Scott commented that a flat tyre could make life difficult 60 kms from home. This picture is of 2 inches of my front tyre. All those white spots are thorns embedded in the tyre. The big ones are 2mm thick. I haven't been into deep bush for a couple of weeks, there are more embedded thorns immediately after a trip.
I rarely have a flat tyre with my current system, and I will ride right over thorns on the mtn bike. In the bush of maasai land it is pretty hard to avoid thorns, even on a maintained road.
However I also take a spare tube, many patches and glue, tools, and stuff like spare spokes. I might even take a spare tyre. I wont ride with someone on a serious bush ride unless they have a similar system. PERIOD.
My system is thorn resistent almost thorn proof. Not the tyres as much as what is inside. My front tyre has kevlar in it and thick. Then I have a 3mm plastic liner between tyre and tube that breaks most thorns and makes the tyre thicker (goat skin also works). Then heavy duty tubes(5 mm thick). THEN I have what is called "slime" in the tube. Slime is the real key. Even if a thorn gets though the 3 layers the slime seals the puncture. If I get a big hole ( > ~3 mm) the slime doesn't seal well, and I might have to patch the tyre.
As I said I can ride my bike over inch long thorns and they either break off or eventually make a pin hole in the tube but it gets sealed by the slime. There are probably a couple thousand holes in a tube that has been in the tyre for awhile. After a trip if I take the tyre off the are a hundred thorns poking through. Sometimes I don't use the thick tubes, the slime works really well.
Needless to say the tyres they are heavy.
Sometimes you have to add air during a ride a few times until it seals all the holes. This usually happens when you hit a rock right where a big thorn was and it gets pushed further in. Sometimes it is just divine justice and the tyre goes down.
On the third day of the Tarangire trip my tyre kept going down. The usual method is to stop and pump it up hard, spin the tyre as fast as you can to spread the slime and then look and see if there is a huge thorn or a place you can see the flourescent slime oozing out. Then you ride on and hope you don't have to repeat the process. Well this time after 3 times we decided we needed an inspection.
Hmm! Somehow I had a thin tube on and there was slime all over the place inside the tyre. I think that the slime in that tube was salvaged from another tube and watered down. El cheapo wanted to save a couple $.
Wes deadpans " that is a pretty thin tube you got there". Which actually meant "What the hell you doing coming out here with a thin tube."
I think we put a different tube in at added a bit of slime and rode on with no problem.
Hmm I like talking about bikes. I wonder if I am in the wrong profession!