Wonderful story, Jean-Marc; many thanks for posting. John Saxby wondered...
I don't have any answer for handling the duiweltjies -- met those wee devils 12 years back on a weeklong trek in the Naukluft. Maybe Dan, who now & then has to deal with goathead horns, will have some advice.
I can share my experience and solutions, which are different from what others seem to use use. I prefer to use my Schwalbe Dureme tires in goathead thorn country (in my case, America's Great Basin and related desert regions) and have had reasonably good luck using standard Schwalbe PV13 tubes and *carrying* a pair of Mr. Tuffy liners, which I *install* when I reach areas with goatheads. I have found the Mr. Tuffy liners work better than other brands I've tried.
In this way, I avoid undue wear from the liners on the majority of my journey, yet benefit from their increased puncture resistance.
There are some provisos, of course:
• As mentioned, I don't ride with the liners all the time, just when I feel they are needed. This sometimes means I do incur one puncture before I install the liners. I find it pretty quick and easy to install and remove the liners, about the same effort as repairing a puncture.
• I pre-shave the ends of the liners into a bevel using my disc sander. This prevents the ends/overlap from wearing through the tube, possibly causing a flat on their own through friction.
• I use a piece of tape with low-creep adhesive to cover the end-joint overlap; same reason as the beveling.
• I boost my tire pressure by about 5% over my ideal (~15% rim drop under load) bare tire/tube pressures. This isn't much, but I've found it is just enough to prevent squirming between tube, liner, and tire casing.
• I do adjust my riding style and try not to lean over too far in corners, as the liners don't extend up the tire sidewalls, which can remain vulnerable.
• Whenever I stop, I remove any visible goathead thorns partially embedded in the tire tread. I don't have as much trouble if the thorn embeds in a tread block, but the thorns are more problematic if they embed in the thinner part of the casing between the tread blocks.
The season seems to make a real difference wrt how many thorns I encounter. They seem to be far worse in the late summer/early fall. Rainfall makes a difference, too. Wet rubber cuts far more readily than dry rubber (any high school chemistry student can testify that wet surgical tubing cuts far more easily with single-edged razor blade than dry rubber), so I've found my tires to be extra vulnerable to thorns when riding during and immediately after thunderstorms. These thorns are opportunistic to a degree and "like" to proliferate in disturbed soils, so it pays to stay away from road shoulders and such.
I do ride pavement as well as gravel and off-road (cross-country). I find these three environments don't really affect the incidence of thorns very much -- they blow across pavement, ride atop gravel and dirt, and are sprinkled across vegetation as vines. One benefit of riding across dry lake beds and through largely undisturbed areas is they don't seem to support goatheads -- it is just open playa, usually with high concentrations of alkali salts. The big concern is getting out on it and having unexpected rain or thunderstorms occur. Playa is usually hard and solid to a degree, but when it gets wet, it becomes pudding and one sinks. Worse, it sticks to and coats pretty much anything in contact with alkali water that is very irritating to skin.
Even more than my tires/tubes, I worry about goathead punctures to my tent floor and self-inflating pad. I always sweep and groom my campsites to reduce the incidence of thorns (Ouch! Fingers!) and sometimes take a closed-cell pad and lay it out *beneath* my tent floor, which serves to blunt any unfound thorns and so prevent some punctures to tent and mattress in that way.
Unlike a majority of users, I have had simply terrible experience in my desert touring with flat-preventing sealants including Stan's. I think the source of the problem is the extreme heat I encounter when touring the desert in summer. It can get hot enough to melt asphalt and cause it to stick to tires or oneself if you sit on the pavement (with terrible results when it cools and you try to peel it off taking the hide with it). I think the heat basically cooks the goo and converts it to little snot-balls that clog valves and don't seem to do much in terms of remaining liquid enough to seal punctures.
I've not had great luck with puncture-resistant (thicker) tubes, either. They always seem to be thinner around the valve and that's where they seem to pick up punctures for me in my use.
I typically carry 6 new spare tubes, start on new tires (and carry 1-2 new folding spares in plastic zip-top bags inside lightweight dry sacks to slow rubber degradation), and carry a number of both vulcanizing and instant patch kits and my usual tube of beta-cyanoacrylate super glue (the kind that glues rubber...I pinch a puncture so it opens, put in a drop of glue, let go, and the leak is sealed within a few seconds. I use small drops of water, sometimes with alcohol from the stove and with baking soda as a kicker/accelerator and filler for larger holes in tires and to fill cracks in case something made of plastic cracks and needs repair. Desert humidity can be very low so the water -- even spit -- helps to cure the glue).
Maybe something in the above will help. Goatheads and related thorns are bedeviling little things, and almost every defense against them is vulnerable to a degree in my experience. They're no fun when they stick into skin, either. I got some in an elbow and both knees one night as I leaned over to unzip my tent door. Sure did hurt.
Best,
Dan.
