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Bicycle Experts: Pinch Flats info needed

I run a pair of Conti Grand Prix 4 seasons tyres on my road bike.
They have lasted about 7-8 years easy as I do not ride as a pastime.
Only to commute sometimes.

Now the side wall meshing has started to fray altho the treads are still
strong as ever.

Recently however I got a pinch flat and changed the rear tube....within
a few days I got a pinch flat again. (I always ride with at least 100PSI
tyre pressure although sometimes I am lax in re-filling the tyres)

I this a sign that the tyres need replacing?
 

It's Hedley

Contributor
Greetings Tester28,

First off, I hope all is well in your world.

I ride on Conti GP4000 so cannot say if they are close to being similar. I ride approximately 1500-2000 miles a year for recreation and will change my tires every 2-3 years just for piece of mind. I too inflate in the 100-110 PSI and inflate before each ride or at minimum, every other ride. You would be surprised how quickly tire pressure decreases.

I had one set of GP4000's that was susceptible to pinch flats, but once I replaced them, I never had the issue again. I have no doubt it was human error, but my thought is for $100 or so, the price is worth the upgrade.

If your tire sidewalls have fraying, get new tires. That is dangerous at any speed. It sounds like they are starting to dry rot and a side wall blow out is much more dangerous than a pinch flat at speed.

I will add, when putting in a new tube, give it a bit of air before putting in the tire. This keeps the tube from pinching in the tire before inflating. That causes many pinch flats.

I hope this helps.
 
Hi and thanks for your input on this...it's very helpful.
I am incredibly lax in refilling my tyres...there are times when
I will do it just once a month or only when I feel a bit of softness or wobble
while riding.

Both pinch flats I experienced in rapid succession seem to have happened
around the valve area....I can tell by the loud whoosh I hear in that area when I work the pump.
This leads me to believe that there may be something in the inner wall of the tyre that is
rupturing the tube. Maybe the dry rot has created some sharp surface in there.

I have ordered a pair of new Conti GP 5000s and new Schwalbe tubes. I'll take on board
the advice of inflating the tube a bit before cramming it in the tyre...conti tyres are great
my current pair have served me exceptionally well.
 
I just went from GP 4000S II tires to GP 5000 tires. Love ‘em. I run 25 mm tires now at 110 in the rear and 100 up front. I air up before every other ride. Haven’t pinch flatted since paying closer attention to pressures.

I now ride a Specialized Roubaix. It came with 28 mm tires, which require lower pressure. I pinch flatted three times when I got lax with checking pressures. The sign that I pinch flatted? Snake eye holes in the tube, where the tube was pinched between each wall of the rim and the object I hit (while looking directly at it, thinking, “Don’t hit that!”). One time, both tires went down, and I ran out of CO2 and had to call my wife for a ride. She loves that! 🙄
 
I’ve been wanting to try the gp5000. I have a pair of gp4000 on my bike currently that are a couple summers old. Also have a pair of gator hard shells which for a commuter tire are pretty awesome.
 

tankerjohn

A little poofier than I prefer
Its common for sidewalls to go before the tread wears out. Sounds like you need new tires.
 
Managed to get a pair of GP5000 on today.
Nice tyres....quite different from the GP 4 Seasons. The latter are just so smooth
and easily my favourite.

The GP5000 have noticeably less rolling resistance....they feel a little cushioned and soft at
very low speeds but when you pick up speed, they smoothen out.

I would have preferred Conti 4 seasons but they were all sold out.
 
That's interesting. I would have guessed an all season tire would be a bit more sluggish. The 5000s are a bit faster than the Specialized Turbo Pros I had before, but the Turbo Pros really stick when cornering.
 
I misspoke bigly.
The bike guy had only pumped the tyres to 80psi.
After I set the rear at 110 and the front at 100,
these tyres are like quicksilver.

Now I just hope they resist punctures well.
 
You probably do this, but I always use baby powder (or whathaveyou) when inserting the tube before inflation.
 
I misspoke bigly.
The bike guy had only pumped the tyres to 80psi.
After I set the rear at 110 and the front at 100,
these tyres are like quicksilver.

Now I just hope they resist punctures well.
I was going to mention that they are to be run at a higher psi, but figured you had that covered! Good thing you didn't pinch flat! :p I hope they are puncture resistant, too, but if you check the Conti website, they offer a little less protection. I have had a staple/wire and piece of glass make it through to the tube...
 
You probably do this, but I always use baby powder (or whathaveyou) when inserting the tube before inflation.
I took it to a bike shop where a mechanic threw the tires on for me. He didn't use any powder at all.
What does the powder do?
 
I hope they are puncture resistant, too, but if you check the Conti website, they offer a little less protection. I have had a staple/wire and piece of glass make it through to the tube...
This is why my first choice was the Conti 4 seasons...those things are indestructible.
7 years with no damage....when I took them off the treads were still good but the sidewalls were
crumbly and almost gone.
 
at 100psi I doubt you are pinching..... you would know that you would have felt yourself bottoming out over a hole or rock.

sidewalls fraying is concerning... you need new tires.

if you are seeing a 'snakebite' on the tube, and you are thinking pinch flat.... it may be that you didn't get the tube positioned all the way under the tire and it is pinching upon inflation.

ive never used talc, but in theory it probably does something. I don't use latex tubes either, which are less prone to flats apparently. I don't flat enough to have to try something new.

19 bikes in the house.

I haven't tried the new contis 5000, but like the 4000s enough to have bought a few when the cleared them out
 
I have flatted three times in the last month. Each time I was able to find the culprit. Today was a ground glass fragment. I can't recall how many miles I have on the 5000s, but they are showing some wear, especially in the sidewalls. I might have to find another tire. With all of the debris in the suburbs I think I am going back to a tire with better flat protection.
 
I have flatted three times in the last month. Each time I was able to find the culprit. Today was a ground glass fragment. I can't recall how many miles I have on the 5000s, but they are showing some wear, especially in the sidewalls. I might have to find another tire. With all of the debris in the suburbs I think I am going back to a tire with better flat protection.
The 5000s are going good for me altho it's only been a couple of months. I have revised my behaviour and now
pump them up every 2-3 days religiously. Over 3 days the PSI drops from 100-105 to about 80.

Ive noticed the chilli compound that makes up the bulk of the road surface is a bit sticky and leans towards
being a little 'soft'....Ive no doubt this contributes to the shards it picks up while rolling.
 

BigFoot

Androgynous Pistoleer
Moderator
I just went from GP 4000S II tires to GP 5000 tires. Love ‘em. I run 25 mm tires now at 110 in the rear and 100 up front. I air up before every other ride. Haven’t pinch flatted since paying closer attention to pressures.

I now ride a Specialized Roubaix. It came with 28 mm tires, which require lower pressure. I pinch flatted three times when I got lax with checking pressures. The sign that I pinch flatted? Snake eye holes in the tube, where the tube was pinched between each wall of the rim and the object I hit (while looking directly at it, thinking, “Don’t hit that!”). One time, both tires went down, and I ran out of CO2 and had to call my wife for a ride. She loves that! 🙄
Did you put the 25mm on your Specialized? I was thinking of doing that on my Felt as I will probably need new tires by year end. How much difference could you tell?
 
Did you put the 25mm on your Specialized? I was thinking of doing that on my Felt as I will probably need new tires by year end. How much difference could you tell?
Yes. Specialized likes to do their tires in even numbers, so I had their 24mm Turbo Pros, which measure pretty close to the 25mm Contis, before the 5000s.

How much difference is there? It may be all in my intermediate rider head, but I feel there is less rolling resistance (despite the science saying otherwise), and the bike accelerates faster. I feel the bumps a little more than when I ran 28s at a lower pressure, too.

Not sure which tire I will go to next, but it will be 700x25c.
 
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