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November 01, 2017

The Zen of Bicycle Tire Changing

Mary and I just spent a wonderful five days biking down the coast of Portugal from Porto (from whence Port Wine gets its name) to Praia de Sao Pedro de Moel. Much of the ancient forest we cycled through had burned to a crisp in the last few months (more in a future post). The beaches were wonderful; the weather atypically beatific for this time of year.

We were on an unescorted tour which meant that our bags magically got from hotel to hotel but that we were responsible for getting ourselves and our bikes from place to place. There was a GPS with a track on my handlebar and we had fairly detailed maps so navigation was simple except when you needed it most – getting in and out of cities, especially over a bridge which required instant decisions on whether there was a bike path on the outside of the guardrail, a wide shoulder on the inside, or just ride in traffic and pray. We did some of each but not always the right choice for the bridge we were on. Portuguese drivers, however, are understanding and forgiving.

Besides a GPS and a burn phone to call for help, the tour company provided us with a repair kit. I paid little attention during the briefing since I haven’t had a flat in five years of riding in Vermont. I do have a tire repair kit at home which daughter Kate gave me and I had leafed through the instructions once.

Day two. Mary stops fairly suddenly. “Bear, I think I have a flat.” Yup, the rim of her rear tire is on the gravel bike path (actually, as we saw, gravel and glass). Front wheels are easy to takeoff. On these bikes removing the back wheel means disentangling the gears from the chain, big opportunity to get covered with grease. But what you really need to be paying attention to is the relationship between the sprockets, the chain, and the derailleur (the thing that keeps tension on the chain). I didn’t.

Next step is to use three handy shims that were in the kit to get one side of the tire out of the rim. At this point Mary had found instructions and was reading to me as I worked. We did have spare tubes so I didn’t need the patch kit. Mary, as instructed, felt around the inside of the tire and did find and remove a piece of glass which was waiting to puncture the new tube.

“This #### tube is too big for the rim,” I growled.

“Partially inflate the tube to make it easier to handle,” Mary read from the instructions. I did; now it more or less fit. For no good reason I had removed both sides of the tire from the rim but finally figured out one needed to be replaced, then the tube put on, finally the other side tucked back in. Easier said than done. I had 300 degrees of tire in the rim.

“You are now at the hardest part of your task,” Mary read. “It is preferable that you tuck the tire in with your fingers rather than use a tool which may puncture the tube. Most important is patience.” Yeah, sure. But finally the whole tire was back on the wheel. I inflated it with the hand pump, screwed the cap down tight on the stem, and got the hub hopelessly entangled with the chain because, of course, I hadn’t paid attention to how I removed it. Fortunately, we had my intact bike to use as a model of what the reassembled rig was supposed to look like so, lots more grease stains later, it was all put back together.

Just as I was ready to triumphantly turn the bike right side up, I noticed that the new tire was completely flat!

More in despair than hope, I pumped it up again. This time I heard the air hissing out from the valve as I screwed the cap on. I backed off from tightening the cap and the hissing stopped. Put some more air in, put the cap halfway on, and were back on the road. Total time 1 hour, 15 minutes. Had to skip lunch.

Next day my back tire went flat. Couldn’t inflate the first new tube I tried; pump just wouldn’t move. We had asked to have extra tubes dropped with our luggage so had another which did inflate. Total time of repair 20 minutes. I’m educable.

But I also like to think of myself as an engineer by inclination if not by training. Thought a lot about the tires the next night. The valves were different than what we’re used to in the US: Presta instead of Shrader.

Screenshot-2017-10-30 bicycle tube valves - Google Search

Maybe, I thought, the little valve on the top needs to be turned to open and then turned again to close BEFORE the cap is put on. That would explain both problems. I tried partially unscrewing the cap on the tube I hadn’t been able to inflate and then pumping. It worked.

“I’m going to fix the valves on both the tubes I replaced,“ I told Mary before we started off on the next leg. Managed to deflate both. Theory was right but practice more difficult. Total time lost 35 minutes. In Vermont they say “if it ain’t broke, don’t fix it.” But you know engineers.

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