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A bike / map geek with a gadget obsession and a high-viz fetish. by Vannevar Bush       about       /       murals       /       Pgh-DC bike maps new

Friday, July 29, 2011

LBS to the Rescue: Flat 1, Flat 2, Rim Tape and Glass Shards

7/29/11 #222


Met R. for a ride on the Panhandle Trail. Uncharacteristically, I got to the rendezvous a half-hour early and got all my accessories aligned on the bike (a non-trivial task) only to find a flat rear tire, so I had time to change it and was almost complete with the change when R. pulled up. He did not appear empty handed; he had scored some newer maps of the Panhandle Trail, and that excited my I-M-G (inner map geek).

I'm not eager to have a flat tire, but it's a task that's good for my self esteem in that I'm somewhat capable of it. This flat tire came at a perfect moment - I was still at my car so I could use the bike rack as a work stand, I had three spare tubes with me; it was warm, daylight, and dry. Unfortunately, I was unable to diagnose what had caused the flat.

Changing the flat is a necessary but insufficient task; one needs to ascertain why the tire went flat and address the cause, or else the new tube will meet the same punctured fate as the previous tube. I could not find any cut, gouge, wire, or object that might have caused the flat, so I simply replaced the tube and set off, hoping for the best but knowing it was likely to happen again.



We rode west on the Panhandle Trail, from the Montour Trail in McDonald to Burgettstown. The trail is in excellent condition along this segment. West of Burgettstown the trail is quite primitive until the West Virginia line, when it resumes with a high-quality packed limestone surface.

Some local riders have been making an overnight trip starting in Coraopolis on the Montour Trail, joining the Panhandle Trail to Wierton, and then riding the Wheeling Trail to Wheeling WV, some 65 miles.

The Panhandle Trail is in very pretty country and sees far fewer people than the better known Montour Trail. At Burgettstown we exited the trail to stop for a cold drink at a convenience store, which has closed shop since last summer. A kind lady stopped to direct us to the local McDonald's for a cold drink.

As we set out to the Golden Arches, I saw that my rear tire was flat again, after only 9 miles of riding. R and I worked together well, we marked the puncture point and it was in the same vicinity of the first flat, but we couldn't find anything that might have caused the loss of pressure. I put a second tube on the bike, leaving me with one more tube (and if needed, a patch kit to repair the damaged tubes). Given the unexplained leaks on the rear wheel, I asked R. if we could just return to our cars and call it a ride at 18 miles, and he agreed.

The ride back was pleasant and uneventful. In a most-perfect-world, the tire would have gone flat at the trailhead, offering another carcass as evidence; but it was not to be.

I took the rear wheel and two punctured tubes to my Local Bike Shop (LBS), Ambridge Bike Shop, and explained that I had something going on that I couldn't figure out. It was educational to watch their diagnostic inquiry.

They noted that one puncture was on the inside of the tube, and the other on the outside. The rim tape had moved off track, exposing several spoke flanges and leaving gaps where the pressurized tire would herniate into the newly available gaps - replacing the rim tape resolved the issue with the leak on the inside of the tube.

The puncture on the outside of the tube was more puzzling, until they started flexing and testing the tire casing, when a gash holding shards of glass became visible. You couldn't see it if you'd simply looked at the tire, you had to stress the casing to make it apparent.

The tire was beginning to show threads here and there, so we replaced the tire and resolved the issue with the leak on the outside of the tube.

Although the new tire calls for inflation to PSI, they took pains to only inflate it to 75 psi, explaining that 75 psi in the air conditioned shop might easily exceed 80 psi in the heat outside. That's one of the things I love about those guys.

I purchased a few tubes to replace the two I'd used, and also bought a few water bottles with the Ambridge Bike Shop logo - you've got to wear the school colors, and these bottles have a new spout mechanism that seems to work well.

A hot ride on a little-used trail, and a chance to visit the LBS and watch mastery at work: not a bad day.

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