djb

in all seriousness, what did you learn from these two flats?

did you see clear and evident proof of what caused the flat, ie piece of glass, wire still sticking in tire?
was it a pinch flat due to underinflation?
what weight did you have on the bike, ie what were the pounds of stuff in panniers and pounds of you? What pressures did you run?

as you can see, using co2 cartidges is a waste imo, and causes waste also, but more importantly if you havent identified the reason for a flat, they are one shot deals.

if we assume the flats were because the tires were either getting thin, or are so so tires, you can see why its worth getting good quality tires and having new ones or at least in good shape before a trip--simply to avoid the pain in the keester and time waste of dealing with multiple flats.
Unless it was bad luck, and if your tires were in good shape, do look at the tire pressure factor.
also consider getting a pressure gauge or a pump that has a gauge, so you can actually keep track of pressures for a given weight situation, good for future references.

most importantly, we all hope you both had a fun time, croissant flat fixing experiences aside.

MidLife50

I relied on the bike shop on flat #1. For flat #2 I found a pinhole in the tube and then used a cotton ball to diligently search for a cause. Finding none I changed the tube and carried on.

I'm right at 200lbs and I carried 28 pounds of panniers/load on the back. I was running about 85lbs in the back tire (+/- 75 in the front).

Definitely had a good time. Appreciate all the helpful advice. Thanks.

Tourist in MSN

That is unfortunate.

You now have had twice as many touring flats as I have had. Odds are now that you won't have any for years to come. Or, your rear tire is jinxed and more will come soon and frequently.

djb

cant recall if this was said, but to help id where a hole is in tube, or even in tire if an unseen thingee isstill in it, position the tire so that the brand name is lined up with the valve hole, that way you have a rough known placement of rim/tire/tube

you saying that you couldnt find the object in tire, sometimes it helps to really look with reading glasses and to actually flex the tire where you know the hole was made in tube, and sometimes a hidden little wire or glass piece will then show up.

as said, if you keep getting flats, consider getting a better rear tire.
thats usually been my thermometer of "ok, this tire is getting tired....."

your pressures sound ok, they are 35mm 's right? but really only you know if the tire is overly bulgy or soft feeling at those pressures with your bike loaded.
hope thats the end of flatsville for a while

Tourist in MSN

Yup:

csport

MidLife50 , what Bontrager tire do you have?

I am asking because I have done the GAP/C&O multiple times. In the very beginning I was paranoid and rode Marathon Plus Tours. Then I tried lighter and more supple tires like Conti Speed Rides (the rear one exploded near Cumberland) and Vittoria Voyager Hypers. Never had a flat on the GAP/C&O, and I attributed this to the natural surface and the absence of the glass shards. (On the Erie Canal trail I had about 5 flats in one ride, 4 of which were caused by small pieces of glass I picked on road in the cities; to be fair, the rear tire was also somewhat worn.)

Last November I rode the DC to Pittsburgh, and after the 5 flats on the Erie Canal I decided to mount a stronger rear tire, a Bontrager H5 Hard-Case Lite. I thought it was bombproof for the purpose and I took a small pump with no gauge. I had a slow leak like the one you describe, lost some time and as a result I had to ride the last hour to Hancock on WMRT in the darkness (with the light I had). I did exactly what Tourist in MSN and djb said, but I could not find the cause of the flat. Also, the leak was exactly at the seam, so I blamed a tube defect for that. The next day I have a slow leak again. I figured it was at the same place (I align the tire label with the valve as described here) in the new tube. Then I realized there was something with the tire, and I could not find it. I talked to the shop owner, describing the situation, and he installed a new tube (they warranty the repair), removing a small splinter.

Next day everything is fine, and the day after that I have a slow leak again. I was so desperate that I just bought the last 700x42c tire at Ohiopyle and threw away the Bontrager tire. Probably I could have glued some patch to the tire or inserted a dollar bill, but I was so frustrated by this hard-to-find tire defect. To rub the salt into the wound, the next morning the tire was flat again because the glueless patch I had applied to the tube did not hold -- again, the puncture was near the seam, and I did not sand it enough.

Another good reason to carry a spare tire on a tour

Do you get any more flats in this tire after the ride?

Tourist in MSN

Several years ago I had a similar problem, could not find why my tire kept causing minor punctures in my tubes. After two or three flats, I took one of my flatted tubes that had not yet been patched, and skipped the patch. Instead I surgically removed the valve stem and put a slit all the way around the tube. That tube became my tire liner, no more flats after that.

MidLife50

Bontrager H2 Hard-Case Lite, 700x35c...and the leak I found was also on the tube seam.

Tempted to think it was a bad tube but maybe time for new tires as well? Back home now but did need to air it up a bit for a short ride. This time I told myself that I was merely replacing CO2 that leaked faster. If it leaks anymore definitely go tire shopping.

djb

Bicycle tubes do lose pressure over time, how much pressure in how much time varies.

If you really want to check things, remove tube, hold carefully underwater with some air in it, will show up pinholes possibly.

axolotl

3 years ago, I was touring with a couple of friends in the gorgeous Dordogne valley in France. I went into a bike shop and I was chatting with the shopkeeper/mechanic who was interested in my Bike Friday folder, when 2 British brothers in their 20s came into the shop with a fancy road bike. They spoke almost no French and the shopkeeper spoke no English, so I soon found myself translating. One of the brothers was repeatedly getting flats in one of his wheels and came into the shop to buy some more tubes. I think he said he had had something like 8 flats in just a couple of days, though he didn't have a flat at that moment. They had driven to the shop. The shopkeeper had a bunch of questions, as did I. The British cyclist couldn't answer a single question. He hadn't attempted to look for a reason for his flats, so he had no idea if the flats kept happening in the same spot, which seemed likely. He hadn't checked to see if a piece of glass had gotten embedded in the tire tread, for example, or if a spoke was puncturing the tubes from the rim side of the tube. With each flat, he would simply put in a new tube. The cyclist thought that perhaps his tire pressure might have been the reason, but the mechanic checked the pressure, which was correct for those tires. The cyclist left after buying about 10 new tubes, but he said he'd pay attention the next time he got a flat. After they left, the shopkeeper & I shook our heads.

Carbonfiberboy 

The above are all great suggestions, at least the ones I read. Whenever I ride a bike outside, I have with me 2 tubes, a patch kit, boot kit, and a spare tire. I always use folding tires. If I flat, I change both the tube and tire. That saves time and frustration. I worry about why later, in camp or at home. It's quite a bit quicker to do that than to try to find the cause on the road. The patch and boot kit are belt and suspenders. I have used them.

I don't use CO2, Road Morph G only.