The story began when I left the Dahon for a couple of hours in the office of a company where I work sometimes. However, when I came to cycle back to my own office, I noticed that the front tyre was flat as a pancake. I had a quick look to see if there was anything obvious sticking in it but on discovering nothing untoward, I whipped out the pump and reinflated. I cycled back to the office without further incident.
I generally use "Slime" in the tyres on my bikes - a self-sealing compound designed to plug small leaks as they happen.
I have had some very positive experiences of its ability to seal a puncture (especially on a cold, dark night when changing a tube or fitting a patch would have been more of a pain). However, I am starting to go off the stuff and I'll explain why...
My usual experience of punctures has been that one either notices the offending thorn or piece of glass/wire/roadside detritus sticking out of the tyre or a small quantity of the delightfully green "Slime" goo leaking out before it plugs the hole. However, in this case, I found neither and have to confess that my first reaction was that someone had played a schoolboy prank and let my tyre down. I resolved to have a look later on and see what was up but as the tyre inflated well and stayed inflated, I didn't bother and then ultimately, forgot altogether.
Anyway last week, during a bit of routine maintenance, I decided to remove the tyre and take a look. I found that I did indeed have a puncture, as evidenced by the amount of green stuff wetting the inside of the tyre. Much more disturbingly, I noticed that the tyre, where it had been in contact with the leaky patch had worn right through one layer of reinforcement. I didn't get a picture but the damage was a patch anout 5cm by 3cm where the inner layer of fabric had completely worn away. Clearly this is not a good thing for the structural integrity of the tyre! I have little idea how it happened, except perhaps by the "Slime" lubricating the surfaces of the tyre and tube allowing them to rub against one another while the tyre rotated.
As a secondary matter, I also found that I had a smaller hole in the inner tube which I'd never even noticed had happened. To be honest, it's not the first time that a puncture has gone unnoticed but it is the first time that other, more serious damage has been concealed.
I changed the tyre to an old one I have as a spare (one of the original Dahon Rotolos) and cycled to work the following morning as usual. However, it did get me thinking about the disadvantages of "Slime":
- It's easy to get a puncture and never even notice. OK this is the point of the stuff but if having a bit of slime sloshing around in the tyre after a leak is going to cause damage, it kind of defeats the object.
- I've also found that when patching the damaged innertube, the "Slime has a tendency to push out of the leak underneath the patch and unstick it from the tyre. Not a good thing on the move and infuriating when trying to repair a bike late at night before needing it for the commute.
However, every cloud has its silver lining. As I had to replace the front tyre, I took the opportunity to replace the rear as well with a pair of these:
I've long wanted a pair but have always stopped short of forking out. However, I have heard and read such good things about their robustness that I spent the extra to find out how good they really are. My first impression is that they are very sturdily built tyres and the thickness of the tyre crown is impressive indeed. It would have tobe a long, sharp and tough foreign body in order to make its way through one of them to cause a puncture.
My brother-in-law has done thousands of touring miles on Marathons and trusts them to the point that he no longer carries patches or a tube. I'm a little less certain and know that the day I don't have a repair option will be the day something makes its way through one of them. However, I won't be using "Slime" in them. At the worst I'll get a puncture on the aforementioned cold, wet ride home and have to pull into a garage/shop/mate's house to swap the innertube. I've carried out this operation so many times now that I'm much more confident of my ability. The only time in the past when this strategy has failed was when I couldn't actually remove the rear wheel because of the poor quality of spannner I was carrying. I now carry a good quality adjustable one so that won't be an issue again.
Hopefully I won't have to eat my words but I'll let you know how I get on.