Gear: The mystery of the delayed tire puncture

Six months ago, I wrote about how much I love Specialized Roubaix Armadillo Elite tires. I decided that I would praise them in a review if I could ride them for 1,000 kilometers without a puncture. I ended up getting 1,250 kilometers out of them before flatting. That’s amazing for the post-apocalyptic road conditions in Guangzhou.

Unfortunately, I stopped keeping track of the mileage that I put on the tires, but I ended up getting several thousand more kilometers out of them before my next – and last – flat. Eventually, the sidewall on the back tire split and I had to retire it. I’ve replaced the set with a new pair of Roubaix Armadillo Elites. I’m still their biggest fans.

The tires spoiled me, though. When I used to ride Continentals, I’d get three or four flats each month. With so much practice, I perfected my tire-changing skills. Within minutes, I’d be able to slap a new tire on and be back on the road. But the Specialized tires made me rusty. And I made an amateur mistake the last time I flatted with them.

I’ll let you try to figure out what I did wrong: I was coming home from a long Sunday ride when I punctured about 18 kilometers from my home. When I took the tire off, I ran my fingers through the inside of the tire to check for nails or other nasty bits that might have caused the flat. I also checked the tire’s tread for any pieces of glass or other nasties. I didn’t find anything, so I figured it must be a valve problem or a defect in the cheap tube I bought at Decathlon.

I got home without another flat, so I figured it must have been a defective tube. But the next morning, the tire was flat again. I inspected the tire again, eyeballing it closely and using my fingers to feel for sharp objects. I found nothing. The inside of the rim was clean and I wiped it down again. I used a knife and tweezers to pick out several pieces of glass and slivers of stone from tire tread. I pumped up the punctured tube, immersed it in water and noticed that tiny bubbles were coming from a tiny hole. Hmmmm.

After installing a new tube, I went out for a ride, and 15 kilometers into it, I punctured again! After another inspection and change, I found nothing. I wondered: How is it possible that I’m able to ride 15 kilometers before puncturing?

Now’s the time to guess what was wrong.

That evening, I did another inspection, and I realized I had made a rookie mistake. When I ran my fingers through the tire searching for culprits, I was only working in one direction. When I reversed direction, my fingers immediately hit something. It was a tiny fragment of what looked like piano wire. I imagine it got lodged in my tire a long time ago and had been slowly working its way through the rubber. My fingers were running right over it because it was sticking out at a 45-degree angle and would bend when my fingers went over it. But when I went against the grain, it pricked my finger and was easy to find. It wasn’t long enough to immediately puncture the tube, but after 15 or so kilometers, it could gradually pierce the rubber.

Lesson learned: When you inspect your tire, make sure you run your hands through it in BOTH directions.