Puncture vine (tribulus terrestris), also known as goat head thorns (The photo is from Google Images), is a big problem for bicyclists in several parts of the United States and also in a number of other parts of the world. It is certainly a problem in southwestern Idaho where I live. Even if there are no puncture vine plants in your immediate neighborhood, the thorns tend to blow into places where they did not grow. They have a knack for finding your bicycle tires. They are 100 percent effective at causing your tires to go flat.
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I have decided a sealant additive is my best choice. I use Slime, which is a brand trademark. My bicycle tubes use Presta valves, which are thinner than the more common Shrader valves found also on all automobile tires. It is easy to remove the valve core from a Shrader valve, add Slime to the tube, and replace the valve core. Presta valves have their broadest part inside the stem so that it is impossible to remove the core from the tube.
Another Instructable slit the tube with a knife, inserted the Slime through the slit, and added a tire patch. The problem with that approach is that the least amount of Slime on the surface of the tube makes it impossible for a tire patch to stick. This Instructable will show you how to drop the valve core inside the tube and put it back in place after adding Slime to the tube. In the interest of disclosure, this basic procedure is described on the Slime website. I have illustrated it here with some things I learned by experience.
Slime coats the inside of your tire tube as your wheels roll. When there is a leak, the air moving through the leak draws some of the Slime into the hole and tiny shreds of rubber plug the hole. A tube with Slime added can last a very long time after a leak developed and sealed, even at pressures of 100 pounds per square inch.
Another Instructable slit the tube with a knife, inserted the Slime through the slit, and added a tire patch. The problem with that approach is that the least amount of Slime on the surface of the tube makes it impossible for a tire patch to stick. This Instructable will show you how to drop the valve core inside the tube and put it back in place after adding Slime to the tube. In the interest of disclosure, this basic procedure is described on the Slime website. I have illustrated it here with some things I learned by experience.
Slime coats the inside of your tire tube as your wheels roll. When there is a leak, the air moving through the leak draws some of the Slime into the hole and tiny shreds of rubber plug the hole. A tube with Slime added can last a very long time after a leak developed and sealed, even at pressures of 100 pounds per square inch.
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Puncture vine is known locally as "Goat head" and the dry burrs bust into chunks with two spines each that really do look like a goat's head or a bull's head, which is what we called it in Colorado. The geometry of these is such that one of the two thorns always points straight up when they lay on the pavement.
Slime and Presta valves: It is worth using on 28mm or larger tires. I find that the slime won't seal the higher pressure needed for narrower tires. It will seal for 50mm or so, then break loose and spray for another 10meters, wash, rinse, repeat. Finally when my glasses have enough slime spots on them I will stop and patch it. I have had good luck with it in 28mm tires run at 80psi, so it might eventually keep the air in a narrow tire after enough air leaks out.
The slime does make the holes easy to find! Yes, you need to get it all off or the patch won't stick. I carry alcohol wipes in my tool kit for this purpose, and they are also good for cleaning grit out of road rash, and slime and gnat spots off my glasses.
Slime has a tendency to settle when you're not riding and throws the wheel off balance until it distributes to the perimeter. This impacts control negatively, for example: I ride a road bike and try to only stop to rest at the tops of hills. This makes sense as far as preserving momentum goes, but with the addition of slime I'm given a choice of two problems. I'd either need to be on my brakes for the first few hundred meters, likely losing any benefit of stopping on a hill, or, alternatively, I can deal with an unstable ride and have to apply a lot of effort and concentration to keep the bike on the road and moving in a straight line as I hit 40mph.
Slime is wonderful on mountain bikes, though, where there is a high probability of punctures and a heavier tire makes the effect negligible. I use slime pre-filled presta tubes for my mountain bike.
Off to search for foam inner tubes for the roadie.
I have a observation;
why not just buy the tubes that slime offers, that already have slime and are
presta valved. Slime has been offering this for some time now... or maybe
you wanted a challenge... That's it. It is all about the challenge. ;)
http://www.spinskins.com/bike-tire-liner-race.html
(mine are orange and black)
You buy the size you need and don't have to cut anything so there would be no rubbing through, I put a set in my slicks years ago and have had no issues what so ever. Before the liners I have punctures all the time.
Hope that helps.
He never described in detail exactly what the problem was but from what I have divined I think the Slime made it impossible for him to get a patch to apply correctly. I could tell by his expression and demeanor that Slime was a touchy subject with him and I never pressed him on it.
Personally I use thorn proof tubes. They're not totally impervious but they work pretty good. Thorn proof tubes do have a couple of downsides like they are so thick they can be hard to mount and they're so heavy they're well, just heavy!
But this is about avoiding flats right?
After the automotive slime is put in the tire, the tire needs to be spun at high speeds to use centrifugal force to repair the tire, something done via driving the car. Since most people use slime when they have a tire blowout, they are not in a position to drive on their tire, so they just dump slime in their car. All the slime settles to the bottom of the tire.
What happens then is that there is the tire becomes imbalanced, with a weight on one side of the tire, the tire will never run correctly again. (A car tire is tubeless and wide, the slime will just pool in the bottom of the time). You will feel the car "thump" as you drive. The only way to fix it is to pull the tire completely off the rim and scrape out all the slime by hand.
He probably even had to clean Slime off his tire machine afterward too. So I understand why it ticked him off.
I linked an Instructable in which the author intentionally slit a new tube so he could insert Slime. Then he patched the slit he made. There I noted that the least bit of Slime on the outside surface of the tube will keep a patch from adhering. That is probably the objection your friend who services tires has to Slime. If a tube filled with Slime does break open, especially inside a tire and rim, it is a mess. Fortunately, Slime is water soluble and it does clean up, but your tire feels like Will Smith and Tommy Lee Jones in "Men in Black."
I did use the tire liners you mention. The ends often need to be feathered or the ends, themselves can rub through the tube and cause a flat. I had that happen a couple of times and stopped using them because of that problem, even though I had feathered the ends. My aim with this Instructable was to describe how it is possible to get tire sealant into a Presta valve tube, so that is why I did not mention tire liners.
I will pass this on to a few of my racing bike cycling friends who have been wanting to use slime but where not able to because of the presta valves.
In Ireland the problem usually come from the thorns of the blackthorn in late summer when the roadside hedges get cut by flail mowers and the thorns are scattered everywhere, I have Kevlar lined tires on my bike and I still manage to pick up thorns.
Originally I was using Presta tubes and slitting the tube then resealing. This was extremely problematic, with several disasters. I blew several tubes in bike storage during hot (Australian)summer days when the tubes got hot and literally exploded slime bike tyre and tube in a huge annoying mess.
I solved this by converting to schrader valve tubes (requiring drilling of rims to accept the 9mm tube stems). You can avoid this if you use Presta tubes, by using tubes with removable valves (harder to find than this method, but easier to do).
Slime and other generic brands are a different solution to STANS and Stans tubeless products. In my area when commuting Tubeless solutions work well, however the weight of the Slimed tubes is worth while when commuting, as often Tubeless will run out of air pressure before sealing. I prefer to commute with slimed tubes for this reason (more convenient) as i've "collected" twenty Goatheads in 50 metres in one ride (still able to ride the last 5km's home without needing to pump up the tire)
An observation I have made is if you have Goat heads in your area, with kids riding BMX and MTB bikes avoid riding on grass and grassed edge tracks where the kids ride and learn what the flowers look like so you can avoid the plants in spring.
As an aside the Goathead or Caltrope was exported from South Africa in the late 19th century to Australia and South America as cattle food, I can't understand why thought.
On that note, if the valve core is steel, would it be worth using a neodymium magnet to hold it closer? Not that I'm suggesting anyone goes out and gets one specifically for this, but it would make the "inch-worming" quicker, I should think.
I don't actually use Presta valves myself, so may be talking a lot of hot air ;-)