel top tube? Probably ok to ride on. Aluminum frame? Start looking for a new frame. Carbon? Maybe just a glancing blow...as long as the carbon isn't cracked...ride on.

For the OP...now that you understand the limits of those wheels...you have three choices: 1. Ride your aluminum rims on that course if there is open traffic that might require substantial braking. 2. When finding yourself behind a vehicle like that, pull over and put some distance between you and the vehicle so that you can let the bike roll without braking so much. 3. Spend a lot more $$$$ on wheels engineered to withstand that kind of stress. Only you can answer which of those works best in your own athletic pursuits.



For Tom...I think we can only call them "engineering failures" if we have the performance envelope they were designed to meet in front of us and see that the failure did not exceed the requirement. As you surmised above, I doubt these were designed to the same criteria Zipp used. But surely the manufacturer used some sort of design criteria. Did the OP exceed that criteria? If so...his fault (assuming the manufacturer/vendor did not falsely advertise). If not? Then, yes....perhaps engineering OR quality control failure.

Same thing happened to some Matrix's I was riding. Only mine completely delaminated did one revolution and caught the brake pads on an incredibly steep decent and sent me skidding down the hill. Luckily I only ended up with a few cuts and bruises and was fortunate that a truck stopped and actually took me back to my car.

I think you might underestimate the level of "seat of the pants" design there is in the bike business ;-)

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You're absolutely correct. Truth be told, Tom....I just didn't want to go into that whole side of things. It just would have made my post overly long to make the same point that we ought to know what we're riding. Just because something is round, measures to fit 700, and mounts the tires we want doesn't mean it will do what we're thinking of asking it to do.

Then wouldn't that constitute an engineering failure if you a) failed to properly analyze your design or b) failed to properly spec your design requirements?

  
Bottom line...in this case, without more information...I can't call this an "engineering failure". It might be. It might not be. But Tom is right...this is probably NOT a materials failure. Those materials probably failed exactly as they should be expected to fail.

And I'd bet the disc brakes could be made of carbon!

I'm sure someone at trek or cervelo or tektro or sram or avid has not just started developing a front disc brake that's light and better and should not ever, ever, ever be construed as a fairing. Ever.

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- I do all my own stunts

I dropped some major bucks on a new Zipp Firecrest front race wheel last week and, before I did, I did a LOT of reading about them. I was surprised at how much I found relating to their attention to the rim heating issue. I'd say it shared equal emphasis with the aerodynamic story on the Zipp website and I was surprised by that. Now I get it.

The point I was making is that understanding the properties of the materials you are using, along with the expected use (and abuse) conditions is a part of proper engineering.

As long as the materials ARE what the designer expects them to be (which, depending on the source of the product may not be a good assumption), then any failure would be a failure of engineering...and in the case of the materials not being as expected...well, then I would term that a sourcing failure, and still not a material failure.

Materials are materials and generally behave in predictable ways...

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The whole "know what it's meant to do" is the key, as is - as mentioned by others - exactly who makes the rim, and how. I rode a set of Reynolds DV46Cs (2010 - with the new brake scrim) all last summer, including some very long, steep descents (e.g., in Levi's Gran Fondo). They got really hot but never a single warp or delam or any other issue, and I know other riders up here w/ the same experience. Plus, the non-toroidal shape of the Reynolds makes them very much NOT the new new thing right now, and you can get 'em for a song, in relative terms.

Tom...I guess I am referencing the fact that many manufacturers are listing limits on their wheels for whatever reason, which I'm sure can be explained. I'm sure those limits are due to the lack of engineering for certain "extreme" conditions (heavy riders, excessive braking, etc....I suppose whatever the particular manufacturer intended).

However, it would appear to me you may be correct that this may fall into engineering failure given this, which is what is written about the wheels on their website:


"Constructed to the highest standards, Matrix wheels offer a 2 year limited warranty against manufacture defect. In addition the wheels
have some of the highest rider weight limits in their class with 95kg for the Clinchers and 125kg for the Tubulars. This all accomplished
on wheels with a carbon breaking surface."


The fact that they can't spell braking correctly on their public face doesn't lend a lot of trust that they have a great handle on things. Then again, one of my own and best engineers turned in an Analysis of Alternatives with the phrases "should of" and "could of" in it. The guy can engineer metals like a maniac but can't write above the third grade.

yes i had carbon specific brake pads that came with the wheels and had my LBS realign all the brakes, i didn't have a crash but i think if it had happened to me any earlier in the descent then i would not of had the time to stop. I understand that carbon clinchers are still somewhat in there infancy but was just annoying i had to find out after purchasing and nearly crash to find out. i'm fairly new to bikes (2years) and tried getting as much insight into what wheel to get before i bought them but obviously i'm going to learn from experience now.. just not sure if i was to spend more on the wheels i.e Zipp 404 or similar whether the same thing could happen again. any advise, stay clear from Carbon clinchers? or just step up into the premium market?

Sure...you get what you pay for...

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As you have found out all carbon clincher rims are not created equally and Reynolds has been at the fore front of this market for about 10yrs.The rim has been through improvements with each generation, there are changes from the 2010 rim to the 2011 rim.The 2011 rim runs 100 degrees cooler,new brake lam.and specfic pads.Reynolds even encludes the 1yr. RAP on the 32,46,&66 wheels.
There is no reason to stay away from CC ,I ride the Strikes all the time and even ride them in N.Ga gaps.
You get what you pay for and be aware of the after sale service.

I am on the other end of the spectrum from you having ridden bikes for a really long time. I've ridden a lot of different race wheels. For sponsorship reasons, last year I was on a very basic set of Asian carbon wheels. I personally felt that the difference between those wheels and previous clincher race wheels that I've ridden was quite noticeable. From the balancing of the wheels to the braking quality as well as the 'feel' of the wheels ('speed' of the wheels), not to mention the fact that I had to change pads and adjust the 'height' of the brake pads every time I switched wheels. The previous ones that I had ridden were a set of Zipp aluminum rimmed clinchers, older HED aluminum rimmed clincher wheels, and a newer set of American Classic aluminum rimmed wheels. And, I've ridden several types of tubular wheels.

If I had a limited budget, I would go with a set of basic (inexpensive) tubulars before clinchers. But, if I were to go with clinchers, I would got with a more name brand or one with an aluminum rim even though they are a bit heavier. We have a set of HED Jet 6/9s that are really nice. Or even a set of wheels like the American Classic 420 as they have a nice shallow profile and great hubs. They roll really nicely.

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Brandon Marsh - Website | @BrandonMarshTX | RokaSports | 1stEndurance | ATC Bikeshop |

 
Given you suggested going with inexpensive tubulars, is the over heating threat the same with tubulars as it is with carbon clinchers? Sorry if this is a basic question.

Clutch - and with my apologies for hijacking the thread - I'd love to know more about your experience w/ Strikes? I am about to buy a new set of aero wheels, and I can get a smoking deal (on paper!) on SDV 66 Cs, which is essentially the Strike, but with upgrades spokes, hubs and maybe brake scrim.

Anyway... my impression is that SDVs (and Strikes) are cheap on secondary market right now, because everyone has been 'sold' on the new rim shapes from Zipp and HED (e.g., a SRAM S80 set goes for more on eBay than SDVs, which strikes me as kind of nuts, but anyway...). I totally get that for an unlimited budget, the new CC Zipps are the bomb, and I can totally buy that toroidal rim is faster, and in particular is faster in crosswinds, because the Reynolds profile is so "flat" from the side.

But from a purely practical perspective, SDVs at $1200, weighing 1675g; vs. say HED Jet 6/9 combo, at $1600, weighing 1900g; vs the SRAM S80s for around $1400 and weighing in at 2kg; vs Zipp 606s, probably cost over $2k for the 'old' version (similar weight to HED), or a whopping $2.5k for the Firecrest... Bottom line, I can't afford the Firecrests, or I wouldn't be yammering about it. But since I can't....

In my experience no, carbon tubulars have been around much longer and are more developed than the clinchers. They may heat up similarly, but since the tire does not have to be held on the rim using the structure of the rim (they are glued and there is no 'hook' or 'bead'), one of the biggest issues with clinchers is essentially eliminated. I think that the biggest issue with FULL CARBON clinchers is that they have to be made strong enough to hold the tires on (which is why some have psi limits), and the braking surface has to withstand the heating that can occur. I believe that is why several brands had a 'lowered braking surface' that was in line with the bottom of the rim track where the rim tape goes. It was beefed up a bit, and the heat build up was either dispersed more or at least stayed away from where the tire was held to the rim. Reynolds (used to be Lew I believe) and Zipp are, imho, the leaders in the full carbon clincher market, but the new ENVE wheels are to be nice as well. Yeah, they cost more, but they are probably worth it. There is a pretty long thread on road bike review (longer than I care to read) about the really basic asian carbon clinchers if you want to check that out.

But, those are basically my opinions and my observations. I don't have a close working relationship with any of the companies I mentioned. Rappstar and others have ridden the firecrests. I've only ridden aluminum rimmed clincher race wheels, inexpensive full carbon clincher wheels that I was not impressed with, and several pair of full carbon tubulars of different price ranges. I personally like the convenience of clinchers, so that is why I have chosen them the past few years. Had I known that the performance of the wheels I rode last year would have been what it was, I would have chosen their tubulars.

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Brandon Marsh - Website | @BrandonMarshTX | RokaSports | 1stEndurance | ATC Bikeshop |

 
Ummm...doesn't one need to be concerned about the tubular glue weakening with higher temperatures?

Yeah, the rim won't fail like is shown in the pics that start this thread, but that tubular tire might not stay on in a hard cornering situation...

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Bummer.

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"A wise man once told me......God doesn't call the equipped, he equips the called."

lets all just ride on HED Jets. swapping brake pads around constantly is a pain anyway =)

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

I'm all for only riding equipment that's properly engineered for the expected conditions of use and abuse...and Hed Jets would fall into that category IMHO, along with Zipp CCs, amongst others... ;-)

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if I could afford to have zipp CCs as my training wheels AND race wheels, that would work. because I could leave the carbon pads on =)

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Ask Beloki circa 2003 about melting the glue off some tubulars. I imagine it may be worse with carbon rims because heat will transfer throughout the rim slower and stay localized at the braking surgace

I can't tell what brand these are but not all carbon clinchers are created equal- not by a long shot.

Only one company that I am aware of has done long term (over a year) in-house engineering tests on the effects of braking and heat on the performance and safety.

I got to see some of the on-going Quality Control testing in their manufacturing facility in person.

The others? I'm not sure.

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Tom Demerly
The Tri Shop.com

I would happily ride the wheels in question here in the flat lands of Charleston, SC., Tom. Expected conditions here don't require a lot of braking at all. I could probably ride those wheels into the ground without experiencing the kind of failure pictured.

Not so much if I headed upstate to Hincapie's neighborhood, I guess.

And since I'm kind of partial to that idiot-fest American Zofingen race with the several miles of screaming descent...I'll stick w/the known entities.

... Sounds like they did in fact spell it correctly in this case, though I'd assume inadvertently (or else perhaps their lawyers are just slyly ahead of the curve like that and banking on illiterate consumers... "Liability claim? No way - we told you it would break, right there in black & white! ").

You are correct. I would say that typically most triathletes wouldn't have to worry too much about that...but then again.
- most probably do not put sufficient glue on their tubulars, so they would need to worry...
- most probably use their brakes way too much, so they would need to worry...

But, me personally, I'd still use a more generic carbon tubular over a more generic clincher...and carbon specific pads for either. The pads that we were to use with our wheels this year were very soft green pads. They would wear out pretty quickly with even minimal braking.

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Brandon Marsh - Website | @BrandonMarshTX | RokaSports | 1stEndurance | ATC Bikeshop |

I've seen that crash a couple thousand times and i still say that tire rolled off after he started to skid. I could be wrong, but I'm guessing the majority of the peloton was on Tubulars at that time and they seemed to make it down the Mtn (Including Lance).

I agree though, that excessive heating of the rim is exacerbated by carbon rims. you've got to be careful out there.

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This is your life, and it's ending one minute at a time. - Fight Club
Industry Brat.

Good one!

I agree...then again, a heat-weakened glue bond isn't going to be able to survive as great of a sideways loading like that either...

There was a reason that Miguel "Big Mig" Indurain preferred to run clinchers in the mountains ;-)

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That's reasonable...in a "lesser of 2 evils" sense...

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Absolutely...he "high sided", putting a whole cr@p load of lateral stress on the tire. The crash was not caused by tire roll, but it was exacerbated by it.

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Yeah, I didn't mean to imply that the tire rolled before the skid but that it rolled during/after the skid possibly due to the glue being softened. Who knows if a clincher or a cold tubular would have held, but it still sticks in my mind when I hear someone overheated their tire and then rolled it off the rim

Maybe they actually meant it that way: as in “Sacrificial Breaking Surface”…

(I'm color blind - I hope this is pink)
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Remember Luddites are people too...