I went out early this morning, about 9:00 (which is early for me, on a Saturday, anyway; normally at that time I'm still trying to figure out whose underwear I have on, if I happen to have any on. But that's a story for another time.) I aspired to another 50-miler, but after 20 miles or so, I had a flat. The back one, of course. No problem--like any well-prepared cyclist, I put in a new tube, after having checked the tire for whatever may have caused the puncture. I found nothing and assumed that whatever caused the puncture had come and gone. An erroneous conclusion, it turned out.
Five miles or so later, again came the sickening feeling of a mushy back tire. I pumped the tire up, went a quarter of a mile, pumped the tire up again, went another quarter of a mile, and realized all hope that the problem was a loose valve or some such easily fixed problem was in vain.
I didn't have another tube. I didn't have any patches. I didn't even have any of that disgusting slime stuff that never works, and anyhow, how do you get it into a Presta valve? Did I just claim I was a well-prepared cyclist?
The options didn't look attractive. Call for help? Unthinkable! Stuff the tire with grass? That's gotta take forever, and be a mushy ride into the bargain. Ride flat and ruin my tire, not to mention the wheel? No.
Once upon a time, I read an article in Bicycling magazine that said a last resort is to cut the tube in two at the site of the leak, tie a knot in both ends, air it up, and ride. At the time, it sounded kinda bogus--I mean, come on, a knot? How much air can that hold? And of course, I had no knife, but I did find the sliver of gravel that caused the leak by doing what I should have done the first time: I aired up the tube sans tire, spotted the leak, and knew exactly where to look in the tire. Sure enough, an almost microscopic bit of limestone, ready to ruin tubes I didn't have all day.
So I tied a very tight knot in the intact tube, with the leaky spot outside the loop, aired it up, and rode. Amazingly enough, it worked. A bit of a bumpy ride when the knot came round, but it sure beat the alternatives. I made it home, and managed to get 35 miles in. Not a bad ride.