swampdonkey90

Pump up my back tire. Ride 30 miles. Come home. Tire pressure is good. Go to ride again 2 days later and tire is flat. Pump up tire. Ride 30 miles. Come home. Tire pressure is fine.

Change inner tube.

Pump up back tire. Ride 30 miles. Come home. Tire pressure is good. Go to ride again 2 days later and tire is completely flat.

My presta valves are closed correctly. Im confused.

Furthermore, the inner tube I took out ..... I pumped it up and left it in the garage for a few days and it did not go flat when not in the tire.

What the hell is going on ????

MNBikeCommuter

Best guess without being able to inspect anything is that it's a high-pressure leak, most likely caused by a steel belt wire shard still stuck in the tire. The hole could easily be too small to notice much pressure loss with just the tube pumped up. I'd pump it up a bit and run it through water to see if there are any bubbles. Take your time as there probably won't be a fast rate of them.

Rand

I am a noob with Bikes but Ive managed automotive repair and tire stores for a long time.When we get a tire with a hard to find leak the first thing we do is spray it down with a squirt bottle with soapy water.It bubbles where the air is coming out,remember to spray down the valves too.

fogrider

change the rim strip on the rim and check the stem hole.

Machka 

Have you done a good inspection of the tire?

KBentley57

air innertube up to appreciable PSI, submerge in tub, find leak. If it is deflating, the air is going somewhere.

jrobe

Tubes are $5. Install a new tube. I wouldn't even both trying to find the obvious slow leak.

Machka 

But he did change the tube ... and the second one went flat too. He needs to have a really good close look at his tire before he puts another tube in there. It could be a tiny piece of glass, or a miniscule wire, or something like that.

To make finding whatever it is easier, the OP should have marked the location of the tube valve on the tire before removing the tube ... then located the hole in the tube ... then matched the tube to the tire ... then looked for the flat cause in the location of the hole. But it is too late for that now, and he's going to have to check the whole tire.

MONGO!

wire thread stuck in the inside of the tire

swampdonkey90

Im thinking this. I do I isolate this ?

And does the valve stem length make any difference ? The last ones I bought are markedly shorter. I cannot imagine that the length changes squat but aesthetics but its the only noticeable difference in the tubes I have.

oilman_15106

OP - you may inadvertently unscrewing the valve body(core) when you are airing up the tires. If the valve core is not all the way screwed down you may have a very slow leak. This only applies if the tubes you are using have a removable core. If so take a set of needle nose pliers and screw in the valve body real tight.

swampdonkey90

Damn....the washer that holds the stem comes loose routinely too. I hope it is that simple. These issues always come down to something obvious.

So before my next ride I should tighten the valve stem washer with pliers, inflate and hope for the best ?

Machka 

No ... before your next ride you need to check your tire or you're going to end up in the middle of nowhere with a flat. Have you checked the tire yet? Checking the tire is the obvious solution, although can be a bit time consuming. Tightening your valve core is not as obvious.

And the washer that holds the stem makes no difference whatsoever when it comes to flats ... it can be tight, loose, or off all together.

swampdonkey90

I will certainly change the tube in the morning and look for a shard of some sort. I just did not know if the valve stem meant squat or not. I have both tubes that went flat sitting in my garage pumped up and they are not going flat ( 3 days on the oldest tube) and its this phenomenon thats has me scratching my head. The tubes fatten every 2 days in the tire but are fine three days pst removal from the tire.

Machka 

Quite likely because there is something in the tire that is poking a little tiny hole into the tube. When you ride, you're putting pressure on the tire, and whatever it is that is poking the hole in the tube ... and you're putting pressure on the tube so the air is squeezed out the little hole ...so the tire goes flat.

When the tube is just hanging there, it may still have the little tiny hole in it, but there's no pressure squeezing the air out, so it could be quite some time before it goes flat. If you were to squeeze the tubes (and especially squeeze them in water as others have mentioned), you'll likely find the hole. That would be important if you were planning to patch the tube.


If you check the tire thoroughly, very thoroughly ... sometimes those little bits can be very hard to see ... and if you find nothing, the next thing I'd check is the rim and rim tape.

Atavar

Tell yur kids to quit letting the air out of your tire.

bitingduck

Any chance you're using latex tubes? If not, then it's probably a tiny piece of glass or michelin wire, as already suspected.

swampdonkey90

Little metal shard stuck in the tire. Was able to line up the hole from the last tube and locate the shard. I can see how I missed it but man what a pain in the rear end !

Thank you for your help.

Da Sherm

What will really grind your gears is trying to figure out where you ran that over to get it stuck in the first place. Glad you found the culprit of your leak

swampdonkey90

Glad to post that after a 55 mile ride this afternoon in which I rode in some terrain not becoming a road bike.....I have no flats to report.

Machka 

Excellent! Those little metal shards and wires can be so annoying.

Scrockern8r

I figured it had to be the baby bike bolt hooligans...