So i just recently started commuting with my road bike. Been about 2 weeks now but I have a consistent problem.

My back tire had a flat on the first day, good times. So I had the tube replaced at a shop cause I was close and it was most convenient. After that my back tire has been flat every time between rides. i can inflate it and ride to or from work with no issue but the next time I go to ride it is completely flat.

I took out the tube doing this and checked for leaks. Under water i found no source of a leak. So I replaced the tube and the new tube is doing the same exact thing.


Any help? Ideas?

Thanks

Did you put a lot of air in the tubes? The tube will swell quite large compared to it's size in the tire. I pump mine up to about 2" or so in diameter. Then fill a bucket with about 4" of water and put a section of the tube under the water and check for leaks. Do this all around the tube. You should soon find your hole.

It sounds as though there might be something sharp in either your tyre (use your fingers to do a touch test along the whole inside of the tyre) or inside the rim (either rim tape has split or there's a burr on the rim - again touch test).

1. Put a few inches of water in the bathtub with a little soap in it, (dishwashing liquid or baby shampoo will work well).
2. Fill up the tube with a good amount of pressure. Not so much that you can't bend it, but you need to give the rubber a little stretch to find some pin-prick leaks.
3. Slowly inspect the tube in sections under the water and just above the water line, (you'll be rotating it as you check it over). The soap will foam up at the site of the leak.
4. Check the valve in the soapy water also. Sometimes grit will get into it and keep it from sealing.
5. *****INSPECT THE TIRE. Repeated flats often indicate a compromised casing. Usually not to the extent that it needs replacing, but a shard of glass or metal could be protruding through the rubber. Removal of the foreign offender is likely all that is needed. Use a cotton ball and run it around the inside of the tire. The fibers will hang up an any sharp objects sticking through the tire. You can also run your fingers around the inside of the tire, but the bloody digits just end up making it harder to get your wheel reassembled, after you've patched the tube.

Oops. You guys beat me to it.

And as markhr says, check the rim and rim tape for pricklies.

To find the embedded debris, use a cotton ball around the inside of the tire and watch for fibers that snag on the pokey bit. You can use your hand also but, as mentioned elsewhere, be careful. You might try aligning the tire with the valve stem (the label is a good indicator) so that you put the wheel back together the same way each time. Mark the tube with a permanent marker with the side and direction so that it goes back together the same way all the time. If you end up with multiple punctures in the same spot, you've found a hidden pokey

Rim tape, rim tape, rim tape. Check those 3 things and see how it goes.

I second the cotton ball test...not as messy as a finger can be.

Why I had never come across this tips before I got my finger pricked the last time I had a puncture...

I have a slow leak too that just looking for bubbles from the tube under water has not yet revealed. Maybe I just need to find something larger than the bathroom sink and immerse the whole tube for a bit of time. My finger hasn't been snagged on anything inside the tire yet, at least.

I hate to say it but;
Get a New Tube.

Good ideas, but I've found a few no-see-ums flat makers in tires before that couldn't readily be felt and only appeared as the tire casing flexed. Could be a small wedge shaped piece of glass, or a very small wire, or a skinny thorn needle.

Buy a new tube, then before you install the new tube take out your old tube and mark it so you know how it came out. Then take the old tube and with it outside the tire greatly overinflate it, like to where you get a bulge in it (you're not going to re-use it anyway at this point). You should now have enough pressure in the tube to let even the smallest leak show where it is. You can now use either the water trick, or place it up next to your ear and cheek to feel for any air escaping. When you find the leak then align the leaky tube up with the tire and rim to find the mysterious leak maker.

Also, when you say flat, how flat is flat? Does it just loose 20Lbs of pressure so it looks flat while you are sitting on the bike, or does it loose most of the air so it looks flat with just the weight of the bike sitting on it?

Blow the tube up bigger. Small leaks may not show up until the tube has be stretched significantly. 1.5 to 2 times normal size works for me. Work the tube around in a tub of water or sink in about 6" sections. Wipe the little bubbles off and see if they come back.

Thanks. I think I will keep pumping it up through the week (only just one more time if past results indicate future performance) and devote the time I would have spent replacing the tube this weekend to really *inspecting* the old one for wherever that leak must be.

Lots of us have had this problem before. As stated by others, I always:

1. Replace the tube, but also find the hole in the old one and patch it to use as a spare.
2. Replace your rim-tape. Cheap and easy fix for lots of flats.
3. Scrub the inside of your tire with your fingernails, to see if you can find anything sharp in there. Even if you don't, it may be a good idea to really scrub the inside out with a nylon scrubby-pad to knock off any sharp things you missed.

It is what I do, when I start having multiple flats, and it has not failed yet.

Have fun out there!

well thanks guys. it indeed was rim tape after all.

An easy way to do this is to put the label on the tire right by the valve stem. I always put the front of the label against the valve stem. That way, I know where the tube was sitting relative to the tire without having to actually mark anything.

That cotton-ball tip is great. I will have to try that trick next time I can't locate what's causing the problem.

I see rim tape seems to have been the culprit. One source of slow leaks I have had is a Schrader valve core being just a small part of a turn loose in the stem. Some leaks I have had are so slow that the bubble test under water does not show anything. I also gave up on tire liners because they caused more flats than they prevented. I put Slime in my tubes to protect against small leaks, especially from thorns.

Well, I was going to work on it this weekend, but my slow leak sped up so I decided to fix it before heading off on the longer leg of my am commute today. Was weird, I found the leak, it was a ~1mm sq abrasion/thinning of the tube, perfectly visible. There was a corresponding puncture in the tire but no sharp culprit, so hopefully that's taken care of now.

Last time I had a slow leak, as I unscrewed the presta top nut I actually unscrewed the entire core. I suspect a loose valve core caused the loss of air, rather than a small puncture since I couldn't find a leak.

Must have been a ZOMBIE flat! It's dead now and all is well...

Happy Halloween!

Pumping up the tube to twice its diameter is a good idea to locate punctures as it also stretches the hole and makes locating it a lot easier. However the 2 or 3 psi involved may not be enough to effectively test the valve for a leak.

I recently had such a problem so tested with tyre and tube mounted and pumped up to 80 psi. I immersed the part of the rim with the valve in water and sure enough there was air escaping from the valve. At 27 psi this stopped - which I guess is why my tyre would go soft but not flat when left for a few days.

Cheers, Adrian

Double Zombie! Awesome.