Foggy up on Skyline this morning

wolhIMG_6998
Guess it had to end sometime, that string of just simply awesome weather. Sunday we were able to ride without leg warmers or base layers, but this morning we were reminded that not every day will be perfect. Darn.

Kevin (my son, not the pilot), Eric, Karl, Karen, JR and… the return of Nigel! Nigel from the UK, that guy who doesn’t bother coming over here unless he’s fit enough to ride most of us into the ground. Nigel and Eric rode on up ahead, while I was trying to keep an eye on Kevin, who was lagging behind a bit. Apparently Sunday’s ride took more out of him than expected, although I think his sore legs would have been much better had he ridden to work and back yesterday, instead of getting a ride with his sister. I held up for Kevin at the big clearing although this time I stayed far enough ahead of him that I didn’t have to worry about the usual sudden surge/second wind on his part and he goes flying past me. That’s right, I don’t trust him.

The fog was all along Skyline and the west side of Old LaHonda, causing slick enough conditions that Kevin almost took a spill in front of Nigel descending Skyline towards Sky Londa. Depending upon your point of view, Kevin was either incredibly-skilled to avoid hitting the pavement, or riding just a bit too fast for the conditions.

Oh, right, forgot to mention the young woman wearing the Stanford kit that joined us up on Skyline. Mentioned to her that this is a regular ride, which she said she already knew (and for whatever wise reason decides not to show up). Australian accent, I think.

Print Friendly

Mystery flats near the valve? Maybe not so mysterious!

Those two bulging spots near the valve? They are *not* weak spots in the tube! Or at least they weren't weak/defective when installed. Read on.
Those two bulging spots near the valve? They are *not* weak spots in the tube! Or at least they weren’t weak/defective when installed. Read on.

Another “mystery flat” in the shop¬†today, one that had previously seen three unexplained tube failures, but today that would end. You see, I’ve been down this road before, a road that goes like this- a tube, no matter how thin or defective in one section, cannot be forced to bulge because it’s held in place by the tire. Anything you see that looks like a bulge or rupture usually represents some external force in play.

This particular tube was leaking at one of those bulges. No surprise there; they look scary and the rubber has thinned out. But how? Nothing funny about the rim or tire.

Closeup, showing the lines to the right of the valve, where the tube has developed leaks from being stretched too thin.
Closeup, showing the lines to the right of the valve, where the tube has developed leaks from being stretched too thin.

Here’s how it happened. During inflation, the person pumping up the tube is pushing the tube’s valve up into the tire, creating a cavity underneath. As the pressure increases, the tube fills in underneath, bulging downward into that cavity. That’s how you get those funny spots either side of the valve. Over time, sometimes not too much time, that thinned-out tube fails. In the smaller photo, you can see what look like small cuts; those are the areas the tube has split and now leaks.

What to do? Make sure you’re not pushing the valve up into the tire as you pump! Especially if you’re inflating a tube that already has a fair amount of air in it, since pushing it upward under those conditions pretty much guarantees the tube is going to try and bulge in to fill the empty space. ¬†–Mike–

Print Friendly