The strange case of the Continental Grand Prix 5000 TL

[Samuel D]

The new Grand Prix 5000-series tyres have been tested to be very fast indeed, but I wonder if Continental got there without consequence. That would seem too good to be true. Wet grip, maybe?

But it’s the tubeless TL model that intrigues me. It has a lower TPI casing, more weight, and yet tests fractionally faster than the tubed model (even extrapolating for a latex tube). That’s odd. It’s odder still in combination with Continental’s claims about stiff sidewalls.

I think we’re seeing something else at play here. I think the sidewalls are indeed stiffer than usual but have low energy losses despite that due to low-hysteresis materials. This would allow the tyre to test fast on rollers (in part by having less roller indentation at the contact patch and thus less energy loss in the higher-hysteresis tread rubber), but any user would have to run lower pressures than usual to arrive at their desired level of comfort and suspension (the latter greatly affecting speed on real roads, remember). And at those lower pressures, the Crr goes up to about the levels you’d expect.

We’ve seen hints of this in the past with open tubular cotton tyres seeming faster and/or more comfortable in the real world than they test on rollers, compared to vulcanised clinchers with more substantial anti-puncture strips.

Being cynical about Continental’s marketing ethos, I even wonder if this tyre is a concerted attempt to game the Crr testers. Otherwise why try to make the sidewalls stiff?

Note that I’m not saying this isn’t a very fast tyre and perhaps progress by a balance of performance metrics.

Your thoughts?

[philvantwo]

Nobody on here will pay that much for a tyre! I had 2 of the 4000s fail on the sidewalls, I'll stick to my Gatorskins at £23 from the wiggle thanks.

[Cugel]

The new Grand Prix 5000-series tyres have been tested to be very fast indeed, but I wonder if Continental got there without consequence. That would seem too good to be true. Wet grip, maybe?

But it’s the tubeless TL model that intrigues me. It has a lower TPI casing, more weight, and yet tests fractionally faster than the tubed model (even extrapolating for a latex tube). That’s odd. It’s odder still in combination with Continental’s claims about stiff sidewalls.

I think we’re seeing something else at play here. I think the sidewalls are indeed stiffer than usual but have low energy losses despite that due to low-hysteresis materials. This would allow the tyre to test fast on rollers (in part by having less roller indentation at the contact patch and thus less energy loss in the higher-hysteresis tread rubber), but any user would have to run lower pressures than usual to arrive at their desired level of comfort and suspension (the latter greatly affecting speed on real roads, remember). And at those lower pressures, the Crr goes up to about the levels you’d expect.

We’ve seen hints of this in the past with open tubular cotton tyres seeming faster and/or more comfortable in the real world than they test on rollers, compared to vulcanised clinchers with more substantial anti-puncture strips.

Being cynical about Continental’s marketing ethos, I even wonder if this tyre is a concerted attempt to game the Crr testers. Otherwise why try to make the sidewalls stiff?

Note that I’m not saying this isn’t a very fast tyre and perhaps progress by a balance of performance metrics.

Your thoughts?

Your logic and extrapolations of the tyre design factors all hangs together. But how many of the assumptions involved are true?

There are many reasons to doubt the tyre manufacturer advert-reasoning; and that of the magazine/website "testers". As we know, adverts can impart information that is economical with the truth. Magazine and website testers may well have been suborned by these economies, one way or another. Test regimes are often adverts in disguise.

The best "test" is to use them yourself in the real world, in the way that you do other tyres, in your personal style or context of cycling. Alas, this is expensive and so we end up reading the adverts and website "tests" anyway then hunting for real-person commentary from those who have bought the things.

Then we come to another difficulty. Those who buy things (including me & you probably) tend to justify their purchase by over-praise and even an ignore of any small issues. Only large issues will persuade many to make a less than complimentary comment. We do not like to feel we have been duped by a spiv.

How difficult it is to be a savvy consumer! In the end, we become members of the faithful for this brand or that. Faith should be a temporary condition in which we assume the goodwill of those we are investing our faux-trust in. Alas, humans have a terrible habit of staying too long in a condition of faith and often ignoring the evidence that suggests distrust might be a better attitude. I mean, why do people still vote Tory even as their lives are degraded year-on-year?

Cugel

[pwa]

Any tests done on smooth rollers rather than chip n seal mean absolutely nothing. If there is anyone out there testing these tyres with simulated chip n seal, great, but otherwise you just risk your money and hope for the best.

The only favourable thing I could say about that tyre without trying it would be that I have had good experiences with other Conti tyres in the past and would think it likely that these are also good.

[iandusud]

Nobody on here will pay that much for a tyre! I had 2 of the 4000s fail on the sidewalls, I'll stick to my Gatorskins at £23 from the wiggle thanks.

I've used GP4000s tyres exclusively on my road bikes for the last 5 years with no problems whatsoever. I ride all year round often on some rough tracks. I get about 5000 miles from a pr of tyres without having to replace them for cuts. Of course cuts can happen. I once fitted a new expensive tyre and got all of half mile before it was ruined by a piece of broken glass, but that's just bad luck. I've always paid less than £30 for a GP4000s. Based on my experience if I were to go over to tubeless I wouldn't hesitate to give the GP5000TL a go.

[Brucey]

the ethos of 'performance at any price' -which is the consumer version of the 'marginal gains' which has benefitted British Cycling in recent years- means that the 'rolling resistance' of tyres is an important factor in the buying decision. Of course folk will go to the few independent sources of test data and the website 'rolling resistance.com' is the first port of call.

They use a chequer-plate roller to do their tests. Better than a smooth roller in the way it represents a real road for sure, but any single surface cannot represent all real roads of course and this surface flexes the tyre in a characteristic way.

So tyre manufacturers who want to sell performance tyres (at a premium * ) will inevitably make sure that their tyres perform well on that particular roller test, whether that does or does not actually result in a faster tyre in the real world. The latter is something we will probably never know, because such testing is very difficult to do well; it is after all why a chequer plate roller is used in the first place. But yes some tyres do feel better than their roller results suggest and some worse. [A simple addition to the test would be to measure vibration transmitted into the wheel assembly; this would give some indication of comfort/ride quality at any given pressure; this could let you run higher pressures and still obtain good comfort/low suspension losses which may not be well captured by any roller test. Better yet might be to couple the test weight to the wheel assy using a compliant coupling of some kind so that suspension losses can be captured, but such a test would be 'gamed' by a better understanding of exactly how energy is absorbed in the compliant coupling.... ]

(*) There is good money to be made here; folk will pay about £50 each for tyres that are purportedly very fast and tough enough to survive real roads too. Expensive tyres don't normally cost x3 to make vs training tyres, so there is potentially a very healthy profit to be had.

That the GP5000TL has a 3/180 carcass surprised me. But it is a tubeless tyre, and it weighs about +80g more than the equivalent non-tubeless model. Continental are late to the tubeless party and the last thing they wanted to do was to screw up; some of the extra weight comes from the rubber in the sidewall meant to make it airtight, and some presumably comes from a stiffer, stronger bead reinforcement. [Tubeless tyres rely more heavily than tubed tyres on the strength and stiffness of the bead reinforcement, because the rim hooks are abbreviated and cannot be relied upon in a tubeless tyre anyway.]

There is a fundamental difference in a tubeless tyre; to hold air it must have rubber in the sidewall. Normally adding more rubber to a tyre sidewall just makes a tyre slower; it is therefore a question of adding the rubber in a way that results in the least rolling resistance whilst still keeping the air in. This probably means the most elastic (low hysteresis) rubber, that sees the least strain. Possibly the sealing rubber is more easily incorporated within/bonded to a 3/180 carcass than the 3/330 one. If so, in the latter case that rubber would be a relatively thick layer on the inside of the carcass whereas in the former case the rubber could be better incorporated within the structure of the carcass. This could be important in that the mean strain the sealing layer (when the tyre is flexed) would be reduced in the latter case and this might give a lower Crr measurement. [If you think of (say) a 1mm thick layer of rubber that is constrained to zero in-plane stress on one surface when flexed, it might see (say) 10% strain on the other face when the structure is flexed in bending. If instead there is 0.5mm of rubber each side of a centre plane that is roughly inextensible, the strain at the surface is only 5% instead. The energy stored goes as the area beneath a strain plot, so in the latter case it ought to be half as much; this effect could be dominant over other factors that determine the measured Crr value.]

So anyway, yes, any single test can be 'gamed' and this may be a case in point. But it is the best test we have for now and in truth any tyre that scores reasonably well on roller tests can be a pretty fast tyre in the real world too; the 'real' rolling resistance (including suspension losses etc) will vary with the road surface and lots of other things (even how tightly you hold the handlebars..) so we are never going to get a lab test that is 100% 'real' or that represents every rider.

cheers

[Canuk]

I'm also a long term user of the GP4000's. Same experience as a above : long life , good puncture resistance and fast rolling. All things being equal it was fun to roll away from my friends on long descents on similar wheels frames. I think the 5000's can only be an advantage.

Continental have been getting my money for nigh on 15 years, they're virtually standard on all my bikes and I much prefer them to Schwalbe or Michelin (which I used previously). The GP5000s should be keenly priced if the the 4000's are anything to go by. Excellent value for money.

[foxyrider]

Nobody on here will pay that much for a tyre! I had 2 of the 4000s fail on the sidewalls, I'll stick to my Gatorskins at £23 from the wiggle thanks.

Who says they won't? (my last few 4000s2's only cost £25 each)

I've never had a 4000 fail but I have had Gatorskins destroy themselves. But that means nothing - I used to get through Wobbler Juniors at an alarming rate and i've had Marathons fail long before they were worn out.

My sportive bike is due new tyres for 2019, they will almost certainly be 5000's. How much I actually pay for them is another matter.

[NATURAL ANKLING]

Hi,
So how many will be running the tyre at 120 psi?

[Samuel D]

Any tests done on smooth rollers rather than chip n seal mean absolutely nothing.

Disagree on two counts: that they mean nothing and that if the rollers were rougher they’d mean more. Smooth rollers of whatever size give an indication of energy losses to hysteresis in the flexing tyre that closely correlates to its strict rolling resistance. Making the roller rougher does not mean the machine will vibrate with damping losses representative of a human body. For this reason I don’t even see much point in the diamond plate that Bicycle Rolling Resistance uses.

I agree with you and Brucey that it’s complex and that no test can fully predict real-world performance.

But if performance on a particular test becomes important to market success, gaming the test is a near-inevitable outcome. The Volkswagen diesel emissions scandal showed us that. The 5000 TL’s stiff sidewalls make me think we’re witnessing that now, maybe for the first explicit time. (Using low-hysteresis tread compound has been done before, but that is slightly different because it does deliver the implied performance, albeit at a cost of wet grip.)

I’m interested to hear people’s experiences with these new tyres. Has anyone come across comments by Tom Anhalt, by the way? There’s nothing on his Twitter account or Blather 'bout Bikes blog.

[Dafydd17]

I mean, why do people still vote Tory even as their lives are degraded year-on-year?

Probably because, until fairly recently, the choice was between a real right-wing party and a wannabe plastic-imitation right-wing party?

(Sorry, nothing to do with the topic...
I'll get me coat)

[foxyrider]

Hi,
So how many will be running the tyre at 120 psi?

I'm no longer weighty enough to need that

[Samuel D]

So how many will be running the tyre at 120 psi?

What is implied by this question?

[The utility cyclist]

Any tests done on smooth rollers rather than chip n seal mean absolutely nothing. If there is anyone out there testing these tyres with simulated chip n seal, great, but otherwise you just risk your money and hope for the best.

The only favourable thing I could say about that tyre without trying it would be that I have had good experiences with other Conti tyres in the past and would think it likely that these are also good.

Having looked at the drum used by Bicyclerollingresistance i'd say it offered up a consistently rough surface, one that I would not experience all the time, even on urban roads. In any case surely it's a comparison using the same set of parameters that are more important no?
Also, some wider tyres will only have a lower Crr than some narrower tyres (note some not all) IF they are pumped up to a level that would supposedly sacrifice comfort, thus making the claim a wider tyre is faster a complete nonsense for real world use.
Sure if you ride on permanently rutted road for most of your journey things may be different but given the testing is not done on a smooth surface there is at least a nod to the everyday roads.

As for the claim that the TL will still be faster than tubed variant with a latex tube, sorry, I don't believe it, in any case the tester on BRR only uses 20ml of sealant, how many riders use that little in real world use, particularly when we know that losing some/evaporation is a real thing and the big upside is to prevent deflation from a puncture.
When the gains are so small, that extra 10ml or so rolling around is enough to change matters.

I'll be sticking to my tubs for when speed is the main priority, I'm sure for some TL works but there's no standardisation and the stiffer sidewalls of TL tyres is going to have a negative effect in ride quality. Also given the lower max pressures this is very limiting for bigger riders/loaded touring unless you use very wide tyres which isn't for everyone.
Clinchers for me, it also means not having to buy different wheels and the hassle/difficulty of getting tyres back on at the side of the road, no thanks!

[NATURAL ANKLING]

Hi,
Well I was just curious as the fashionable thing today is to run tyres at lower pressures which will also affect cr?
Though compared with the completion available my question becomes sort of moot as running the top five tyres at any useable pressure does not change their positions relative to each other.
Personally I am not in favour of running tyres soft to gain comfort.