Since June 30th this year, I've been using the Continental Grand Prix 5000S TR tubeless on my rear wheel (→here)
First, here's a photo from when it was new, linked from my earlier post.
The discontinued original tubeless tire, the Grand Prix 5000 TL, is different from the clincher version Grand Prix 5000 in that threads don't come out of the bead area. But with the 5000 TL, it seems to use the same construction method as the Grand Prix 4000, so threads started coming out of the bead area with age and use.
↑With the Grand Prix 4000 series, when threads come out, it looks like this
I wanted to monitor this carefully so I could say definitively how the 5000S TR handles this, which was partly why I switched to this tire. And I can confirm that the Grand Prix 5000S TR does not have threads coming out of the bead.
These threads somehow end up wrapping around the rear derailleur pulley area, but the worst case I've seen is when they got tangled around the freewheel body pawls (→here).
Until now, knowing that tire life was short, I was using the IRC lightweight tubeless-ready tire Formula Pro S-Lite. When I first started using the Grand Prix 5000S TR, my impression was "the contact patch feels like it's really kicking the ground, but there's a kind of dragging heaviness." Comparing that to the S-Lite, which can get the rotational mass of the drive wheel close to that of a TPU tube plus lightweight clincher tire, is a bit unfair. But still, the durability is on a completely different level from the S-Lite. As long as I don't get a sidewall cut or anything, at my usage frequency (though it hasn't happened yet), it's certain I can get more than six months out of it. With the S-Lite, I've had to replace it in as little as just over two months. Also, the tire definitely gets fatter. What was almost 25mm under operating pressure is now slightly over 26mm. The rim is a DT XR331, which compared to modern wide rims actually has a narrower internal width, so tires tend to run narrower on it. Well, maybe the fact that it gets fatter also relates to how much longer it lasts.
For the past three weeks or so, I've been commuting on my gravel bike and haven't ridden the bike with the Grand Prix 5000S TR at all. In that time, the pressure dropped to about 2 psi, and when I pushed with my finger, it collapsed like something soft. I pumped it back up to 7 psi from there, but after that it went flat in about half a day—not just 2 psi but completely flat, like a full puncture.
Thinking maybe I had punctured it, I looked around the entire tire and found one noticeable cutwhile hinting at my assembled gravel bike, which is shown in the photo above.
When I investigated, both the suspicious cut and the rest of the tire showed no actual puncture. So what's going on...?
I had a customer with a hookless rim wheelset (of course) running tubeless tires. They left it unused for about six months, and the air pressure dropped, losing the bead's seal to the rim. The bead lost its tension, internal air reached the inside of the tire, and at that contact point's phase, the sealant solidified like yuba (bean curd skin). That customer was using Caffo Latex sealant, but with Stans sealant it hardens like chewed gum and sticks really powerfully to the inside of the tire.
The XR331 isn't a hookless rim, but it has no humps (the protrusions that hold the bead) on the outer edge of the rim, so when pressure drops below a certain threshold, it can't maintain bead retention. This doesn't normally happen in three weeks, but when the pressure was down to about 2 psi and I added air, maybe I triggered some kind of state where "the wet sealant inside the rim would hold things fine at 2 psi and below, but can't handle too much higher pressure."
About the case I mentioned earlier where it was left for six months and the bead dropped and the sealant hardened—I found out after six months, but it probably happened three to four months in. The tire was a 28C road tire.
With cyclocross wheels left alone for more than six months during off-season, bead drop and sealant hardening from air exposure doesn't always happen. But I've had customers bring in cyclocross tires left unused all off-season where they said "there's something moving inside the tire." Looking at it, all the sealant had become one solid mass at the contact point when it was left, but that mass wasn't sticking to the tire—it had separated. So when you'd spin the wheel slowly, you'd hear it rustling inside as it moved toward the bottom, like a hamster wheel.
The sealant is dried at the contact point between bead and rim.
Sure enough, it had turned to yuba inside the rim. The sealant is Imajee, and this is the first time I've seen this sealant become something other than liquid inside a tire. The adhesion to the rim was extremely weak, so it was easy to peel off the tire.
Inside that problematic cut, but it wasn't puncturing through.
I mostly removed the hardened sealant. I put Imajee sealant back in the tire, pumped up the bead with pressurization to about 6 psi, left it for a day, and there was almost no pressure loss, so I decided to keep using the tire instead of replacing it.
Aged tubeless tires generally have more difficulty getting the bead to seat than new ones, and the Grand Prix 5000S TR was the same. I'm thinking I'll eventually go back to the days of burning through IRC S-Lite tires like crazy, but separately from that, I've already decided what tubeless tire I'll use next. I'll probably only use it once. I'll write about that when the time comes.
On a different note, I have a female customer who had four punctures on Continental Grand Prix 5000 Transparent 25C clinchers in two weeks. She said the tire might be defective, so I checked and found the cause was different in all four cases: loose valve core, puncture from outside, puncture from inside despite rim tape being fine, and unknown cause. The strange thing was—on the second or third puncture, she was riding a different bike (her usual commuter) than the one with the questionable tire, and yet the next day all the air was out. If a puncture happened the day after riding, you can't rule out hitting something the day before. But for air to go flat on a bike you're not riding but keeping an eye on—that's weird. It's not a slow leak either; it just goes completely flat suddenly when you check it. And come to think of it, one of the times it even punctured while sitting in her car. Considering all this, the only explanation is the existence of a supernatural being known as the "Puncture Mister." He must be sneaking into a solo-living customer's house or car with a mysterious spare key, puncturing her tires, then sneaking into her bedroom to lick her cheek while she sleeps, and putting his spit in the barley tea in her fridge before leaving. When I told her not to worry, it was just "Puncture Mister," she said "That's way too scary!"
Since she mentioned the tire might be the problem, and it was something we sold at the shop, I replaced it with a new one. After that, whether "Puncture Mister" found peace or whatever, the mysterious air loss incidents that had been happening frequently stopped. Since I wanted to prove that the original tire wasn't the cause, I drew something like a rabbit on the tire's sidewall with a permanent marker, then asked the customer to draw something next to it. What she drew next to my rabbit—that's where the title "Dora-Mine" comes from. I've been using the Dora-Mine tire ever since, and it still hasn't punctured.
August 10th
This is my first morning ride since putting on the Dora-Mine tire. The location is Oku-Mizuma.
I'm not using this saddle bag anymore.
This is
Dora-Mine!
August 27th, pretty much the same place.
November 7th. I'm riding at a time that crosses sunrise while out in the mountains, but
rain started falling. I didn't photograph it clearly, but this day too it's the Dora-Mine tire. I haven't changed it since putting it on the front wheel.
This is the condition as of today (December 6th). Still no punctures.
As for Dora-Mine's appearance, it looks familiar from somewhere, but don't think about it too hard.
First, here's a photo from when it was new, linked from my earlier post.
The discontinued original tubeless tire, the Grand Prix 5000 TL, is different from the clincher version Grand Prix 5000 in that threads don't come out of the bead area. But with the 5000 TL, it seems to use the same construction method as the Grand Prix 4000, so threads started coming out of the bead area with age and use.
↑With the Grand Prix 4000 series, when threads come out, it looks like this
I wanted to monitor this carefully so I could say definitively how the 5000S TR handles this, which was partly why I switched to this tire. And I can confirm that the Grand Prix 5000S TR does not have threads coming out of the bead.
These threads somehow end up wrapping around the rear derailleur pulley area, but the worst case I've seen is when they got tangled around the freewheel body pawls (→here).
Until now, knowing that tire life was short, I was using the IRC lightweight tubeless-ready tire Formula Pro S-Lite. When I first started using the Grand Prix 5000S TR, my impression was "the contact patch feels like it's really kicking the ground, but there's a kind of dragging heaviness." Comparing that to the S-Lite, which can get the rotational mass of the drive wheel close to that of a TPU tube plus lightweight clincher tire, is a bit unfair. But still, the durability is on a completely different level from the S-Lite. As long as I don't get a sidewall cut or anything, at my usage frequency (though it hasn't happened yet), it's certain I can get more than six months out of it. With the S-Lite, I've had to replace it in as little as just over two months. Also, the tire definitely gets fatter. What was almost 25mm under operating pressure is now slightly over 26mm. The rim is a DT XR331, which compared to modern wide rims actually has a narrower internal width, so tires tend to run narrower on it. Well, maybe the fact that it gets fatter also relates to how much longer it lasts.
For the past three weeks or so, I've been commuting on my gravel bike and haven't ridden the bike with the Grand Prix 5000S TR at all. In that time, the pressure dropped to about 2 psi, and when I pushed with my finger, it collapsed like something soft. I pumped it back up to 7 psi from there, but after that it went flat in about half a day—not just 2 psi but completely flat, like a full puncture.
Thinking maybe I had punctured it, I looked around the entire tire and found one noticeable cut
When I investigated, both the suspicious cut and the rest of the tire showed no actual puncture. So what's going on...?
I had a customer with a hookless rim wheelset (of course) running tubeless tires. They left it unused for about six months, and the air pressure dropped, losing the bead's seal to the rim. The bead lost its tension, internal air reached the inside of the tire, and at that contact point's phase, the sealant solidified like yuba (bean curd skin). That customer was using Caffo Latex sealant, but with Stans sealant it hardens like chewed gum and sticks really powerfully to the inside of the tire.
The XR331 isn't a hookless rim, but it has no humps (the protrusions that hold the bead) on the outer edge of the rim, so when pressure drops below a certain threshold, it can't maintain bead retention. This doesn't normally happen in three weeks, but when the pressure was down to about 2 psi and I added air, maybe I triggered some kind of state where "the wet sealant inside the rim would hold things fine at 2 psi and below, but can't handle too much higher pressure."
About the case I mentioned earlier where it was left for six months and the bead dropped and the sealant hardened—I found out after six months, but it probably happened three to four months in. The tire was a 28C road tire.
With cyclocross wheels left alone for more than six months during off-season, bead drop and sealant hardening from air exposure doesn't always happen. But I've had customers bring in cyclocross tires left unused all off-season where they said "there's something moving inside the tire." Looking at it, all the sealant had become one solid mass at the contact point when it was left, but that mass wasn't sticking to the tire—it had separated. So when you'd spin the wheel slowly, you'd hear it rustling inside as it moved toward the bottom, like a hamster wheel.
The sealant is dried at the contact point between bead and rim.
Sure enough, it had turned to yuba inside the rim. The sealant is Imajee, and this is the first time I've seen this sealant become something other than liquid inside a tire. The adhesion to the rim was extremely weak, so it was easy to peel off the tire.
Inside that problematic cut, but it wasn't puncturing through.
I mostly removed the hardened sealant. I put Imajee sealant back in the tire, pumped up the bead with pressurization to about 6 psi, left it for a day, and there was almost no pressure loss, so I decided to keep using the tire instead of replacing it.
Aged tubeless tires generally have more difficulty getting the bead to seat than new ones, and the Grand Prix 5000S TR was the same. I'm thinking I'll eventually go back to the days of burning through IRC S-Lite tires like crazy, but separately from that, I've already decided what tubeless tire I'll use next. I'll probably only use it once. I'll write about that when the time comes.
On a different note, I have a female customer who had four punctures on Continental Grand Prix 5000 Transparent 25C clinchers in two weeks. She said the tire might be defective, so I checked and found the cause was different in all four cases: loose valve core, puncture from outside, puncture from inside despite rim tape being fine, and unknown cause. The strange thing was—on the second or third puncture, she was riding a different bike (her usual commuter) than the one with the questionable tire, and yet the next day all the air was out. If a puncture happened the day after riding, you can't rule out hitting something the day before. But for air to go flat on a bike you're not riding but keeping an eye on—that's weird. It's not a slow leak either; it just goes completely flat suddenly when you check it. And come to think of it, one of the times it even punctured while sitting in her car. Considering all this, the only explanation is the existence of a supernatural being known as the "Puncture Mister." He must be sneaking into a solo-living customer's house or car with a mysterious spare key, puncturing her tires, then sneaking into her bedroom to lick her cheek while she sleeps, and putting his spit in the barley tea in her fridge before leaving. When I told her not to worry, it was just "Puncture Mister," she said "That's way too scary!"
Since she mentioned the tire might be the problem, and it was something we sold at the shop, I replaced it with a new one. After that, whether "Puncture Mister" found peace or whatever, the mysterious air loss incidents that had been happening frequently stopped. Since I wanted to prove that the original tire wasn't the cause, I drew something like a rabbit on the tire's sidewall with a permanent marker, then asked the customer to draw something next to it. What she drew next to my rabbit—that's where the title "Dora-Mine" comes from. I've been using the Dora-Mine tire ever since, and it still hasn't punctured.
August 10th
This is my first morning ride since putting on the Dora-Mine tire. The location is Oku-Mizuma.
I'm not using this saddle bag anymore.
This is
Dora-Mine!
August 27th, pretty much the same place.
November 7th. I'm riding at a time that crosses sunrise while out in the mountains, but
rain started falling. I didn't photograph it clearly, but this day too it's the Dora-Mine tire. I haven't changed it since putting it on the front wheel.
This is the condition as of today (December 6th). Still no punctures.
As for Dora-Mine's appearance, it looks familiar from somewhere, but don't think about it too hard.