Conti GP4000sII losing sidewall thread

[T42]

In June this year I binned a Conti GP4000sII 700c x 25 because threads from the sidewall were coming loose, catching on the wheel and being ripped out. That tyre had ~4500 km on it.  I replaced it with another of the same, bought at the same time from the same retailer.

That tyre now has ~2500 km, and today I spotted & removed a loose thread from the sidewall.

The brake blocks are not rubbing the sidewall - they engage about 1 mm in from the edge of the rim.

I've been using Conti GP4000sIIs and GP4000s for years, and this is the first time I've had anything go awry.

Anyone able to shed any light?

[sib]

I've experience the same issue (same tyre but 23 width).
Pulled a few threads but no visible damage - still using the tyres.
At least it didn't unravel like a cartoon jumper...

[Genosse Brymbo]

Anyone able to shed any light?

Yes, standard behaviour for Contis.

[CJ]

I have WTB Horizons. The last pair developed the same fraying that you are describing but I hadn't done the same amount of mileage as you. Maybe 500km.

I took a picture and asked WTB if they needed replacing.

They asked me to send them back and provided a new pair under warranty. 10/10 company and I'd recommend as their customer service was excellent. Horizons are great as well.

I'd suggest that you get in touch with Continental to make sure that they are safe and not failing.

[T42]

I'd suggest that you get in touch with Continental to make sure that they are safe and not failing.

Just done this. We'll see what happens.

[Samuel D]

When you say sidewall, is it the casing proper or just the chafer? The chafers on the Schwalbe One slowly unravel over the course of the tyre’s life, accelerating toward the end. I tug them off (in the non-unravelling direction) when I see them. Occasionally a loose strand wraps around the hub axle, so I clear those from time to time too (usually while servicing the bearings). I’ve never had the chafer go dangerously low before the tyre was otherwise done.

[robgul]

Anyone able to shed any light?

Yes, standard behaviour for Contis.

My experience too - they all seem to do it but without failing.

Rob

[andrew_s]

Yes, standard behaviour for Contis.

This.

It's a chafer strip stuck on to protect the tyre itself from the rim hook. It doesn't have a layer of rubber over the top like some other brands, and is consequently prone to loose strands.
If you can be bothered, it's best to cut the loose bits off, rather than just pull, which will unravel round the tyre.

[vorsprung]

Anyone able to shed any light?

Yes, standard behaviour for Contis.

My experience too - they all seem to do it but without failing.

Rob

+1
I've never used GP4000 but all the other Conti tyres I've tried did this.  Annoying but not harmful

[Brucey]

as mentioned above it is almost certainly the chafer coming apart. I have had one tyre (not a conti) that failed in such a way that I think the missing/damaged chafer was responsible; the failure mode was that the tyre split, starting  where the rim touches the part of the tyre that flexes against it.  This caused one of the two plies to fail first, so that the tyre developed a large 'S' shaped wiggle in it before it let go completely. 

I have seen other people's contis develop a similar wiggle and usually, when the tyre was examined the rim had clearly contacted the tyre sidewall directly, (missing/displaced chafer, or badly seated tyre) which most likely started the failure.


I have very often seen the threads from the chafer wrap around the hub and cause the freewheel action to go draggy, and/or wreck the seals on the hub.

cheers

[T42]

OK, thanks everyone.  No further sweat, just scissors.

as mentioned above it is almost certainly the chafer coming apart. I have had one tyre (not a conti) that failed in such a way that I think the missing/damaged chafer was responsible; the failure mode was that the tyre split, starting  where the rim touches the part of the tyre that flexes against it.  This caused one of the two plies to fail first, so that the tyre developed a large 'S' shaped wiggle in it before it let go completely. 

Never had this myself, but it happened to a chum ~10 years ago: after two mysterious flats on the one ride used up his spare tubes, he started in on mine only to have the bead separate and the tube explode through the split with a wonderful bang.

Oh, Conti say to send them the tyre for analysis. Har har: a little googling turns up threads (yes well)  like this one on several forums, so they can't exactly be unaware of the problem. They're expecting that I'll not think it worth the bother, and they're right.

[Samuel D]

I take the view anyway that no part of a tyre including its chafer should greatly outlast the rest. In that way, the ideal tyre – and the Continental Grand Prix 4000 S II is closer to that than most – should be modelled on The Deacon’s Masterpiece:

http://holyjoe.org/poetry/holmes1.htm

Which you’ll find amusing if you haven’t come across it before, T42.

[zigzag]

could this be happening because of washing technique? i used to get the odd tyre fraying when i washed the rims/tyres with a stiff(ish) brush. i now use a sponge which is more gentle and no fraying since. perhaps the brush unglues the chafer which then starts fraying.

[T42]

I take the view anyway that no part of a tyre including its chafer should greatly outlast the rest. In that way, the ideal tyre – and the Continental Grand Prix 4000 S II is closer to that than most – should be modelled on The Deacon’s Masterpiece:

http://holyjoe.org/poetry/holmes1.htm

Which you’ll find amusing if you haven’t come across it before, T42.

Now that is fun. Thank-you, sir.

could this be happening because of washing technique? i used to get the odd tyre fraying when i washed the rims/tyres with a stiff(ish) brush. i now use a sponge which is more gentle and no fraying since. perhaps the brush unglues the chafer which then starts fraying.

Wahs? Wash? What is this strange word?  No. I do occasionally clean my wheels but with a bit of cloth wrapped round a finger and some variety of degreaser; and if I'm feeling really cracked - sorry, enthusiastic - I'll take one of those rim-rubbers over the braking surfaces. While this might be a candidate I'm pretty sure I haven't done it since I mounted this particular tyre.

[Brucey]

Colin Chapman's idea of a perfect racing car was one built light enough that did the race distance and then disintegrated (much as the parson's shay) a few yards after the finish line. BITD regular lotus drivers were of the view that, erm, "the race distance had been underestimated"....

cheers

[andrew_s]

Some time around 15 or 20 years ago Continental had quite a bad reputation for sidewall failures due to misplaced chafer strips - they had reduced the width from 8 mm to 5 mm or something, and the machine that put them on wasn't accurate enough any more.

[rogerzilla]

My Schwalbe Marathon Racers also lose threads enthusiastically.

[T42]

I lose the thread all the time these days.

[FifeingEejit]

Colin Chapman's idea of a perfect racing car was one built light enough that did the race distance and then disintegrated (much as the parson's shay) a few yards after the finish line. BITD regular lotus drivers were of the view that, erm, "the race distance had been underestimated"....

cheers

Holding that view probably lost him a few championships, and he might have outlived a few less of his drivers without it...

"Did I think the Lotus way of doing things was good? No. We had several structural failures in those cars [Indianapolis Lotus 34 and 38]. But at the time, I felt it was the price you paid for getting something significantly better." - Dan Gurney


Oh aye conti's; had that too on some GP4Seasons I was using this summer, I'm used to ripping holes in GP4000SII sidewalls before anything else can fail.

[321up]

We use these on our tandem.  I've occasionally noticed loose threads but they don't seem to be a problem and happens rarely.  Never had a sidewall fail with these tyres.  We ride with fairly high tyre pressure - I think that this is better for the tyre sidewalls.  If the tyre pressure is low the tyre deforms more and could cause more threads to come loose perhaps?

[Brucey]

at  high pressures the carcass flexes less but sees higher mean stress. At lower pressures the tyre flexes more but at lower mean stress.  I think up to a point the former is preferable to the latter.

In some applications the tread wear is so rapid that the carcass isn't so likely to limit the life of the tyre.

cheers