#$%^&!@* pinch flats!

Got up and out earlier than usual yesterday morning. My wife is on the local Advertising Federation cycling team that rides in the Hill Country Tour for AIDS, and they have regular training rides leading up to the Tour. It was in the 40s, overcast, and breezy, and Mrs. Noob decided she wasn’t riding. But I was.

I assumed it would be just a few Ad Fed folks, but when I got to the elementary school where the ride starts, I found it was a full-blown training ride organized by the Tour. At least 50 people turned out. There were even three SAG vehicles.

This was an easy ride, because it’s still early in the season. A number of riders were even more noobie than the Bike Noob. Lots of hybrids, even a few cruisers, and some riders in mid-weight jackets and blue jeans. The route was the Mopac loop I take all the time. One loop is eight miles, and riders had the option of doing as many as three.

The ride organizers explained the route and procedures. They passed out cell phone numbers of all the SAG vehicles. They went through all the common hand signals. Then it was time to leave.

I was among the first half dozen riders out of the parking lot. The wind actually wasn’t as bad as it was for the last couple of weekends, and I had dressed right, even wearing full-fingered gloves, so I was all warmed up by the time I got to the end of the first lap.

Going around the second time, I picked up a little speed over the first lap. A couple guys passed me on a downhill, but I passed them back going uphill. As I approached the intersection with a major road, I checked behind me to see if it was safe to cross over to the left shoulder and prepare for my left turn. It was. Still looking back, I started my turn to cross to the left. When I looked back to where I was heading, I saw it — then I hit it.

“It” was something squarish. There was no way I could avoid it. My rear tire went flat immediately. I stopped on the left shoulder, assessed the damage, then walked the bike back across the road to change the tire next to the right shoulder.

Once I got the tire off, I did the usual inspection to try to find whatever caused the flat. But I could find nothing. Remember, these were the new Kevlar-belted tires I bought just last week. I was displeased. I checked the tube, but a cursory examination there turned up nothing, either. Unfortunately, when I ride, I wear prescription sunglasses that have only my distance prescription, and not my bifocals. So I can’t see anything close unless I hold it inches from my eyes.

I pulled the spare tube from my seatbag, and had just about got it and the tire back on the wheel when one of the SAG vehicles pulled up. He held the wheel while I pumped up the tire. We put it back on the bike, and I packed up my seatbag.

When I turned back to the bike to resume the ride…the tire was almost flat again! The spare tube must have had a leak! Defeated, I put the bike up on his carrier, and he drove me home.

Back in my garage, I grabbed the first tube that had flatted, and took a closer look at it. There it was: the “snake bite” — two small punctures side-by-side. Whatever I had rolled over caused a pinch flat.

I blame myself on two counts: I didn’t see the thing that caused the flat (it turned out to be a a small rock, about three inches across by two inches thick — it was still in the road when I rode by it this afternoon), and I probably didn’t have enough pressure in my tire. If you saw last week’s post about the new tires, you know I planned to experiment with pressures to find what was right. I had already ridden at 100 pounds, and for this ride, I was down around 95 — maybe a tad less.

The late Sheldon Brown, my main source of information for all things bike, says tire manufacturers are conservative when they put recommended pressures on the sidewall. Brown says if the tire bears a 100-pound load, a 25 mm tire can be pumped up to 110 pounds. Since I weigh about 210, that’s about 105 pounds per tire. Hutchinson recommends a tire pressure of 101 pounds max.

This afternoon, I pumped the tires up to 100 pounds again, then went for a ride. No problems. I may still fiddle with pressures, but they’ll be firmer, not softer. And I guess if I find the energy this week, I’ll be patching two old tubes.

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2 thoughts on “#$%^&!@* pinch flats!

  1. It’s a fine line…pinch flats if you’re underinflated, more puncture flats if you’re overinflated. I ride at the high end, and take Sheldon’s sage advice.

  2. Pingback: What’s Your Tire Pressure? « Bike Noob

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