Latex tubes with GP5000 tires?
"High performance group rides." 
05-01-21, 04:23 PM
#52
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This is a timely thread for me since I have finally decided to update from 25c Bontrager T2 Tires which are hardshells with significant tread thickness. They are 350g and advertised as training tires with very long treadwear, ideal for use in spring/fall. I originally bought them when I was getting in to road biking and thinking that it would be good to get something that had a lot of tread and wouldn't puncture, so I wouldn't have to buy tires too often.
I have a 1990 trek 420 which isn't a light bike, and with my group I continually drop off the pack. Part of this is due to my lack of bike fitness, but I think a fair amount could be due to the significant RR of the tires. Looking up RR's of different tires I see a hardshell tire like continental gatorskin are double the RR of the GP5000's (and i expect my t2's are even worse). To put some numbers to it, one source I found shows a pair of gatorskin 25c needing 35W and a pair of conti 4000's needing only 21W at the same speed (18mph).
I am upgrading to Conti 5000's with a latex tube in the rear, since I understand the majority of the weight is distributed to the rear and i'm not fully committing to latex yet (pinching pennies). Hoping that this will help me keep up with the pack. I understand the need for me to improve my bike fitness, and having a wider ratio might help that too (21 speed), but I am expecting to see some improvement with these tires and a latex tube.
www. bicyclerollingresistance .com/ specials/grand-prix-5000-comparison
With a latex inner tube, they measured the 5000's to be only 8W at 18mph, so for two i'd be looking at nearly 20W savings. I think in terms of money spent, that should be a fair return on the dollar.
With respect to patching a latex tube, is it the same glue and patch material as butyl tubes?
I have a 1990 trek 420 which isn't a light bike, and with my group I continually drop off the pack. Part of this is due to my lack of bike fitness, but I think a fair amount could be due to the significant RR of the tires. Looking up RR's of different tires I see a hardshell tire like continental gatorskin are double the RR of the GP5000's (and i expect my t2's are even worse). To put some numbers to it, one source I found shows a pair of gatorskin 25c needing 35W and a pair of conti 4000's needing only 21W at the same speed (18mph).
I am upgrading to Conti 5000's with a latex tube in the rear, since I understand the majority of the weight is distributed to the rear and i'm not fully committing to latex yet (pinching pennies). Hoping that this will help me keep up with the pack. I understand the need for me to improve my bike fitness, and having a wider ratio might help that too (21 speed), but I am expecting to see some improvement with these tires and a latex tube.
www. bicyclerollingresistance .com/ specials/grand-prix-5000-comparison
With a latex inner tube, they measured the 5000's to be only 8W at 18mph, so for two i'd be looking at nearly 20W savings. I think in terms of money spent, that should be a fair return on the dollar.
With respect to patching a latex tube, is it the same glue and patch material as butyl tubes?
05-01-21, 06:41 PM
#53
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I'm not as sceptical as some of you that Crr is constant with rider position. I think it at least possible. That said, I have 3 questions:
1. If this effect occurs, how large is it?
2. If this effect occurs, in which direction is it? Aclinjury thinks that Crr increases but could it also have the opposite effect?
3. If this effect occurs, what method would be sensitive enough to measure it, and how would the experiment be run?
1. If this effect occurs, how large is it?
2. If this effect occurs, in which direction is it? Aclinjury thinks that Crr increases but could it also have the opposite effect?
3. If this effect occurs, what method would be sensitive enough to measure it, and how would the experiment be run?
05-02-21, 07:50 AM
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I'm not as sceptical as some of you that Crr is constant with rider position. I think it at least possible. That said, I have 3 questions:
1. If this effect occurs, how large is it?
2. If this effect occurs, in which direction is it? Aclinjury thinks that Crr increases but could it also have the opposite effect?
3. If this effect occurs, what method would be sensitive enough to measure it, and how would the experiment be run?
1. If this effect occurs, how large is it?
2. If this effect occurs, in which direction is it? Aclinjury thinks that Crr increases but could it also have the opposite effect?
3. If this effect occurs, what method would be sensitive enough to measure it, and how would the experiment be run?
https://forum.slowtwitch.com/forum/S...3F_P7305959-2/
In general, rolling losses will be a good bit higher for standing climbing than seated climbing, and this can be partially offset with higher front and rear pressures.
and
What I can tell you so far is that seated vs standing testing shows us that Crr can be quite a bit higher when standing, that the effect is different for different riders, and that it does seem to be affected by tire pressures with higher pressures reducing some of the losses when standing, but not enough to get to the seated numbers.. the other interesting one to add here is the torsional forces/wind up in the tire casing under hard standing efforts on very steep grades..
05-02-21, 09:00 AM
#56
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Another potential cause of higher Crr while standing and climbing could be the force with which one pedals while standing, since you are able to shift weight aggressively and almost hop side to side, the hopping can be considered added force to the force of one's bodyweight. Since Crr is a function of normal force, this suggests the rolling friction could be higher when standing.
Combine that with the torsional wind up in the rear tire as it rolls along, those two phenomenon could increase the losses relative to seated climbing. I'm not suggesting this effect is massive, but the theory seems to suggest at least some increase.
I wonder if the little park tool self-adhesive patches would work on latex. Probably not a permanent solution but maybe enough to get me home. Doesn't bother me to pump each road ride, on a commuter I do not pump each time.
On the topic of latex tubes, there seems to be some differences of opinion around whether or not 'feel' is enhanced or decreased with a latex or butyl tube on the front. Since I have a steel frame and fork bike I tend to feel the road quite well anyways. I think I will try some rides with the new Conti 5ks and latex tube in the front (for 'feel') and then in the rear (for the extra watt or two difference).
Combine that with the torsional wind up in the rear tire as it rolls along, those two phenomenon could increase the losses relative to seated climbing. I'm not suggesting this effect is massive, but the theory seems to suggest at least some increase.
On the topic of latex tubes, there seems to be some differences of opinion around whether or not 'feel' is enhanced or decreased with a latex or butyl tube on the front. Since I have a steel frame and fork bike I tend to feel the road quite well anyways. I think I will try some rides with the new Conti 5ks and latex tube in the front (for 'feel') and then in the rear (for the extra watt or two difference).
05-02-21, 09:34 AM
#57
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Josh Poertner briefly mentioned/alluded to something like this in this thread:
https://forum.slowtwitch.com/forum/S...3F_P7305959-2/
https://forum.slowtwitch.com/forum/S...3F_P7305959-2/
05-02-21, 05:09 PM
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This Vittoria Pit Stop Road Racing Tube and Tire Repair Kit looks like a possibility. Has anyone tried it?
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05-02-21, 06:34 PM
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I've been giving speedy roadside puncture repair of latex tubes some thought, too.
This Vittoria Pit Stop Road Racing Tube and Tire Repair Kit looks like a possibility. Has anyone tried it?
This Vittoria Pit Stop Road Racing Tube and Tire Repair Kit looks like a possibility. Has anyone tried it?
05-02-21, 10:15 PM
#60
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I've used latex tubes in both tires on our tandem and my singles for many years. They work fine. They patch fine with the usual patches and glue. They do lose air more slowly from tiny holes. Their only drawback IME is that one has to be very careful pumping a latex tube up to find the leak. They develop a balloon with just a touch too much pressure. That means that the only good way to find a leak is to pump only 2-3 strokes from a floor pump, then immerse in a sink. With a butyl tube you can pump the heck of it and then feel for the leak with your lips. I use Rema patches and glue, buying the patches in boxes of 100.
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05-02-21, 11:07 PM
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05-03-21, 09:08 AM
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You perceive no difference because your boundaries of "performance" is narrow, like riding at a constast speed in a straightline.
However, when I'm talking "performance", i'm talking about many factors, like high-G cornering while trailbraking. This is where I'd use latex on the front, this gives me great road feedback into my arms and fingers that are squeezing the lever, and feedback translate to confidence at higher speed.
I personally don't use latex because of its slightly better rolling resistance compared to butyl, main reason being the higher cost of latex.
As for tubeless. I won't use the if the tire size is not at least 32c. Tubeless tires have sidewalls that are too hard (it's necessary for tubeless), and to compensate for the hard sidewall, people run at lower psi. This is fine going in a straightline. The problem is high-g corners. Lower pressure makes the tire tend to "fold" in high-g corners, this gives an ambiguos road feedbak to the fingers. A highend clincher like Veloflex or Vittoria with latex doesn't do this, you can run them at higher psi (to avoid the "folding" feeling) while still getting great road feedback due to the suppleness.
I could also make a counter argument about using tubeless (with low psi) in fast group rides. Low psi will feel like you're acclerating in mud out of corners, and fast group rides we do this a lot, repeatedly, and if you gradually lose positions at every corner, then it's only a matter of time you'll slip off the back. In this setting, I don't care about comfort or rolling resistance, I care about instant acceleration where I won't lose the wheel of the guy in front.
Not everyone is out there doing high-g corners, but than again not everyone is interested in riding in a straight line at constant speed all day either.
The debate of tubeless, regular clincher, latex, butyl,... to me is choosing difference horses for different courses. In the car world, I don't want to bring a soft and comfty truck tire to a road course with flip-flopping high-g corners.
However, when I'm talking "performance", i'm talking about many factors, like high-G cornering while trailbraking. This is where I'd use latex on the front, this gives me great road feedback into my arms and fingers that are squeezing the lever, and feedback translate to confidence at higher speed.
I personally don't use latex because of its slightly better rolling resistance compared to butyl, main reason being the higher cost of latex.
As for tubeless. I won't use the if the tire size is not at least 32c. Tubeless tires have sidewalls that are too hard (it's necessary for tubeless), and to compensate for the hard sidewall, people run at lower psi. This is fine going in a straightline. The problem is high-g corners. Lower pressure makes the tire tend to "fold" in high-g corners, this gives an ambiguos road feedbak to the fingers. A highend clincher like Veloflex or Vittoria with latex doesn't do this, you can run them at higher psi (to avoid the "folding" feeling) while still getting great road feedback due to the suppleness.
I could also make a counter argument about using tubeless (with low psi) in fast group rides. Low psi will feel like you're acclerating in mud out of corners, and fast group rides we do this a lot, repeatedly, and if you gradually lose positions at every corner, then it's only a matter of time you'll slip off the back. In this setting, I don't care about comfort or rolling resistance, I care about instant acceleration where I won't lose the wheel of the guy in front.
Not everyone is out there doing high-g corners, but than again not everyone is interested in riding in a straight line at constant speed all day either.
The debate of tubeless, regular clincher, latex, butyl,... to me is choosing difference horses for different courses. In the car world, I don't want to bring a soft and comfty truck tire to a road course with flip-flopping high-g corners.
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05-03-21, 10:40 AM
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Rolling resistance is produced by a complex 3-dimensional deformation of rubber in and around the contact patch. As I stated earlier, it is not obvious to me how this rolling resistance might change with wheel angle.
I'm definitely not the world's expert on rolling resistance, but I'm guessing that it's not obvious to whoever that world's expert is, either.
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05-03-21, 11:47 AM
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I run latex tubes in 4 bikes. The bikes have Conti GP 4000s (700 x 25c), Conti GP 5000 (700x 28c), Vittoria Corsa G (700 x 28c), and Rene Herse Barlow Pass (700c x 38c). All 4 bikes ran butyl tubes previously. Maybe I'm guilty of confirmation bias, but I think I can tell the difference on all 4 (latex better, more compliant ride).
If you want to read about the science of supple tires, tire pressure, and rolling resistance, read material published by Jan Heine (Rene Herse) and Josh Poertner (Silca). Reading their research and conclusions helped me to understand my personal bike and riding circumstances better, and how to optimize.
Tire pressure is critical. More is not better. I set my tire pressures using Silca's excellent pro calculator. The recommendations from the calculator were softer (lower) than the pressures I was running. Do the work and actually measure the installed width of your tires on your rims. Comfort on the road has improved, I don't feel that rolling resistance has suffered, and I have more confidence in corners and bumpy descents.
If you go latex, definitely carry butyl as a spare tube. Use more care and visual inspection when mounting to make sure the tube isn't caught between tire bead and rim. Inflate to 15 psi or so and inspect. I've had no problem patching the latex tubes and re-using them. I have had a couple of latex tubes where I've had many tiny pinhole leaks (abrasion damage from inner sidewall) where I've had to toss the tube.
If you want to read about the science of supple tires, tire pressure, and rolling resistance, read material published by Jan Heine (Rene Herse) and Josh Poertner (Silca). Reading their research and conclusions helped me to understand my personal bike and riding circumstances better, and how to optimize.
Tire pressure is critical. More is not better. I set my tire pressures using Silca's excellent pro calculator. The recommendations from the calculator were softer (lower) than the pressures I was running. Do the work and actually measure the installed width of your tires on your rims. Comfort on the road has improved, I don't feel that rolling resistance has suffered, and I have more confidence in corners and bumpy descents.
If you go latex, definitely carry butyl as a spare tube. Use more care and visual inspection when mounting to make sure the tube isn't caught between tire bead and rim. Inflate to 15 psi or so and inspect. I've had no problem patching the latex tubes and re-using them. I have had a couple of latex tubes where I've had many tiny pinhole leaks (abrasion damage from inner sidewall) where I've had to toss the tube.
05-03-21, 03:21 PM
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I run Latex tubes and Conti 5000. Great combination. It is my everyday set up. Just take a little time installing them. Make sure you can't see any pink as you seat the tire. also good to talc them some before installing. I have had very few flats while running latex. If you wear your tire down to the cords they will flat just like butyl.
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05-03-21, 03:50 PM
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Silca latex tubes and GP5000s for the last two years without a single puncture or pinch flat (prob over 15k miles). I carry a butyl tube for a spare because it's easier to swap out roadside. A bit more care is needed when mounting latex tubes, but they're not nearly as fragile as people make them out to be. Follow Silca's video on how to mount them and you won't have any problems. Ride and handling is fantastic. I check my pressure before every ride anyway, so pumping them up a bit each day isn't an issue for me.
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05-04-21, 10:28 AM
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On the very next ride after I wrote this, I punctured. Argh! Plus, the spare tube failed immediately after inflation.
Moral: Never say that you rarely puncture. The flat tire gremlins hear you and immediately put a curse on your bike.
Moral: Never say that you rarely puncture. The flat tire gremlins hear you and immediately put a curse on your bike.
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05-04-21, 05:53 PM
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Yea and I have had long periods of no flats only to find the spare rotten when the time comes.
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10-15-21, 05:36 AM
#70
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I gone thru 4 tubes now, mine always fail around the valve, just a few mil away from the stem. Anyone have this problem, or better yet, know a fix? I have old Mavic 622-13 rims, could that be the problem? Thanks
10-16-21, 12:43 AM
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It's because I ignored the recommendations for installation from Silca/Vittoria.
In a tutorial video on their website (hosted on YouTube) Silca strongly recommends using tubeless tape. This includes punching or cutting a minimal hole to accommodate the Presta valve stem.
I didn't do that. I already had some stiff plastic rim strips (Schwalbe high pressure, and some other brand), so I wasn't concerned about the tubes extruding into the spoke holes. But the pre-punched hole in the rim strip for the valve stem was a bit oversized. And that's where the hole occurred after about a year. Gradually the latex extruded into that tiny space between the hole and valve stem, slowly weakening until it developed a slightly elongated tear and slowly leaked out.
So when I installed a new set of Vittoria skinny latex tubes (they make the 700x25-30 latex tubes rebranded by Silca), I used Gorilla tape. I used an ice pick to punch a minimal hole. I needed to apply a bit of pressure to squeeze the valve stem through but it should hold better. It's only been a couple of weeks so we'll see. It took the first set a year for one to go bad.
And if it happens again, okay, yeah, fine, I'll use tubeless tape. But some folks have already reported good results using Gorilla tape for tubeless, so I'm betting this installation will be fine.
BTW, if this sounds like a lot of hassle, it's not really a big deal. Latex seems to be more puncture resistant than butyl, and certainly rides better. I don't notice any significant difference in speed, but it's much more comfortable on our increasingly rough coarse chipseal roads. Even at near-maximum pressure in 700x23 tires, it's comfortable compared with butyl.
Regarding repairing that damaged latex tube, I wouldn't. I've patched the one puncture I've had using a Lezyne self adhesive patch, no problems, it held for a year. But I don't see any way to properly patch the irregular surface at the base of the valve stem where the latex material is overlapped and glued. But I've heard other latex tube users say they've successfully cut up old latex tubes to make patches with Rema adhesive. So I'll save my one latex tube that failed at the valve base.
Last edited by canklecat; 10-16-21 at 12:51 AM.
10-16-21, 05:21 AM
#74
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I’ve actually seen this and did exactly what this said, I used a tubeless tape, 2 wraps, etc. For some reason, the tube weakens around the valve hole, and eventually flattens. It must be moving or…? My latest solution is 2 patches to either side of the stem!
10-16-21, 05:55 AM
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Could you share what your specific pre-ride pressurizing practice is? Like what type of pump are you using and what kind of pump head does it have? Fussing with pushing or wiggling the valve for me made this area fail (on 3 or 4 latex tubes (both Vittoria and Challenge brand). The smooth valve stem I was pushing it in a little each time I inflated my tires and since latex have to be topped up before each ride, this area of the tube takes more stress than butyl. Latex tubes could benefit from threaded presta stems that take the little nut to keep them in place.
I just posted a picture of my smooth presta stem holder on a thread yesterday. Was that you Bamicus asking on a different thread? Just curious. Here is another photo of my 6mm nylon locking stop collar: ….sorry my photo library says “downloading from iCloud” - will try a bit later.
Anyway: since I went to these collars on my latex tubed bike, the issue with failed valve stems has not recurred.
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