continental gp4000s tyre cuts

gubber12345

I discovered a puncture on my back wheel when I went out to the shed tonight to clean the bike.so took the wheel off,tyre off and blew the tube up to find the hole.couldnt find a hole and the tube stayed up so where did the flat come from,valve wasn't leaking either.discovered a slit/cut on the conti 4000s about 5mm long.

I've had the tyre off completely and no foreign bodies in it but all I can see is the slit.

any ideas as to what could have caused this "ghost" puncture???

will the slit do the tyre any harm? or is it still good to go?

mattyarse

Would the fact that you discovered the tyre deflated suggest it is far from 'good to go''?

gubber12345

mattyarse wrote:

Would the fact that you discovered the tyre deflated suggest it is far from 'good to go''?

i've seen plenty of posts on here about tyres with slits/cuts in them and been told there ok,whats the difference here????????????????

and as I've said I've found nothing on the inside of the tyre,tube back in and wheel staying up so far :!:

mattyarse

Sorry, I may have misread your post, but if you found a deflated tyre and a slit then that seems likely to be connected, although may not be of course.

Gazzetta67

Bought my 1st & (last) set of Conti GP4000s last winter, barely done a 1000 miles when like you i started to get frequent punctures but not cut or slits on tyre until i discovered BOTH tyres were splitting on the sidewall..same place on the tyre along the wire beading. Both tyres ruined. newish sidi shoes ruined as i had to walk 5 miles along a singletrack road with no phone signal. upshot is i WONT buy Conti again and now a pal has had the same problems...maybe a bad batch ? will stick to the tried and trusted michelins.

diy

GP4000S is an amazing tyre that can make you feel like you have new wheels as well as tyres. The downside to the low weight and supple feel is lack of durability. I was getting regular cuts in mine until I switched to Michelin Pro4 Endurance. No where near as nice, but no punctures so far. My GP4000s are currently on my spare wheels and the rear which is cut quite badly is now a turbo trainer tyre.

I would imagine the puncture will show if the tube is pumped up higher.

sungod

rule of thumb

if the tyre doesn't bulge at the cut, it's ok, if it bulges it mens enough of the fabric carcass has been cut to weaken it, you can save it using a commercial or homemade tyre boot, although personally i only do this as a temporary measure

if the cut is all the way through and long enough on the inside, there's a chance the tube may get forced through the cut and eventually hole again, in this case you can save the tyre by patching it on the inside or, again, using a boot

fwiw i've got some big cuts on gp4000s, but still ride them as no bulging etc.

buckles

They are racing tyres. Thus, use them for racing, not general use.

hopak

Gazzetta67 wrote:

Bought my 1st & (last) set of Conti GP4000s last winter, barely done a 1000 miles when like you i started to get frequent punctures but not cut or slits on tyre until i discovered BOTH tyres were splitting on the sidewall..same place on the tyre along the wire beading. Both tyres ruined. newish sidi shoes ruined as i had to walk 5 miles along a singletrack road with no phone signal. upshot is i WONT buy Conti again and now a pal has had the same problems...maybe a bad batch ? will stick to the tried and trusted michelins.

Perhaps this is a bit more than coincidence.
The same happened to me last Sunday.
Three punctures in a month-old, less than 150 miles travelled Conti GP4000S traced it to an 8mm slit just above the bead. I bought a pair of the tyres from Chain Reaction who agreed( to their credit) to replace the defective one without question.
It may be that Conti have a disgruntled employee with a scalpel.

themogulman

8000 miles this year. GP4000s. 0 P*******s.

23mm on my good wheels and 25mm on my training/winter wheels. I tend to run them close to the max PSI.

earth

Buckles wrote:

They are racing tyres. Thus, use them for racing, not general use.

My Veloflex Carbons are a race tyre. At £70 each they are about as race as you can find. I have ridden them for 1000+ miles and there is not a single cut or blemish on the rear tyre.

cougie

I use my Conti GP4000s week in and out. For years they've not let me down. They're the best tyres I've used in 30 years plus.

Going back to the OP - you might have found a slit - but you didn't find a punctured tube. You don't get a flat from just having a small slit in the tyre. Did you feel around inside the tyre ? Did the slit go right through even ?

hopak

cougie wrote:

You don't get a flat from just having a small slit in the tyre. Did you feel around inside the tyre ? Did the slit go right through even ?

I'm sorry but I have to take issue with this. You can get a flat from a small slit. I had three, in the space of one 25 mile ride, all with matching slits in the inner tube.
That's not to say that the Conti 4000S is a rubbish tyre, as I've had the 23mm version on my summer bike for two years without any deflatory (I may have invented a new word here) problems.

cougie

Yes but a small slit doesn't automatically equal a puncture. It has to go all the way through. Yours did.

The OP's probably didn't seeing as he's not found any matching holes.

slowbike

My carbon bike has soft tyres atm - both GP4000s' ... I put it down to not having pumped them up for over 7 weeks - but then I haven't ridden it in that time either.

tubes do leak air - they're only punctured when they leak too much air over the duration of your ride.

phreak

I have GP4s on my turbo bike and haven't had a puncture all year.

earth

The OP does say they pumped up the inner tube expecting it find the hole and but instead found it held air.

That's not really a puncture despite the slit in the tyre. Could be the valve or it could be that it was left to go flat through air leaking through the inner tube as it does. If they were latex inner tubes this would happen over as little as a day.

Can the OP give us more info on this?

gubber12345

its a really strange one,when I checked the tyre(had it completely off and turned inside out)and could find nothing,even at the slit.the slit hasn't gone the whole way through so its confined to the outer shell and I've checked the valve for leakage and its not bubbling when I spit on it.all I can think of is that somebodys maybe playing a trick or something and let it down(only thing I can think of TBH)

the tubes I am using are not top quality tubes just the bargain ones of fleabay,10 for £25 but they've never let me down before and hold the pressure really well,i check them once a week and they usually only need a couple of pumps to bring them back up.until now I couldn't really have faulted the conti's so i'l prob stick with them an see what happens in the near future.

its definitely a weird one.i'l prob put a boot in it to strengthen it at the slit and see what happens.

buckles

earth wrote:

Buckles wrote:

They are racing tyres. Thus, use them for racing, not general use.

My Veloflex Carbons are a race tyre. At £70 each they are about as race as you can find. I have ridden them for 1000+ miles and there is not a single cut or blemish on the rear tyre.

That's great, I'm glad to hear it.

cougie

gubber12345 wrote:

its a really strange one,when I checked the tyre(had it completely off and turned inside out)and could find nothing,even at the slit.the slit hasn't gone the whole way through so its confined to the outer shell and I've checked the valve for leakage and its not bubbling when I spit on it.all I can think of is that somebodys maybe playing a trick or something and let it down(only thing I can think of TBH)

the tubes I am using are not top quality tubes just the bargain ones of fleabay,10 for £25 but they've never let me down before and hold the pressure really well,i check them once a week and they usually only need a couple of pumps to bring them back up.until now I couldn't really have faulted the conti's so i'l prob stick with them an see what happens in the near future.

its definitely a weird one.i'l prob put a boot in it to strengthen it at the slit and see what happens.

If the slit isnt through I'd not bother with the boot. I might bung some rubber glue in there though. Superglue used to work too.

Try pumping the innertube up and then manhandling it round - there must be a hole in there and some kind of angle will open this up - hold it close to your lips and you'll feel the air escaping.

FECES

cougie wrote:

gubber12345 wrote:

its a really strange one,when I checked the tyre(had it completely off and turned inside out)and could find nothing,even at the slit.the slit hasn't gone the whole way through so its confined to the outer shell and I've checked the valve for leakage and its not bubbling when I spit on it.all I can think of is that somebodys maybe playing a trick or something and let it down(only thing I can think of TBH)

the tubes I am using are not top quality tubes just the bargain ones of fleabay,10 for £25 but they've never let me down before and hold the pressure really well,i check them once a week and they usually only need a couple of pumps to bring them back up.until now I couldn't really have faulted the conti's so i'l prob stick with them an see what happens in the near future.

its definitely a weird one.i'l prob put a boot in it to strengthen it at the slit and see what happens.

If the slit isnt through I'd not bother with the boot. I might bung some rubber glue in there though. Superglue used to work too.

Try pumping the innertube up and then manhandling it round - there must be a hole in there and some kind of angle will open this up - hold it close to your lips and you'll feel the air escaping.

**** NO!

The glue hardens and essentially becomes a shard of glass. DONT do it.

keith57

Had three punctures in one day once. Third one was near a friend's house so called in for a cuppa and new tube. My mate took the actual tyre off (GP4000S 25mm) and ran a sharp kitchen knife over the inside and outside of the tyre. Found 2 embedded pieces of glass / stone that we couldn't feel or see by hand/eye. There was a grating noise when the blade went over the embedded thing and careful inspection revealed it well hidden and embedded in the rubber. I do this every time now after a puncture!!

gubber12345

update

after I had left the old tube that I had blown up I went back and found it fat a couple of days later so I believe its a latex tube and the air is actually leaking through the pores of it as somebody else had said earlier.put a new tube in and pumped it p to 110 psi and its still hard and went out for a ride yesterday and no problems to report got through it no probs at all and I was on some crappy side roads.

still keeping an eye on the slit which I hope doesn't get any worse but might put some rubberised glue in it to fill the gap.

yeah heard that before FECES about superglue so wont be doing that.

philbar72

With regards to 4000s tyres and their ability to resist punctures the only thing I’ve witnessed in use where they are completely fallible is thorns. Rose thorns are particularly bad, as they snag and tear through the thickest ply of the tyres carcass, and after yesterdays ride I shall be cutting up the tyre and using it for tyreboots as advised by a club colleague!

The examples I’ve had have both been gradual impact noise or feel after a couple of revolutions of the tyre, then the thorn becomes embedded, and penetrates the tube and you get a slowish puncture. Removal of the thorn is never easy as it perforates the tyre. they pretty much are guaranteed to knacker the tyre though. my last one destroyed a half cm wide setion of the tyre.

cougie

FECES wrote:

cougie wrote:

gubber12345 wrote:

its a really strange one,when I checked the tyre(had it completely off and turned inside out)and could find nothing,even at the slit.the slit hasn't gone the whole way through so its confined to the outer shell and I've checked the valve for leakage and its not bubbling when I spit on it.all I can think of is that somebodys maybe playing a trick or something and let it down(only thing I can think of TBH)

the tubes I am using are not top quality tubes just the bargain ones of fleabay,10 for £25 but they've never let me down before and hold the pressure really well,i check them once a week and they usually only need a couple of pumps to bring them back up.until now I couldn't really have faulted the conti's so i'l prob stick with them an see what happens in the near future.

its definitely a weird one.i'l prob put a boot in it to strengthen it at the slit and see what happens.

If the slit isnt through I'd not bother with the boot. I might bung some rubber glue in there though. Superglue used to work too.

Try pumping the innertube up and then manhandling it round - there must be a hole in there and some kind of angle will open this up - hold it close to your lips and you'll feel the air escaping.

**** NO!

The glue hardens and essentially becomes a shard of glass. DONT do it.

Rubbish - I used to do this regularly with my Michelin Hi Lites - clearly I had more time in those days. Not once did it magically transform into glass.

DavidJB

Buckles wrote:

They are racing tyres. Thus, use them for racing, not general use.

What a load of rollocks...ridden gp4000s through 2 harsh winters and had one puncture....I never use another tyre, I use tubs for racing but have some gp4000s on my spare clinchers.

Best tyre for everything...period.

iPete

Depends where you ride... in London I've found them to be awful for large cuts and splits. According to Strava two went in the bin after 1k miles.

Currently seeing how Vredestein fortezza quattro tricomps cope, so far so good (1.2k miles) but it is all anecdotal and you may well ride in London too!