New Continental 5000S Tires - Tubeless Compatible
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The spirit of this board is to compile and organize wheels and tires related discussions.
If a new wheel tech is released, (say for example, TPU tubes, a brand new tire, or a new rim standard), feel free to start the discussion in the popular "Road". Your topic will eventually be moved here!
The spirit of this board is to compile and organize wheels and tires related discussions.
If a new wheel tech is released, (say for example, TPU tubes, a brand new tire, or a new rim standard), feel free to start the discussion in the popular "Road". Your topic will eventually be moved here!
^ I 'd find that surprising. RR is based mostly on hysterisis. Less rubber on the tread means less hysterisis. Apparently this is what happens to race car tires - as they wear, the tread gets thinner, builds less heat, and the compound falls out of its operating range. Drivers end up overdriving the tire, sliding it, and then overheating it.
However, as a bike tire gets more worn and becomes squared off, aero becomes worse, so overall, the tire might get slower.
However, as a bike tire gets more worn and becomes squared off, aero becomes worse, so overall, the tire might get slower.
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Alright, this post piqued my curiosity, so I tried to mount some 25mm GP5K TLs to my 5.6s (19mm internal.)
I can confirm MXGimp's claims. I've never had so much trouble mounting any clinchers, tubeless or not. I could barely get them on with levers and I was afraid of snapping them in half the whole time. It was tough even getting the first bead over the rim, let alone the second. I had to firmly hold the last portion of the second bead in place while pulling the lever a couple centimeters at a time.
This is a total buzzkill and I'm pretty sure I will just be sticking with Hutchinson Fusions or trying the Vittoria Corsa G+ TLR when they are available. The rolling efficiency gains aren't worth this amount of trouble IMO.
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With the beads that tight, does it require just a floor pump to seat?
Rikulau V9 DB Custom < BMC TM02 < Litespeed T1sl Disc < Giant Propel Advanced SL Disc 1 < Propel Adv < TCR Adv SL Disc < KTM Revelator Sky < CAAD 12 Disc < Domane S Disc < Alize < CAAD 10
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Tight beads are generally worse for seating than looser ones because friction is the enemy. That's why people use lubes or soapy water. Anyway the bead kind of partially seated with just a floor pump, but it was leaking air all over, so I sloshed around some sealant and the rest of the bead snapped into place.
Someone else I know reports they are easier to mount than Vittoria Corsa Speed TLR, but he is using Mavic UST rims, which are known to be spot on with ETRTO standards. I'm guessing my ENVEs are a bit larger diameter in addition to being wider, and the GP5K TL are most definitely smaller than ETRTO standard.
Forgot to mention the 25mm tires also inflated to a pre-stretch width of 26.3mm on the 19mm 5.6s at 100psi, so they are very narrow indeed. I see that Jarno measured his sample at 26.8mm on 17mm rims...so we'll see how much they stretch over the next couple days.
If enough people return the TL tires then perhaps that will make Conti take notice. This issue doesn't affect me directly as I don't run TL on my road bikes. But a tight tire is the #1 reason for me not going TL at this point. I ride in the cold and I just cannot remove a tire to put in a tube if that's the only way I can finish the ride. I have a hard time as is to remove a loose tire in the cold without gloves.
Eugene,
I wonder if a different tire size will make a difference. Just a thought. It wouldn't hurt to try the GP5K 28mm if you can get a refund on the 25s. The GP5K 28s are only very slightly wider than the old GP4K 25s.
Yeah, there's a 0.5mm stretch with mine after a few hours. I'm surprised that the 25s are just a tad narrower than my 28s at 27.5mm. Maybe I got an unusual sample on my 28s? You would think there would be a 3mm differnce but it's only 1mm different. I take five or six width measurements and average them. The tire is not uniformly wide at every point.
I wonder if a different tire size will make a difference. Just a thought. It wouldn't hurt to try the GP5K 28mm if you can get a refund on the 25s. The GP5K 28s are only very slightly wider than the old GP4K 25s.
Yeah, there's a 0.5mm stretch with mine after a few hours. I'm surprised that the 25s are just a tad narrower than my 28s at 27.5mm. Maybe I got an unusual sample on my 28s? You would think there would be a 3mm differnce but it's only 1mm different. I take five or six width measurements and average them. The tire is not uniformly wide at every point.
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The second tire mounted slightly easier, but still pretty difficult.
pdlpsher1, the regular clinchers come up narrower. Jarno's clincher 25mm measured 26.2mm on a 17mm rim. I asked about 32mm availability and was quoted March/April. I figure 28mm availability is in the same timeframe.
pdlpsher1, the regular clinchers come up narrower. Jarno's clincher 25mm measured 26.2mm on a 17mm rim. I asked about 32mm availability and was quoted March/April. I figure 28mm availability is in the same timeframe.
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Can't you just dry mount them with a tube on an oldschool clincher like an Open Pro to stretch for a bit?
I have to disagree, in my experience tighter fits trap air and are the only way to get a tyre up with a track pump, otherwise I have to use the AirShot.
I know that for riding in the big mountains I much prefer a tight tyre, I've no idea how I used to feel safe on loose fitting clinchers that would be guaranteed to unseat if you lost pressure.
I have to disagree, in my experience tighter fits trap air and are the only way to get a tyre up with a track pump, otherwise I have to use the AirShot.
I know that for riding in the big mountains I much prefer a tight tyre, I've no idea how I used to feel safe on loose fitting clinchers that would be guaranteed to unseat if you lost pressure.
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You can disagree all you want, but even the loosest UST tires like Mavic Yksion Pros are “air tight” when sitting in the center channel. Friction is the main issue forcing people to use compressors and CO2. Beads popping out when deflated is more of a problem associated with poorly designed rims rather than “loose” tires. My Hutchinson Fusions and Mavic Yksion Pros are some of the “loosest” tires around and they stay seated at 0 psi on all of my tubeless-ready wheels (ENVE, Zipp, Ultegra, Alto, Velocity Aileron, etc.)
It’s also one of the specific claims made by Mavic about UST. Their tires only need a floor pump because they haven’t cheated like other manufacturers who make larger circumference rims or smaller circumference tires.
It’s also one of the specific claims made by Mavic about UST. Their tires only need a floor pump because they haven’t cheated like other manufacturers who make larger circumference rims or smaller circumference tires.
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Yikes. I’ve had trouble mounting my Yksion UST on Mavics. Could be I just got a slightly out of spec larger wheel, but that makes me quite wary of the Continentals now.TobinHatesYou wrote: ↑Thu Jan 10, 2019 1:31 am
Alright, this post piqued my curiosity, so I tried to mount some 25mm GP5K TLs to my 5.6s (19mm internal.)
I can confirm MXGimp's claims. I've never had so much trouble mounting any clinchers, tubeless or not. I could barely get them on with levers and I was afraid of snapping them in half the whole time. It was tough even getting the first bead over the rim, let alone the second. I had to firmly hold the last portion of the second bead in place while pulling the lever a couple centimeters at a time.
This is a total buzzkill and I'm pretty sure I will just be sticking with Hutchinson Fusions or trying the Vittoria Corsa G+ TLR when they are available. The rolling efficiency gains aren't worth this amount of trouble IMO.
That is not true, as I don't think there is any standards for the center channel's shape or width to comply with. Therefore a combination of rim and tire may yield differing results than another combination.TobinHatesYou wrote:You can disagree all you want, but even the loosest UST tires like Mavic Yksion Pros are “air tight” when sitting in the center channel. Friction is the main issue forcing people to use compressors and CO2.
My usual procedure is: try with a compressor -> bead is not air tight against the channel, so no initial pressure is achieved and nothing productive happens -> remove valve core and try again -> air volume is adecuate to "push" the tire's sidewalls against the channel's edges -> initial pressure gathers -> air tightness is achieved -> pressure rises -> bead pops into place. Doesn't make much of a difference if the tire is new, or used but dry, or used but rinsed in sealant.
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The tire is effectively a stretched elastic band even when sitting in the center channel, so it is reasonably “air tight.” The air will find the path of least resistance in very tiny gaps when the friction force is stronger. Please think about why soapy water helps and products like Schwalbe Easy Fit exist. Do you think the soapy water is plugging the holes?.. No, it’s acting as a lubricant under the bead.
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Race car tires are similar yet different. The demands and priorities are different.spud wrote: ↑Wed Jan 09, 2019 5:56 pm^ I 'd find that surprising. RR is based mostly on hysterisis. Less rubber on the tread means less hysterisis. Apparently this is what happens to race car tires - as they wear, the tread gets thinner, builds less heat, and the compound falls out of its operating range. Drivers end up overdriving the tire, sliding it, and then overheating it.
However, as a bike tire gets more worn and becomes squared off, aero becomes worse, so overall, the tire might get slower.
Remember that most proper race cars have 3 stage independant suspensions to keep the wheels to the road.
Rolling resistance and hysterisis losses are a minor consideration. With race cars, GRIP is EVERYTHING ( for acceleration, braking and cornering, as race cars are almost always doing one of the three).
So with race cars the key is rubber compount, heat, and air pressure.
A cold race car tire’s rubber is soft. You can dig your fingernail i to it easily. A hot race car tire is sticky! That is increased rolling resistance... and given the importance of grip, that is a very good thing.
Tire pressures are also equally essential. You want the pressure that maxamizes the contact patch size, without being too soft that the tire flexes to the point of hurting the contact patch, or uneven tire wear. If the pressures are too high, the contact patch arches (you want a big flat contact patch) and you reduce contact area and grip.
The trick is, due to all the friction that the tires see, they generate a lot of heat quickly. Heat expands air and raises tire pressures. The more you work the tires (the faster you go), the hotter the tire. Lets say for a given car, 30psi is the optimal hot pressure. Cold, you might need to start with 20psi.
To a point, the hotter the tire, the more grip you get... and thus more heat is generated (as the tire gets more sticky as it reaches it’s optimal temperature range). This heat increases the tire psi further.
Eventually, if you overdrive the tires, and slide around too much, the rubber can get too hot, causing sticky to turn just greasy, and the air expanding further, rounding off the flat profile of the tire, reducing contact patch size... and further hurting grip.
So tire pressure choice is key, and not over-driving the tire is key. You also need a few laps to properly “warm up the tire” before you are at optimal speed.
It really is a balance. And depending on the track, different loads will be put on each tire, so often each tire will be set at a different “cold pressure” so that once hot, all 4 will be optimal.
The death of most (amateur) race tires is not wearing out the tread like road tires, but rather “heat cycling”. A given tire tread may be thick enough to last 2-3 races. The problem is that every time that soft rubber compound heats up and cools down, it gets harder (less grip). The stickier/higher grip the tire, the faster this happens. A lower grip, “poor mans” race tire may work ok till it wears to the metal Cords. That may be 2-5 races based on the car/track/tire. A hoosier slick for qualifying might be good for 2-3 laps, and then it is garbage... but in that period you will feel like a god!
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I'm super curious - how have you measured the grip on the Contis vs IRCs? I just put IRC RBCC Pros (bought from you) on my Venge. Subjectively, my gut is they have better wet weather grip than the Contis (4000sii), but not quite as good as teh Specialized SWorks Turbo Tubeless tires. But I'm super curious if you've measured this in any way?