You can read it here: https://www.bicyclerollingresistance.com/road-bike-reviews/continental-grand-prix-5000-2018
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Stumbled upon that last night. Hopefully he will get the GP 5000 TL data up soon as well. AeroCoach also published some data here and included the 5000 (23 & 25), TL (25), 4000, and TT
Stumbled upon that last night. Hopefully he will get the GP 5000 TL data up soon as well. AeroCoach also published some data here and included the 5000 (23 & 25), TL (25), 4000, and TT
Hmmm…the aerocoach data shows the 23C versions of the GP5K vs. GP4K2 to be ~13% faster…which matches what Conti said…while the 25C GP5K is 20% faster than the 23C GP4K. Since all are tested at 90 psi, that makes sense. BTW, I calculate that if the 23C is tested at 90 psi, then the 25C tires should be inflated to 80 psi for an “apples to apples” comparison. The 18% better rolling for the 25C version comparison (GP5K vs. GP4K2) as reported by BRR seems a bit “off”…
Of course, the same is true with the BRR data in regards to pressure. His ranking is all with tires inflated to 120 psi regardless of size. To be fair, that’s how my own testing is reported, but I’m about ready to “freeze” that data set and start reporting only with the tires inflated to the “Berto 15% Drop” calculated pressure based on actual measured width.
I have a hard time believing the GP5K would be faster rolling than a Turbo Cotton…
On my Christmas list. I absolutely love my GP4K2 25 tires on my road bike. But they are a little long in the tooth now. Time for an upgrade.
Stumbled upon that last night. Hopefully he will get the GP 5000 TL data up soon as well. AeroCoach also published some data here and included the 5000 (23 & 25), TL (25), 4000, and TT
Hmmm…the aerocoach data shows the 23C versions of the GP5K vs. GP4K2 to be ~13% faster…which matches what Conti said…while the 25C GP5K is 20% faster than the 23C GP4K. Since all are tested at 90 psi, that makes sense. BTW, I calculate that if the 23C is tested at 90 psi, then the 25C tires should be inflated to 80 psi for an “apples to apples” comparison. The 18% better rolling for the 25C version comparison (GP5K vs. GP4K2) as reported by BRR seems a bit “off”…
Of course, the same is true with the BRR data in regards to pressure. His ranking is all with tires inflated to 120 psi regardless of size. To be fair, that’s how my own testing is reported, but I’m about ready to “freeze” that data set and start reporting only with the tires inflated to the “Berto 15% Drop” calculated pressure based on actual measured width.
I have a hard time believing the GP5K would be faster rolling than a Turbo Cotton…
This is what I love about you Tom. Hopefully BRR and Aerocoach choose the method they do for simplicity only and not just because they lack that thought. Aero testing should also be done with proper PSI and scale it appropriately.
Wow, and that test is with a butyl tube. Swap for latex and it might be in Corsa Speed territory
Stumbled upon that last night. Hopefully he will get the GP 5000 TL data up soon as well. AeroCoach also published some data here and included the 5000 (23 & 25), TL (25), 4000, and TT
Hmmm…the aerocoach data shows the 23C versions of the GP5K vs. GP4K2 to be ~13% faster…which matches what Conti said…while the 25C GP5K is 20% faster than the 23C GP4K. Since all are tested at 90 psi, that makes sense. BTW, I calculate that if the 23C is tested at 90 psi, then the 25C tires should be inflated to 80 psi for an “apples to apples” comparison. The 18% better rolling for the 25C version comparison (GP5K vs. GP4K2) as reported by BRR seems a bit “off”…
Of course, the same is true with the BRR data in regards to pressure. His ranking is all with tires inflated to 120 psi regardless of size. To be fair, that’s how my own testing is reported, but I’m about ready to “freeze” that data set and start reporting only with the tires inflated to the “Berto 15% Drop” calculated pressure based on actual measured width.
I have a hard time believing the GP5K would be faster rolling than a Turbo Cotton…
I look forward to the drop data. As an aside, I recently made a copy of your CRR spreadsheet and I’ve been working away at a “revised” version with estimates that normalize around size/pressure/casing tension. It’s imperfect but, as you’d expect, wider tires become slower and narrower tires become faster. I’ll be curious to see how my estimates correspond to your “15% drop” data.
Re TC: compound improvements are a beautiful thing 
I want to believe…
Wow, and that test is with a butyl tube. Swap for latex and it might be in Corsa Speed territory
Exactly IMO, it’s a pretty safe bet that the GP5000 is a more aero tire too so on combined aero/crr it appears to be the new king of the hill.
This is what I love about you Tom. Hopefully BRR and Aerocoach choose the method they do for simplicity only and not just because they lack that thought. Aero testing should also be done with proper PSI and scale it appropriately.
Alas, I strongly suspect the whole “wider is faster” marketing machine is based on an incorrect understanding of CRR. Most of the tests that have filled the pages of BikeRadar, BikeRumor, etc. have shown wider tires tested at the same air pressure as their narrower brethren. Amazingly, the reviewers then often go on to say that the wider tires felt “more supple.”
Wow, and that test is with a butyl tube. Swap for latex and it might be in Corsa Speed territory
Exactly IMO, it’s a pretty safe bet that the GP5000 is a more aero tire too so on combined aero/crr it appears to be the new king of the hill.
I’m not buying that result…yet…seems to be a bit of an “outlier”, even as compared to Conti’s claims.
Wow, and that test is with a butyl tube. Swap for latex and it might be in Corsa Speed territory
The corsa speed test on the BRR website is a 23mm. The TT and new GP5k is a 25mm on the site. If you adjust for casing tension, the gap between the GP5k and CS is larger than what is shown on the BRR site. A latex tube is going to help it but I wouldn’t call it CS territory.
Stumbled upon that last night. Hopefully he will get the GP 5000 TL data up soon as well. AeroCoach also published some data here and included the 5000 (23 & 25), TL (25), 4000, and TT
Hmmm…the aerocoach data shows the 23C versions of the GP5K vs. GP4K2 to be ~13% faster…which matches what Conti said…while the 25C GP5K is 20% faster than the 23C GP4K. Since all are tested at 90 psi, that makes sense. BTW, I calculate that if the 23C is tested at 90 psi, then the 25C tires should be inflated to 80 psi for an “apples to apples” comparison. The 18% better rolling for the 25C version comparison (GP5K vs. GP4K2) as reported by BRR seems a bit “off”…
Of course, the same is true with the BRR data in regards to pressure. His ranking is all with tires inflated to 120 psi regardless of size. To be fair, that’s how my own testing is reported, but I’m about ready to “freeze” that data set and start reporting only with the tires inflated to the “Berto 15% Drop” calculated pressure based on actual measured width.
I have a hard time believing the GP5K would be faster rolling than a Turbo Cotton…
I think that would be a great idea. It would make it easier for us nerds to see which tyre is fastest and make it educational for the more novice users
As an aside, am I the only one that would love to see sub-23mm tubeless tyres? Perhaps the biggest benefit with tubeless for me would be the increased pinch flat protection, but I’m not willing to run 27+mm tyres (especially on the front - and yes, a stated 23mm tyre measures 27+mm on my Jet 9 Black rim). A narrower tubeless tyre would help with one of the qualms of running narrower tyres, i.e. pinch flats. Not holding my breath any manufacturer is coming out with one, though.
not to mention a CS with a latex tube would be faster still… unless they tested it with a latex for some reason
not to mention a CS with a latex tube would be faster still… unless they tested it with a latex for some reason
He (Jarno at BRR) actually tested it set up tubeless (with sealant)…so, basically the same as if it had a latex tube inside.
BTW, I calculate that if the 23C is tested at 90 psi, then the 25C tires should be inflated to 80 psi for an “apples to apples” comparison.
I’m not so sure. People do generally run lower pressure with wider tires, but that isn’t because they need to. It’s because they value comfort. And on a real road they might be at the part of the curve where the low pressure is actually better (lower Crr)… as opposed to the roller where Crr always drops as pressure increases. I can see it either way, but I think using the same pressure for all tires is better for roller testing. The Crr improvement is a real advantage of bigger tires. The spring rate of the tire is controlled by pressure also, so you are normalizing that aspect by running them all at the same PSI.
I’ll probably pick up a pair to race with next year and see how it goes. I still have a pretty large stock of GP4000S2’s that I’ll train on given the slightly better puncture protection.
I figured it was too good to be true to claim lower weight, better CRR, and better puncture resistance. But overall looks like a good tire.
Alas, I strongly suspect the whole “wider is faster” marketing machine is based on an incorrect understanding of CRR.
Only because they are ignoring aero. Wide tires really do have better Crr.
I’ll illustrate why I think roller testing at the same psi makes more sense. Say you have 20mm, 23mm, and 25mm models of the same tire. At the same psi they will all have the same spring rate. This is from both Damon Rinard and Josh Poertner. So the ride compliance will be about the same. If that is your normalizing factor, then the wide tire is better for Crr. The wider tire gives you additional advantages if the road is rough or you are in danger of potholes or rocks that could result in a pinch flat. In addition you can run the wide tire at lower PSI, if you desire more ride compliance, or the road is so rough that lower psi is a Crr benefit. With small tires you don’t have that option.
Testing at different pressures on the rollers is a poor comparison IMO.
BTW, I calculate that if the 23C is tested at 90 psi, then the 25C tires should be inflated to 80 psi for an “apples to apples” comparison.
I’m not so sure. People do generally run lower pressure with wider tires, but that isn’t because they need to. It’s because they value comfort. And on a real road they might be at the part of the curve where the low pressure is actually better (lower Crr)… as opposed to the roller where Crr always drops as pressure increases. I can see it either way, but I think using the same pressure for all tires is better for roller testing. The Crr improvement is a real advantage of bigger tires. The spring rate of the tire is controlled by pressure also, so you are normalizing that aspect by running them all at the same PSI.
The spring rate of the tire is determined by BOTH the air pressure AND the casing tension. For a given pressure, increasing tire width increases the casing tension portion. Normalizing for casing tension is a better approach IMHO (in both testing and “real life”)…a wider tire ridden at the same pressure as a narrower tire will have a higher “spring rate”. IIRC, Damon’s tire deflection data showed that.
The spring rate of the tire is determined by BOTH the air pressure AND the casing tension. For a given pressure, increasing tire width increases the casing tension portion. Normalizing for casing tension is a better approach IMHO (in both testing and “real life”)…a wider tire ridden at the same pressure as a narrower tire will have a higher “spring rate”. IIRC, Damon’s tire deflection data showed that.
I’m out the door now, but I’m pretty certain that both of those guys reported that the spring rate was a very close function of pressure only and size independent… same tire model of course.