Get On, Clip In, Fall Off

Pssshhh

Cycling. Punctures. Two things which often go hand in hand, especially if you insist on riding around places like London where it seems that the streets aren't paved with gold (very slippery, bad for traction anyway) but fragments of broken glass and grit. My bike came supplied with 28mm Bontrager Race Lite Hardcase tyres, designed to withstand the rigours of life, with Kevlar anti-puncture belts. Well, after a few days of commuting I got a rip in one of them which meant that I had a nice surprise when I got back to my bike after a day in the office. So much for them - their puncture protection was about as useful as homeopathic insect repellant during the Scottish midge season. The tyre wouldn't have lasted long even if repaired, so I called in the heavy mob in the shape of a pair of two Specialized All Condition Armadillo monsters.

Armadillo tyres are basically considered to have the best puncture protection in the business, and they're what people always recommend when you're not desperately worried about weight but find fixing punctures a bit of a bore. They have nice red sidewalls, and were fine until I noticed the regular scraping from the back indicative of the wheel rubbing on something. I took a look and found a big bulge over the tyre, and seeing as I'd forgotten the lessons I learned as a kid assumed that this must be to do with overinflation and let a bit of air out. The bulge went away. I let some air out of the front tyre too, just in case.

A couple of days later, I'm turning off Camberwell New Road and "pssshhh" - down goes the front tyre, in a matter of seconds. "Huh?", I think. "These Armadillos suck!". I found a little hole in the tyre wall right down almost at the bead, fixed the inner and rode home carefully before the hole grew too much. Another tyre written off, because, well, I just don't trust damaged tyres. The back tyre turned out to be at about 40-50psi (recommended - 70-100), so I think I may have been a little overzealous with letting air out when I thought they were overinflated.

Of course, they weren't overinflated. I'd just forgotten a basic lesson of my youth - when you fit a new tyre, push the valve into the tyre and pull it back out again so the rubber seal around the valve is inside the tyre, not between the bead and the rim. That's what had caused the bulge in the rear tyre. I'm undecided as to whether the front puncture was due to underinflation or due to what looked like the brakes rubbing very slightly on the tyre sidewall and weakening it (the 100km Audax ride I did a weekend or two ago had some very brake-heavy descents on it, so they'd have certainly heated up a lot).

This time the shop only had 25mm Armadillos, so we've got a spare slightly used 28mm and I have two new tyres yet again. Let's see how long it takes before the next "pssshhh" - in the meantime, I'm re-learning important things I need to know about how to maintain bikes competently.

Posted by mpk at August 22, 2006 10:37 PM | TrackBack