Dan The Man

I have 25c tires pumped up to around 90 psi on my regular commuter. Recently somehow the front tire has gotten this really annoying slow leak. It will drop about 30 psi a day. It's enough that I can always just pump it up in the morning and ride all day long, but if I leave it over the weekend, the tire will be at 15 psi by Monday. I know that I should patch it, but I also know it will really suck to try to track down something that tiny, and every time I notice it I seem to be in a hurry. Is there anything wrong with just pumping up my tire every morning?

Steely Dan

inflate the tube, fill the bathtub, fully submerge the tube in the water, then look for bubbles. it might take a while if it's a super tiny, really slow leak, but you'll find it eventually.

10 Wheels

I never saw a slow leak that fixed itself.
Put the aired up tube in water and look for tiny bubbles.

Kojak

It's very possible that you have a leak at the valve stem. At times a small piece of dirt/dust can slip down into the valve mechanism and not allow the valve to seat properly. Also, if the tube has been patched before, an old patch is another possible culprit.

As for any harm in just continuing to pump up the tire? Not really, but if it's a hole in the tube, the hole will eventually get bigger at which point you'll have to take the time to replace/fix the tube whether it's a good time or not. I prefer to do these things on my terms (in my house) than on the tubes terms (somewhere out on the road).

Andy_K 

That kind of leak can be a sign of either rim tape failure or something just barely poking through the tire. I'd probably take a cotton ball to the inside of the tire and the wheel. If it doesn't reveal anything, try a new tube and see how it goes. Then you can patch the old one at your leisure.

SouthFLpix

Those kind of leaks are difficult to diagnose. I recommend just going with a new tube.

Thomas_CAAD9

Tubes are cheap enough if you don't have a spare already just get a fresh one.

Not worth the potential hassle if it fails mid ride.

Can either toss it or fix at your leisure then

alan s 

I never patch tubes unless my spare has a hole and I'm on the road. I'll replace the tube as soon as possible if patched. They are inexpensive and easy to replace.

Nonetheless, if you have a hole, you need to identify the cause, because if something is embedded in the tire, the replacement tube will quickly get a hole. Soapy water on an inflated innertube will form a bubble pretty quickly. Put some dish soap on a soaking wet paper towel and wipe the tube.

Also, keep track of how the tire was installed, which will make finding the culprit much easier. Most people install the tire label at the valve stem for this reason.

pdlamb

Try room-temperature water with dishwashing liquid in it. Makes the bubbles show up just a little bit better.

You know it's going to get worse, and Murphy says it'll be at the worst possible time.

CB HI

For me, 90% of time, a slow leak like the OPs is caused by a michelin thorn (steel belted wire from car tire). Just replacing the tube would give you a new tube with a slow leak.

Note the position of the tube on the wheel, remove tube, find leak with water submersion, match leak location to tire and remove michelin thorn. Can also use the cotton ball to find the thron or glass, assuming the pointed part does not retract into the tire without the tube pressure.

I had a 1/2 inch michelin thorn Monday that went through the tire and was lodged in the tube when I removed the tube. Found the michelin thorn while sliding my hand over the tube trying to feel the leak. That was a first, but probably caused by the michelin thorn going through a patch in the tube that help hold the thorn.

TimmyT 

+1. The peace of mind is worth the few bucks for a new tube.

fuzz2050

It happened to me once, I swear. It was a really slow leak though (Think over the course of a week, not a day) so I never bothered to repair it; after all, you should be putting air into your tires at least once a week. After a couple of months of the deathly slow leak, it just stopped, and the tube held aid as well as any other.

To this day, I have no idea what happened, either to cause the leak, or to fix it.

Booger1

Inflate tube,put in tub of water,you'll find it,know matter how small.

You can keep pumping it up if you need the workout.

Kojak

See my post above on dirt in the valve. It's possible that this was your problem and eventually the dust/dirt was blown away during inflation.

mikeybikes

I'm surprised at all these folks suggesting a new tube. Almost all punctures can be patched. I can't recall the last time I bought a brand new tube. I just patch the ones I've got, or if I'm building something with a wheel size I don't have tubes for, I buy used ones from the co-op for $2, often already patched.

I have one tube that has, so far, 19 patches.

Kojak

I've always replaced tubes, even before I worked at Schwalbe and I'm glad to donate my old ones to the local co-op. I don't want to have to worry about whether my patch job was good or not. Using my current method, I still don't go through more than 2-4 tubes/year.

tarwheel 

Like others said, submerge the tube in water and you should find the leak. I recently used the last spare tube I had on hand so finally got around to repairing the pile of flatted tubes in my garage -- about 15 of them. As it turned out, about 5 of the tubes were OK and just got mixed up with the flats. However, 3 could not be repaired due to leaks at the base of the valves or holes so large that I wasn't comfortable using them anymore. The rest I patched and saved myself $50 or more. You guys must come from a different socio-economic strata than me if you think tubes are cheap -- most shops are charging close to $10 for new tubes these and $5 is a bargain basement price.

Kojak

I can justify the cost of tubes as I've easily spent less than $5.00 on fuel in the last 3 years for commuting, and the insurance bill for my bikes is -$0.00-. The only times I've driven is when I've had to pick up my son from school (twice I think). If I ever get to buy the Metrofiets box bike that I want, I'll be able to pick up my kids in that.

alan s 

I regularly find tubes for around $4 at Performance. You have to wait for sale prices and stock up. Decent quality for the money. I don't get that many flats to make it a major expense.

El Gigante

or buying a new bike!!

Wake

If it's a presta valve, check if it has a removable valve. There would be flats on the threaded part just below the thumb-nut. Tighten to finger-snug using pliers, 6" crescent, etc. on the flats. I do this on every tube that has the removable valve and find almost all of them can be tightened 1/2 turn. That's solved my problem with 20lb/day leaks.

rwp

You're my new hero. I've had a few that went to double digits but none with 19 patches. With all the goatsheads out here I'd be spending a couple hundred a year on tubes if I didn't patch them.

mikeybikes

I will admit, I rolled through a patch of the goatheads with only the front tire once. I pulled 9 out of the tire. I seriously considered replacing the tube. Fortunately, the co-op has an unlimited supply of rubber cement, sandpaper and patches.