Flats galore! Could it be something other than bad luck?

[tulip]

have you checked the rims to see if any of the spokes are poking through the rim tape? Do the rims have rim tape? But... you said there are no holes? Did you fill the tubes with air and check? Confusing.

I've had problems with valves before. And my old pump was so poorly made that it damaged valves. Barring that. Are all the pieces of your bicycle pump screwed together properly? They can loosen and cause valve issues.

+1 for spokes and rim tape. If that's the case, the shop needs to fix the wheel and rim tape and reimburse you for tubes you have gone through. Are the wheels true? What is the max PSI?

[DebW]

If you can find a hole in the tube (using a bucket of water), then you'll know if it might be a rim or spoke issue based on where the hole is. But sometimes slow leaks (which you have since they only go flat over night) are impossible to find. Maybe check the inside of the tire again very carefully with your hand, tissue paper, or a balloon in case something is barely sticking through.

[Fredwina]

What about the tires? Lot of Flats for me are a sign that I need to buy new tires

[OakLeaf]

^ That's my experience too, I just couldn't remember whether you bought the bike new or used. Nowadays I track tire mileage, but before that, basically my rule was unless I knew I'd run over something crazy, if I had two flats in short succession I replaced the tire.

[finnporter]

I've had a faulty valve on my bike once. I only noticed what it was after all the new tubes didn't have any holes. To check, I turned the wheel so the valve wouldn't be on the bottom or the top but somewhere sideways. Hold a hair or two in front of the valve and if it moves, air is coming out. Don't do it outside though or anywhere you'd expect a draft.
The guy in the bike shop did the same thing to check, only he used his lighter and checked if the flame would move away from the valve.

[OakLeaf]

Here's another thing that occurred to me: if you inflated the tire with CO2, it will go flat overnight because the molecules are much smaller than the N2 molecules that make up most of room air, and especially in a high pressure tire, they will filter out through the tube material itself. So if that was the case, there could be no hole and your tube could still be good! Some people make a habit of completely emptying a tube that was inflated with CO2 and re-pumping it with air after then get home. Me, I just plan on putting extra air into it before the next one or two rides.

You can also check valve integrity the same way you check for holes in the tube wall, either by dunking in a pail or sink of water, or by smearing soapy water or spit on it.

[colorisnt]

Hmm thought I replied here. Guess not! They found the source of the flat. It was a tiny (smaller than a pen) few CM long piece of metal wedged under the rim, so now it's taker care of. No more fiats despite 44mi yesterday! Rims are taped and all that. The bike and tires) oe brand new as well. It wasn't a valve either although we've had issues with that before. It's the reason I won't go to one shop in town. They sold me a faulty tube w) valve issues refused to replace it an hour later.