Like most roadies, I get the occasional puncture out on the road - am running Conti GP5000 and Pirelli P-Zeros with (quality brand only) tubes. However, much more common is for me to go to take the bike out of the garage, and find the tyre flat. Often I can’t find a hole in the tube; it may even hold air when pumped up, but I prefer to replace it anyway. Other times the tube is holed, yet I’d ridden home and parked the bike up a few days earlier with no indication of a problem. What’s the story?!
How much time guess by between rides? I assume you’re not using latex tubes, which always lose air between rides. I find some butyl tube and tire combinations don’t hold air well over time (but are fine to ride with).
It could be something sharp on your rims, you might check the rim bed.
Less likely explanations are some crazy weather shifts where you live, or maybe you’re using CO2 cartridges to fill your tires, and that leaks quickly.
When you say “flat” when you come out to the garage, do you mean 100% flat or just soft?
Some air loss can be expected, especially if you are using latex tubes (as noted above). Even some butyl tubes can be a bit porous if they are lightweight tubes.
Also, how are you checking for holes on those times you say you can’t find them? Are you also inspecting the inside of the tires for anything stuck in it? If not, you may have a small piece of debris coming through the casing that is causing your recurring flats.
I’d check the rim bed and reapply the rim tape if necessary.
c’mon man, you know the drill; check EVERYTHING, clean everything, carefully reinstall, make your own ‘luck’.
edit- if you’re not using latex tubes, maybe use those. use talcum powder for smoother installation.
Yup. This tends to be a lesson people learn the hard way (once); after a puncture, they replace the tube and ride on, only for a repeat in 5-10 minutes. Then usually they do the same again, and… you guessed it, out of spares. At home, having had to call in the cavalry, they discover the small flint or thorn that has gone far enough through the tyre to be invisible from the outside but is poking out, into the tube, on the inside.
go over inside of tire like it’s a crime scene.
Thanks for the responses, but I don’t seem to have expressed myself clearly enough. These are NOT repeated flats; I puncture on a ride every 6 months, but find the tyre flat (yes, zero pressure) at home every 3-4 months. Sometimes I find a hole in the tube, by pumping it up and feeling for escaping air - that means it has holed on the ride, but not deflated until some time after getting home. I’d maybe understand that if the tyres got significantly warm during a ride, but I don’t think they do, so what’s the explanation? Other times there’s no hole, and the tube holds air (though I replace it anyway, not wanting to risk another deflation while riding); so what’s happened there, can valves fail intermittently?
I’m using butyl tubes (mostly Contis), don’t use CO2, the bikes get ridden every few days and normally lose pressure at 5-10 psi per week. It is absolutely not an issue with rim tape or anything stuck in the tyre. I’m looking for an explanation, but also curious whether this is a common experience (the responses so far suggest not)?
That was the reason commonly given for aligning the tyre label with the valve hole, it meant you could concentate your search in the likely location of the intrusion.
Now it just seems to be part of cycling snobbery.
Rodents. Mice. Squirrels. Your kids. The mechanical action of the valve and instant result of air hissing out can be very attractive to kids.
So, every once in a while, 3 or 4 times a year, you get a flat while the bike is parked in the garage, and “sometimes” there is a hole–“sometimes” is more than once, so, let’s say you now have unexplained flats once or twice a year–which means you’re now asking for a generalized explanation for what could be one-off occurrences–in one case there may be a tiny slow leak that you missed by your visual inspection (pump it up and put it in a bucket of water to check for small leaks), other times the valve may be old or faulty, while still others, the tube itself may be old, fragile or improperly made, etc.–all enough to allow for leaks. I don’t think the problem as you have described it indicates a consistent reoccurrence of the same problem, so, likewise, I don’t think there is any one explanation that needs to cover the problem(s).
(As an aside, I have used a lot of Conti tubes in the past, and I don’t find them very robust, or long lasting, myself–I usually avoid them, while I love their tires).
Probably just an indication that you generally get very minor punctures that deflate very slowly.
Ie - not fast enough to notice while on the road but enough to go down overnight.
That accounts for the difficulty of finding the puncture when you try and fix it.
TBH far better to have this sort of puncture to one that goes down immediately!
You have smaller punctures that slow leak at night. Next time fill your sink or a bucket with water then submerge the inflated tube under water and check for bubbles, keep checking section by section, the bubbles may be very small but it will be there. Also check your tire thoroughly in the section you discover the leak. Often times there is a small shard of wire or a fragment of a thorn that gets stuck in the inside of the tire but is absent from the outside this will allow you to have a slight leak that stays inflated but flats overnight, if you’ve changed tubes and this is still happening that is the likely culprit.
You can patch your tubes as well, haven’t had to buy a tube in years, James has an article about this, Rema tip top, silly to bin a whole tube for a tiny pinhole.
also, check that your valve cores are snugged up enough, don’t over tighten.
I have also experienced this phenomenon. I’ve even pulled the flat tube out and pumped it up, can’t find the hole, then leave that tube inflated and watch it not lose any air for several days even though it went flat in the tire over night after my ride. I’ve found the best solution is to have multiple bicycles in rideable condition so the random flat doesn’t stall the ride for that day. Any time I think I may have too many bikes, the flat tire scenario is what justifies keeping them all.
you guys have some crazy spouses or kids is the most plausible explanation.
After I patch a tube, I inflate it (not on a rim/tire), and leave it hanging in the garage. For a butyl tube, it should keep air for several days at least. Even a small puncture that is barely visible under water or with soap will leave the tube deflated after 12-24 hours in my experience.
This is my standard for ‘holding air’ after a patch job. IMHO anything less rigorous leaves a good possibility of missing a very slow leak.
Also, I would check to see how tightly the valve is closed when you find these deflations. Maybe once or twice a year you forget to tighten the presta core adequately after pumping up?
My take is either the air leaves through the valve, or through a hole. (Assuming butyl tube here, as the amount of air they lose through the rubber is quite small.)
I would encourage you to investigate these mystery deflations more meticulously next time - I don’t think there is any great insight to be had from the details given.
I’ve actually had this happen to me over the years. A couple times I pumped up the tire and it was fine again for another few weeks and then flat one morning.
For me it turned out to be a bad valve stem/ extended connection once. But all the other times I was equally perplexed. I ran latex and corsas for reference. (When I say flat one morning, I don’t mean the normal air loss due to latex tire- I mean like 5psi after one night)
Alternatively, inject some orange seal in there and forget about it.
I’ve noticed this happening more frequently in the past few years. When I have checked the tube under water, I find the valve is leaking very slowly - as little as a bubble every few seconds. I suspect the mfg quality of tubes has deteriorated as a result of supply chain changes. There are likely batch to batch variances with any manufacturer. But, of the ones I’ve used, Conti’s were not good and I don’t believe I have seen it yet with Michelin/Schwalbe.