If you don’t want to get into the details, here’s my bottom line. For the best combination of minimum rolling resistance, maximum aerodynamic performance and confident handling, order a pair of Continental Grand Prix 4000S II clincher tires online at eBay Cycling, Wiggle, ProBikeKit, Merlin or Chain Reaction in the 23C/23mm size and pump them up to between 95psi/6.5bar (lighter riders, softer ride) and 115psi/8bar (heavier riders, firmer ride) and use a light butyl inner tube. Don’t use a 25C/25mm size Conti tire unless you have wheels that are 27mm or wider at the brake track and don’t buy them in a physical store where they will cost you at least 2/3rds more.
I’m most surprised with the flat test. In my experience, the Vittoria Corsa CX tires are nowhere near as flat resistant as the GP4000s or Rubino Pros. Maybe the CX III has an extra puncture belt?
Look back at how the flat test was conducted, it’s not really very consistent with daily riding. It was basically a measure of how much force it took a 1mm needle to puncture the tire… not very useful information in my opinion, unless you ride on needles often.
I’m most surprised with the flat test. In my experience, the Vittoria Corsa CX tires are nowhere near as flat resistant as the GP4000s or Rubino Pros. Maybe the CX III has an extra puncture belt?
No, they still suck. None of the “open tubular” racing tires are good with glass IME. Not nearly as good as Conti. Wires and staples and thorns are best dealt with using latex tubes, since they seem to puncture any tire. The latex is stretchy enough to conform around it without puncturing, so long as you pull the object out asap.
I don’t know how he can advocate not using latex tubes because they’re fragile and at the same time advocate the use of light butyl tubes.
Yes, now that I think about it, there was a lot of stuff he got wrong, but I was more impressed with the wealth of info in one spot and what he got right! And the stuff he got wrong wasn’t totally stupid. He was probably going by the plethora of negative reviews on latex because few people know how to properly install a tube.
If the GP4000S is the no-brainer catch-all racing tire, what is a comparable training tire?
Cost is not an issue, just durability, but I’m not sure I want to give up too much CRR by opting for a full-on bullet proof “off-season” tire like Gatorskins.
Would you recommend a different tire for training / long group rides? Or just ride the GP4000S?
We do end up on some sketchy rutted-out / gravelly roads sometimes.
I use Gatorskins in the winter/spring when the roads are bad (I live in pothole land) and its often cold enough to make changing a flat an unpleasant experience so extra flat protection is a plus. A lot of my riding companions have moved to Gatorskins too over the past few years at least for the “off” season. I train the rest of the year on 4000s and race on them too. I find the 4000s to be very good at avoiding punctures but the Gatorskins are better at avoiding sidewall cuts and pinch flats on super rough roads. The Gatorskins are a little bit better on punctures but frankly the 4000s are pretty bullet proof themselves on that front as long as you don’t hit something bad.
As for the watt difference, I’ve never measured it but the 8.7 watts sounds right. It is definitely a noticeably better ride on the 4000s vs Gatorskins.
If the GP4000S is the no-brainer catch-all racing tire, what is a comparable training tire?
Did he say it was? I thought he said it was a catch-all for everything? IMO the GP4000 is a training tire, and it’s really too harsh riding now that all the roads have been chipsealed. But I still use it on the rear, because all the smoother and lower Crr tires get cuts. Except for the Attack and Force which are the same in construction except they have thinner tread.
If you need greater durability I think you have to go to something like a Gatorskin… and get an even harsher ride, and much higher Crr.
For racing there are faster tires, at least in Crr but aero is tougher to nail down. Attack and/or Force are good options. If you aren’t overly concerned about flats, there are the Supersonics, and Vittoria and Specialized “open tubulars”.
Note that rolling resistance wattage is linear with the rider’s weight. It looks like his “standard wattage” uses a 42.5kg rider, if you click through to a review. So if you’re like me and weigh twice that, then you can double all the wattage numbers (which means gatorskins double their gap to the best tire).
Note that rolling resistance wattage is linear with the rider’s weight. It looks like his “standard wattage” uses a 42.5kg rider, if you click through to a review. So if you’re like me and weigh twice that, then you can double all the wattage numbers (which means gatorskins double their gap to the best tire).
42.5kg is the test load. His GP4000S numbers are essentially the same as Tom A.'s numbers (which are based on total system weight of 85kg) so I’m pretty sure he adjusted to a reasonable rider+bike weight.
However, 8.7W is at 18mph so you are looking at potentially a 15-50%+ bigger gap at average triathlon speeds.
Ok, fair enough. Thanks for the feedback. I’ve ordered a few sets of the GP4000S for training. I do have a Vittoria on my Zipp 900, but have pretty much just used Bontrager tires on my Aeolus wheels for years (for both training and racing). Flats have never really been a concern, but maybe I’ve been giving up some Crr. Also have latex tubes, so may just put a Vittoria on the 9.0 front and call it good for now.
I don’t know how he can advocate not using latex tubes because they’re fragile and at the same time advocate the use of light butyl tubes.
Yes, now that I think about it, there was a lot of stuff he got wrong, but I was more impressed with the wealth of info in one spot and what he got right! And the stuff he got wrong wasn’t totally stupid. He was probably going by the plethora of negative reviews on latex because few people know how to properly install a tube.
It’s a good start, especially for “traditionalist” cyclists. Not really a fan of his writing style or a lot of the content though.
Note that rolling resistance wattage is linear with the rider’s weight. It looks like his “standard wattage” uses a 42.5kg rider, if you click through to a review. So if you’re like me and weigh twice that, then you can double all the wattage numbers (which means gatorskins double their gap to the best tire).
42.5kg is the test load. His GP4000S numbers are essentially the same as Tom A.'s numbers (which are based on total system weight of 85kg) so I’m pretty sure he adjusted to a reasonable rider+bike weight.
However, 8.7W is at 18mph so you are looking at potentially a 15-50%+ bigger gap at average triathlon speeds.
Rolling resistance power loss is a fairly straightforward equation:
Power = SpeedInM/S * 9.81 * Mass * Crr
His GP4000S Crr @ 100psi is 0.00333
Power = 8.059.8142.5*0.00333 = 11.1W, which exactly matches his wattage number. This confirms that his wattage numbers are derived from a 42.5kg rider.
Therefore, if we double the weight, we double the power lost. You have a good point about speeds too: Upping the speeds will up rolling resistance losses linearly as well.
For an 80kg someone doing 40km/h:
Gatorskin = 11.19.81800.00606 = 52.7W
GP4000S = 11.19.81800.00333 = 29.0W
So instead of the apparent 8.7W difference listed for 42.5kg/29km/h, there’s a 23.7W difference at the higher weight and speed.
It’s kinda weird really that he posts wattages, since they’re such an individual thing in the real world. Crr is really all that matters. Wattage helps you “visualize” how much you’re losing, but since it is dependent on your average speed and weight, all his wattage numbers will just be the Crrs multiplied by some constant. It’s best to calculate the wattage loss based on your own situation.
Rolling resistance power loss is a fairly straightforward equation:
Power = SpeedInM/S * 9.81 * Mass * Crr
His GP4000S Crr @ 100psi is 0.00333
Power = 8.059.8142.5*0.00333 = 11.1W, which exactly matches his wattage number. This confirms that his wattage numbers are derived from a 42.5kg rider.
Bike has two wheels, so a load of 42.5kg on a wheel is representative of a 85kg rider (in reality, weight distribution isn’t 50/50 and varies with position).
Therefore, if we double the weight, we double the power lost. You have a good point about speeds too: Upping the speeds will up rolling resistance losses linearly as well.
For an 80kg someone doing 40km/h:
Gatorskin = 11.19.81800.00606 = 52.7W
GP4000S = 11.19.81800.00333 = 29.0W
So instead of the apparent 8.7W difference listed for 42.5kg/29km/h, there’s a 23.7W difference at the higher weight and speed.
It’s kinda weird really that he posts wattages, since they’re such an individual thing in the real world. Crr is really all that matters. Wattage helps you “visualize” how much you’re losing, but since it is dependent on your average speed and weight, all his wattage numbers will just be the Crrs multiplied by some constant. It’s best to calculate the wattage loss based on your own situation.
You ultimately care about a reduction in power needed (watts). Crr is the most accurate metric but it’s not readily converted to watts. Since rolling resistance is linear, it’s not too hard to adjust for different combinations of speed and weight. I think the main problem here is he didn’t quote the assumed rider weight in all the tables.
Bike has two wheels, so a load of 42.5kg on a wheel is representative of a 85kg rider (in reality, weight distribution isn’t 50/50 and varies with position).
This is true, but it still means his tables might be misleading for someone that didn’t think of that (and I didn’t). They aren’t labelled as “per wheel”, and in any case it’s still dependent on the rider. Which goes back to my original post, highlighting that people should make sure to consider the weight on their tires and to not just blindly use the wattage numbers in the table. A naive reading might make you think “ooo, a gatorskin is only 8.7W worse”, when in fact for the average person and triathlete speed it is much worse than that.
You ultimately care about a reduction in power needed (watts). Crr is the most accurate metric but it’s not readily converted to watts. Since rolling resistance is linear, it’s not too hard to adjust for different combinations of speed and weight. I think the main problem here is he didn’t quote the assumed rider weight in all the tables.
You do ultimately care about watts, but the only parameter that different tires will give you is an improved Crr*. And if you’re going into such detail to figure out pure wattages gained/lost (since you might be cross-comparing to see which tires work best aerodynamically with your wheels), you shouldn’t be using wattages out of this guy’s tables, you should be computing the rolling wattage and aero wattage yourself from the Cda/Crr data you’re using and your own known weight.
*And a varying amount of flatting risk, but if you’re buying race tires, you’re presumably ignoring that.
It’s kinda weird really that he posts wattages, since they’re such an individual thing in the real world. Crr is really all that matters. Wattage helps you “visualize” how much you’re losing, but since it is dependent on your average speed and weight, all his wattage numbers will just be the Crrs multiplied by some constant. It’s best to calculate the wattage loss based on your own situation.
