Continental GP4000 Clincher Bead

[Scott!]

I crashed out of a criterium last night. 90 degree right hand turn and went down fast and sudden. Too sudden to register any kind of loss of grip. When I went to rejoin I felt a thumping coming from the rear. Thought it was a bent wheel, but noticed a section of the bead, probably about 10 cm, had unseated from the wheel but maintained pressure. I'm now wondering if the bead was displaced from the crash or if there is a chance it was the cause. Right hand turn, I went down on my right side and the bead popped off on the left side of the wheel. When I told people what had happened, the first question they're asking is if it was a Conti.

I had inflated the tires to 110 psi before leaving the house, air temps were lower last night than the rest of the summer. It's a weekly series and the fourth race on the tire. Wheelset is Mavic R-Sys SLR.

[SDP]

id say displaced by crash ..

[Rick]

Probably happened in the crash. But it can happen on its own theoretically. I had it happen twice, both times on Michelins. that is why I never use them any more.
I have never had it happen on a Conti.
Most people complain that Conti beads are way too tight. I will accept tight as long as they never come off.

[Scott!]

That's perfect, I was about to put a Pro3 on it. Just a bit confused, we use the same crit course every week, and between races and warmups I've probably gone around that turn hundreds of times without drama. Nothing different this time, just wound up on the ground. I thought at first that maybe I was trying to close a gap through the turn and unweighted the rear, but I just looked at my power meter data and I had coasted through the turn, zero cadence, zero power, 22.4 mph to 0 in one second.

[KWalker]

I doubt it was the crash. I had the same thing happen last year during a flat, straight road race and also once during training. This year a teammate had a bead separate during a ride as well. Lastly, a friend had it happen on his first ride on some brand new GP4000s. In all of our cases we felt a lump and a thumping of the wheel and then a loud blow out after. Only my friend with the brand new tires got a warranty replacement.

There is no crash that I'm aware of that would ever rip a bead apart. A clincher would simply pull off of the rim. If it were flat spotted it would have to lock up pretty hard and rip through the entire casing, but that wouldn't involve the bead.

[logy]

Had Hutchinson Fusion blow off Ksyriums on a hot day but never Contis

[WMW]

I'd wager that the great majority of the cases of a tire blowing off are due to tube installation. If a little bit of tube gets caught under the bead, then it can blow the bead off the rim when the opportunity arises... higher temperatures, cornering forces, etc. It's more likely to happen with latex tubes.

[Rick]

I should mention that my problems with Michelins were NOT with the Pro Race 3 or 4. It was probably 10-15 years ago, and I don't remember which model it was.

I actually have used some Michelin Pro Race 3 in the past year. I didn't like them because they wore fast and seemed to cut easily, but they didn't blow off the rim.

[Scott!]

I doubt it was the crash. I had the same thing happen last year during a flat, straight road race and also once during training. This year a teammate had a bead separate during a ride as well. Lastly, a friend had it happen on his first ride on some brand new GP4000s. In all of our cases we felt a lump and a thumping of the wheel and then a loud blow out after. Only my friend with the brand new tires got a warranty replacement.

There is no crash that I'm aware of that would ever rip a bead apart. A clincher would simply pull off of the rim. If it were flat spotted it would have to lock up pretty hard and rip through the entire casing, but that wouldn't involve the bead.

In my case the bead didn't rip apart or separate, it just unseated from the wheel. I released some of the pressure and was able to seat it back onto the wheel with my fingers. Seems fine now, but it did get me thinking about how easy it is to roll Conti's on to my wheels. It makes it easier when changing tires, especially flats on the road, but maybe for peace of mind I'll try something that's a little more difficult to get on. I've put off doing the Michelins because last time I tried to mount them they were a real struggle to get on, but I think I have the motivation now to try them out. I'll probably never know which caused what, but at this point the only variable is the tire, so I'll at least take that out of the equation by replacing it.

[KWalker]

I'm the opposite- Michelins slide on easy but Contis suck.

[NiFTY]

I know this is a thread resurrection but I was wondering if anyone has had any recent experience with conti's debeading. I had one GP4000s that must have pinched 4 tubes (conti supersonic) usually the same night as it was installed. Obviously after the first I assumed I had pinched the tube so was meticulous. After the 4th tube died I threw out the tyre (had done about 60k) and reinstalled a new gp4000s and supersonic tube and have had no issues.

The reason I am now typing this is I replaced the rear tyre on my CLX40s (gp4000s/supersonic tube) rode for about 15k (first 10k sprinting efforts) then was riding tempo heard a tick tick tick while climbing in the saddle. It sounded like the chain was sitting between the sprockets so I went to shift then - Boom. I checked the tyre - no cuts, the tyre was unseated 180 degrees from the valve. Checked the tube - couldn't find an obvious cut but it was dusk. The bead had a few loose threads which i cut short. Have subsequently refit a supersonic tube and done another 60k without issues. Pretty sure the tube was not pinched on the initial installation. Anymore people had issues with debeading of GP 4000s - or can I just put this most recent event down to a fluke?

[Turbopowr]

I ordered 4 GP4000S's from Amazon about a month ago. I had to send one back for a replacement because when I tried mounting it, one part of the bead wouldn't seat properly and I could see the tube trying to pinch through. I tried carefully reseating several times but the tube would keep peeking through when slowly adding air to the tire. I finally removed the tire completely and noticed that there was a defect with the bead. No big deal since Amazon overnighted me a replacement tire and payed to have the defective one sent back. Hopefully it was just a fluke and not a sign of bad/diminishing quality control on Conti's part.

[TheKaiser]

@Turbopowr, can you give us a bit more description of what this defective bead looked like? I see you mention the tube wanted to "pinch through". Does that mean that the tire bead was creeping up and out of the rim as pressure was added, or does it mean that the tire was fully in the rim and the tube would sneak up and around the tire?

Other than the tube escaping, were there any other obvious defects with the tire?

If it was the former, and the tire was creeping up and off the rim under pressure, it sounds like the bead may have been oversized. I have wondered if some of the super cheap sources online are selling "factory 2nds" that failed quality control, so it would be nice if you could spot this somehow.

[addict]

I had the same problems with gp4000s on new zipp404 this spring( first time I decide that made mistake and tube was сatched between bed and tire.. second time it happens on the road @40+mph/ the tire replacement resolve until now..
I can't find any visible issues with defective one(
now inflate to 7.25/6.8 psi instead 8/7.6 (I'm 73 kg)

[Turbopowr]

@TheKaiser, the tire bead was creeping up and out of the rim as pressure was added, but only in the same spot each time.

Here are some pictures I took:



In the future I'll be sure to take a closer look at tires before even trying to mount them on the rim as there was an obvious defect with this tire straight out of the box.