Cuts in tyre tread, new conti Gp4000s ii

deano802

As it is the summer I put on a new pair of GP4000s ii, only ever ridden 4 seasons before, they feel much nicer but I've done about 200 miles on normal UK roads with them and 2 punctures on the rear in two weeks, possibly through the same cut. I am relatively heavy at 85kg and run them at 100psi. Are these cuts normal? Repairable? Or do I have to replace? Really prefer to repair considering I just laid out for them 3 weeks ago! And if I have to replace I don't really have much confidence in getting another one.

tonysj

Are you riding the same roads as you normally do as those cuts look like you been riding over very rough roads.
Ive had Conti GP4000sii and found them great and hard wearing with the only similar puncture to your pictures was a shard of glass that I had to dig out as it was still embedded in the tyre. I fixed that at the side of the road and got home but later had to put a patch on the inside of the tyre as the cut was causing the inner to force into the cut. Eventually glued , patched and was fine.
Just repair those cuts but check there is nothing still stuck in the tyre that will eventually get forced through causing another puncture.

Regards.

Tony

deano802

TonySJ wrote:

Are you riding the same roads as you normally do as those cuts look like you been riding over very rough roads.
Ive had Conti GP4000sii and found them great and hard wearing with the only similar puncture to your pictures was a shard of glass that I had to dig out as it was still embedded in the tyre. I fixed that at the side of the road and got home but later had to put a patch on the inside of the tyre as the cut was causing the inner to force into the cut. Eventually glued , patched and was fine.
Just repair those cuts but check there is nothing still stuck in the tyre that will eventually get forced through causing another puncture.

Regards.

Tony

Yes normal club runs in the Chilterns, but they are generally poor like all UK roads, I'm not doing gravel or anything like that. What is the best way to repair? What sort of patch and glue can I put on inside of tyre?

milemuncher1

That’s fairly typical of those tyres. They are relatively fragile, when it comes to cuts and the like. Get some glue, and they’ll be fine. You can buy these


http://www.chainreactioncycles.com/mobi ... -prod13249

Or similar, to put on the inside of the tyre, or use something like an empty gel wrapper in an emergency.

StillGoing

Deano802 wrote:

As it is the summer I put on a new pair of GP4000s ii, only ever ridden 4 seasons before, they feel much nicer but I've done about 200 miles on normal UK roads with them and 2 punctures on the rear in two weeks, possibly through the same cut. I am relatively heavy at 85kg and run them at 100psi. Are these cuts normal? Repairable? Or do I have to replace? Really prefer to repair considering I just laid out for them 3 weeks ago! And if I have to replace I don't really have much confidence in getting another one.

Conti GP4000s II are great, probably the best selling clincher these days. I ran them before going tubeless over newly gravelled roads in the wet and dry and they're currently on my wife's hybrid that's ridden off road as much as on. Not a mark on them. Either you've been very unlucky or I've been very lucky, but virtually everyone I ride with uses GP4000s II and haven't had problems.

Tiesetrotter

Yep, that's what happens to them. More money you pay on tyres the easier they cut.

Chilterns like all chalky/flinty areas will eat your tyres.

peat

Riding in the Chilterns after heavy rain is a destructive test of a bicycle tyre.

Anyway, I have used GP4000's for years (summer mainly) and they do cut up. The soft rubber compound that gives you such brilliant grip is also rather fragile. Dems the breaks.

I have treated mine with rubber glue and internal patches (bits of old inner tube or tiptop patches) to prolong life and usually get full wear out of them.

akh

Been riding a set for a couple of thousand kilometers with similar cuts (hit a patch of glass at a junction where there had presumably been a car crash) and they've been absolutely fine. You can repair the insides with special patches like the other poster linked above, but old fashioned inner tube patches, the kind that come with the liquid glue, also work. I find they do cut much more easily than the likes of Gatorskins, but the nice ride and low rolling resistance has to come at some cost.

milemuncher1

AKH wrote:

Been riding a set for a couple of thousand kilometers with similar cuts (hit a patch of glass at a junction where there had presumably been a car crash) and they've been absolutely fine. You can repair the insides with special patches like the other poster linked above, but old fashioned inner tube patches, the kind that come with the liquid glue, also work. I find they do cut much more easily than the likes of Gatorskins, but the nice ride and low rolling resistance has to come at some cost.

^^^
This is spot on.

cougie

What width tyre ?

Admittedly I'm not in the Chilterns but gp4000s are usually pretty bombproof for me and my riding pals.

I'd check there's nothing in the cut and super glue it so nothing else can get into it.

deano802

cougie wrote:

What width tyre ?

Admittedly I'm not in the Chilterns but gp4000s are usually pretty bombproof for me and my riding pals.

I'd check there's nothing in the cut and super glue it so nothing else can get into it.

25mm, the only one that bothers me is the one that you can see the threaded layer through, I think I will go for some patches inside and some rubber glue and I should be OK.

cougie

You don't need 100psi at your weight. You could probably take 20psi out.

deano802

cougie wrote:

You don't need 100psi at your weight. You could probably take 20psi out.

The below is from hunt wheels and others sources seem to have the same general consensus

cougie

I've been on gp4000s since 2005 and a conti mechanic advised me to use the lower pressures. Works for me as I can't even remember the last p*******e.

http://road.cc/content/feature/180830-h ... -pressure-—-balancing-speed-comfort-and-grip

This chart seems more like it. Back tyre has more weight on it so I'd use more psi in it.

I'd not even put 100psi in the 23mm tyres.

Vino'sGhost

Deano802 wrote:

cougie wrote:

You don't need 100psi at your weight. You could probably take 20psi out.

The below is from hunt wheels and others sources seem to have the same general consensus

I think the pressure is about right, I run 23 at 120 on the back 110 on the front. If you drop your pressure by 20 psi you’ll get pinch punctures.

The chilterns are lovely but there’s flint everywhere. At some point you’re going to slice a tyre whatever you’re using but gp4000s 2 are pretty good. I use them all year.

N0bodyOfTheGoat

91/96PSI for an 80Kg rider on "28mm" Conti tyres sounds excessive, especially for the front.

These Conti tyres really measure ~31mm on 17mm internal rim width, good old standard, eh?

I'm ~78Kg; Cube ~9.5Kg; cycling kit inc. shoes ~1.5Kg; water bottles ~2Kg; food/mobile/fairy repair kit etc. ~1Kg... So ~92Kg "all in" when I set off. I use 65-70PSI up front, 85-90PSI at the rear on my "28mm" Conti Grand Sport Races,because I've still not swapped to my new wheels, latex tubes and GP4000 S2s

When I was ~73Kg last summer, I used ~60/80PSI.

Over the last 14 months, I've had four P visits out on the road, three of which have been this spring just after the BOTE2 big thaw.

pastryboy

Some polar opposite experiences here. I find they do cut up fairly badly but I don't worry about it unless it's a big cut. In which case take the tyre off, use sandpaper inside the hole then superglue it and turn tyre inside out for glue to set in place with cut closed up.

At 68kg I run about 85 rear and 80 front on the road, a bit higher in races - rarely puncture.

peat

Do you find they stay closed shut? I go the other way, inflate it to max so the cut is open, fill with rubber glue, then deflate once set.

davep1

I used to use Contis too, but in addition to those cuts I would get tears in the sidewalls through which the inner tube would start to appear. Very disconcerting! I've switched to a Schwalbe of some kind now, need to have a good look at them to check wear, but otherwise I have found them as good as the Contis in every respect, and possibly less punctures. Similar weight to you, and I would run them at 100 psi too.

sungod

i use the contis on my commute bike, they get far more cut up than in your pictures, but typically a couple of years between punctures, usually once they are getting worn

as above, road conditions where you have water + sharp bits are the worst, but at least the contis have good wet grip

unless the carcass is cut enough for the tube to push through or be abraded i just leave it, for a bad cut put a norma rema tube patch on the inside, if the tyre bulges at the cut i bin it

if superglue gets into the carcass fibres it will harden and make inner tube damage more likely, i've tried it on cuts a few times, it never lasted, these days i don't bother