Tyres - Conti Grand Prix vs Grand Prix 4000s II ?
Comments
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Imposter wrote:Alex99 wrote:If a person fits a tyre that is so unsuitable for the bike in question that it is nearly touching the frame or brake before it's even ridden, then honestly, you tell me what you think is going to happen in court?
Unfortunately, common sense has very little to do with this. My example is obviously a bit alarmist - but the point is valid. If there was even the remotest possibility of tyre companies being sued in this way, they would have addressed it and we would have wall-to-wall warning signs all over the boxes and all over the tyres.
There isn't the remotest possibility of tyre companies being sued in this way. That's why there aren't warnings. This line of thinking neither proves, nor disproves that tyres expand a little.0 -
PhotoNic69 wrote:Ummmm... guys, can we stick to the Topic Title please? If you want to debate about the expansive capacity of tyres which may or may not stretch please start your own thread ;-)
Have a nice day, y'all.....
Have a nice day too. We'll probably just carry on if that's OK?0 -
Alex99 wrote:There isn't the remotest possibility of tyre companies being sued in this way. That's why there aren't warnings. This line of thinking neither proves, nor disproves that tyres expand a little.
You may be right, I don't know. It certainly hasn't happened yet - and if it isn't an issue, then it probably never will happen. The only point I was making was that if tyres do expand through use, then you would hope this is the sort of thing that the manufacturers would be making people aware of - and protecting themselves against - for all kinds of reasons.0 -
Paul Onabike wrote:For normal use I have 23mm grand prix folding on the rear and 23mm GP4000sii on the front. The Standard grand prix doesn't grip quite as well as the sii, but lasts about 3 times longer as the rear. The sii lasts well on the front and gives good grip where you want it, but can cut up a little on winter roads - not enough to be a problem though. It just looks a little disconcerting when you see all the little cuts in the tread. I have to periodically dig out quite a few small flints from the tread, but never had a problem with punctures though.
I found the 4 season to be grippy but terribly short lived on the winter roads, so soon stopped using them.
Never got on with michelin pros, as the ones I had never lasted long enough to wear out - they always got cut up badly early on, rendering them unsafe to use.
The contis expand in width with normal use, a 23 will end up nearer 24-25mm, and a 25 will grow to almost a 28mm wide tyre in a surprisingly short time -so allow for this when choosing a tyre width.
Hey, good news. It turns out that we are allowed to believe our own experience and actual, real life measurements. I for one am relieved. I'll get my callipers out of the bin.0 -
From reading countless reviews on GP4000's it appears that 23mm tyres are closer to 25mm when inflated and 25mm tyres are nearer 28mm when inflated. So is it possible that they have always been that wide and you simply assumed that a 23mm tyre was 23mm wide but when measuring it at some later stage found it to be 25mm (same goes for the 25 tyre) which would be perfectly plausible...0
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MugenSi wrote:From reading countless reviews on GP4000's it appears that 23mm tyres are closer to 25mm when inflated and 25mm tyres are nearer 28mm when inflated. So is it possible that they have always been that wide and you simply assumed that a 23mm tyre was 23mm wide but when measuring it at some later stage found it to be 25mm (same goes for the 25 tyre) which would be perfectly plausible...
My experience is with tyres other than GP4000s, but no, I measure upon initial inflation too.0 -
Of course a tyre is going to inflate to different rates depending on the pressure pumped into it (the inner tube or tubeless). The tyre by its nature is a pliable, flexible, rubberised object with some degree of stretch. You need it to be otherwise we'd be still riding around on solid wooden rim/tyres. OK, the change might not be much but it will vary. If you want a container not to expand when filled with a gas at high pressure it needs to be made of metal and even then, high pressure gas containers will expand or even contract significantly (think of submarines - dramatic changes in vessel size at high pressures). Tyres will change. Agreed?
Sometimes. Maybe. Possibly.
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If you don't fancy the last bit of performance, Grand Prix is a great tyre.
I don't use anything else the last 3 years.
Started with them in the time the 4000s had problems with the sidewalls.0 -
PhotoNic69 wrote:Of course a tyre is going to inflate to different rates depending on the pressure pumped into it (the inner tube or tubeless). The tyre by its nature is a pliable, flexible, rubberised object with some degree of stretch. You need it to be otherwise we'd be still riding around on solid wooden rim/tyres. OK, the change might not be much but it will vary. If you want a container not to expand when filled with a gas at high pressure it needs to be made of metal and even then, high pressure gas containers will expand or even contract significantly (think of submarines - dramatic changes in vessel size at high pressures). Tyres will change. Agreed?
Not sure about the submarine stuff, tbh. Also, tyres are not routinely designed to 'stretch' in the way you describe. Rubber is there for grip and protection, the casing is there to give the tyre structure and uniformity - stretch is not something which manufacturers typically design into the casing, for obvious reasons. Stretch is not the same as flexibility, by the way.
Either way, the GP4K is still an excellent 'all-round' tyre - but then so is the GP.0 -
PhotoNic69 wrote:Of course a tyre is going to inflate to different rates depending on the pressure pumped into it (the inner tube or tubeless). The tyre by its nature is a pliable, flexible, rubberised object with some degree of stretch. You need it to be otherwise we'd be still riding around on solid wooden rim/tyres. OK, the change might not be much but it will vary. If you want a container not to expand when filled with a gas at high pressure it needs to be made of metal and even then, high pressure gas containers will expand or even contract significantly (think of submarines - dramatic changes in vessel size at high pressures). Tyres will change. Agreed?
Yes, agreed. But I was talking about the tyre getting a bit bigger at a constant pressure. So, fit new tyre, pump it up to e.g. 100 psi, measure XX mm, leave for a couple of days, check the pressure again, measure and see XX + 1-2 mm0 -
Imposter wrote:PhotoNic69 wrote:Of course a tyre is going to inflate to different rates depending on the pressure pumped into it (the inner tube or tubeless). The tyre by its nature is a pliable, flexible, rubberised object with some degree of stretch. You need it to be otherwise we'd be still riding around on solid wooden rim/tyres. OK, the change might not be much but it will vary. If you want a container not to expand when filled with a gas at high pressure it needs to be made of metal and even then, high pressure gas containers will expand or even contract significantly (think of submarines - dramatic changes in vessel size at high pressures). Tyres will change. Agreed?
Not sure about the submarine stuff, tbh. Also, tyres are not routinely designed to 'stretch' in the way you describe. Rubber is there for grip and protection, the casing is there to give the tyre structure and uniformity - stretch is not something which manufacturers typically design into the casing, for obvious reasons. Stretch is not the same as flexibility, by the way.
Either way, the GP4K is still an excellent 'all-round' tyre - but then so is the GP.
ALL materials stretch under tension. By how much depends on the material. Manufacturers may not design it in, but since the tyres are of this universe, they will stretch when inflated.0 -
Alex99 wrote:ALL materials stretch under tension. By how much depends on the material.
A material will only stretch if there is sufficient force available to stretch it. Unless that's what you meant?Alex99 wrote:Manufacturers may not design it in, but since the tyres are of this universe, they will stretch when inflated.
Except nobody has ever noticed this, save for a couple of forum members and a vague reference from Schwalbe. That's the bit I'm struggling with. That's not your fault - it's just the way it is.0 -
Imposter wrote:Alex99 wrote:ALL materials stretch under tension. By how much depends on the material.
A material will only stretch if there is sufficient force available to stretch it. Unless that's what you meant?Alex99 wrote:Manufacturers may not design it in, but since the tyres are of this universe, they will stretch when inflated.
Except nobody has ever noticed this, save for a couple of forum members and a vague reference from Schwalbe. That's the bit I'm struggling with. That's not your fault - it's just the way it is.
No, all materials stretch under any force. It is a basic property of matter. The amount of stretch might be small, but it is there.
There are two parts to this discussion which are now getting mixed up. The first is regular elastic stretch. I think this is what PhotoNic69 is writing about. Example, if you inflate a tyre to 100 PSI, it will be bigger than at 50 PSI. It might be a small difference, but it is there. It will also be true of a steel cylinder, a plastic bottle, a glass bottle, a copper boiler, or anything else that you can think of including a submarine (although more likely to be in compression in this case. The principle is the same).
The second thing, is viscoelastic stretch. This is where whatever the container, if you inflate it to say, 100 PSI, then leave it for a lenth of time, the size increases over time, then settles. This isn't going to happen for all materials. For example, it won't happen for steel, concrete and many other materials. This behaviour IS known for polymeric materials. The mechanism is the polymer chains shift away from their normal equilibrium arrangement in response to the applied force, until the forces equal out. This takes a little time, again depending on the polymer.0 -
Alex99 wrote:No, all materials stretch under any force. It is a basic property of matter. The amount of stretch might be small, but it is there.
But only when 'sufficient' force is applied to alter it - that's what I'm saying. Otherwise, hanging a feather off a steel bar would stretch it, which it won't.
Anyway, I'm already conscious that this has gone way off topic, so I'll stop...0 -
Imposter wrote:Alex99 wrote:No, all materials stretch under any force. It is a basic property of matter. The amount of stretch might be small, but it is there.
But only when 'sufficient' force is applied to alter it - that's what I'm saying. Otherwise, hanging a feather off a steel bar would stretch it, which it won't.
Anyway, I'm already conscious that this has gone way off topic, so I'll stop...
"Otherwise, hanging a feather off a steel bar would stretch it, which it won't."
The steel bar would elongate a small amount (strain), obviously within it's elastic limit. When you remove the force, it would return to the original length. Maybe just using the word "stretch" isn't specific enough here.
Cheers for now0 -
OK - so here's the Science Bit.....
I (eventually) received my tyres from CR yesterday and set about swapping out my old Giant SR4 tyres. Before I removed them I made sure they were both inflated to 100psi. I then measured them both at 4 points around the circumference with my calipers (yes, I'm a tool nerd).
The Giants were old but also varied quite a bit from 24-26mm rim to outer circumference of the tyre. Same for cross section.
Next I fitted the Grand Prix GTs and inflated to 100psi. I waited for the length of a cuppa tea then did the same measurements. Both Grand Prix came up to very near to 25mm all around in both depth and cross section. Only about 0.2mm variation.
I'll leave them at 100psi until Friday where I'll deflate and inflate again to 100psi and measure again to see if there has been any 'creep' in the measurements.
Over all I'm very happy with my choice. They seem extremely grippy to the touch. Can't wait to get out on them this weekend.Sometimes. Maybe. Possibly.
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PhotoNic69 wrote:OK - so here's the Science Bit.....
I (eventually) received my tyres from CR yesterday and set about swapping out my old Giant SR4 tyres. Before I removed them I made sure they were both inflated to 100psi. I then measured them both at 4 points around the circumference with my calipers (yes, I'm a tool nerd).
The Giants were old but also varied quite a bit from 24-26mm rim to outer circumference of the tyre. Same for cross section.
Next I fitted the Grand Prix GTs and inflated to 100psi. I waited for the length of a cuppa tea then did the same measurements. Both Grand Prix came up to very near to 25mm all around in both depth and cross section. Only about 0.2mm variation.
I'll leave them at 100psi until Friday where I'll deflate and inflate again to 100psi and measure again to see if there has been any 'creep' in the measurements.
Over all I'm very happy with my choice. They seem extremely grippy to the touch. Can't wait to get out on them this weekend.
Aah, new rubber. Enjoy!0 -
I have run on continue for last ten months and had nothing but puncture after puncture. I won't be buying continue this time. Will try another brand such as vittoria.0
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I rode 25mm 4Seasons for two, er, seasons, and then moved to same size GP4000SMkII. I'm fairly light so run them 65/85psi F/R.
The 4S is as rugged as you get, but feels a good deal stiffer than the 4000S - but only evident to me on changing to the 4000S which feels more supple.
The 4000S is grippier. Wet or dry, cold or warm in my opinion. Which feels slightly contrary to tyre 'technology' normality where best in hot usually equals less best in cold. However, I think the Black Chilli is simply a grippier compound full stop.
The 4000S has much less protection on sidewalls - in fact none. The only tyre loss I have had was on a 4000S down to a large gash in the sidewall - to its credit it did not flat, but needed replacement. The 4S has the Vectran extending bead to bead.
In terms of tread protection I'd say completely equal.
In terms of wear, the 4S appeared lower. Curiously I found the 4S 'nicked' more, but to no ill effect.
In terms of flats, I do 2,500 miles a year and have had one in 4 years - middle of tread on 4000S. My fault as sat against a kerb rocking back and forth on bike waiting for a fried and the back just suddenly went down. Was sitting in a dried pool of mud and clearly rubbish had collected there.0 -
Brian Stax wrote:I have run on continue for last ten months and had nothing but puncture after puncture. I won't be buying continue this time. Will try another brand such as vittoria.
Presumably you mean Continental not 'continue'.
I think it will largely depend on where you live. I have been using one set of 4000s for three years now, one complete summer/winter and two further winters. They're still going strong and I think I may have had two punctures in that time.
Conversely I put some brand new Vittoria Open Corsa's on at the beginning of last summer and towards the end of the summer was getting puncture after puncture and the rear is absolutely shagged! Never buying them again and have just bought a new set of GP 4000's to replace them.
Some people swear by them, some people prefer other brands, the only conclusion I can come to is use what works in your area.0
