Bicycle Mechanics - What on earth is causing my flats?

I've been getting a lot of flats lately, like 1 flat every 3 times I ride (only 8 mile rides). The most recent flat has made me wonder what is really going on... you see, this flat happened on my *first* ride, after putting on Armadillo tires (to prevent the flats). Since these were new tires, it was easy to check for glass in them. There was only one piece of glass in the whole tire, and it didn't even get to the inside. Now, this I find odd, but then I notice that this puncture (which was larger than any I've had before, it was about 1cm around when stretched), was located on the inside, that is, it should have been pressed against the rim.

You must be thinking that my rim spokes are exposed. They are not... there is not one "bulge", and I do have rim tipe all around. I checked the part of the rim where the puncture had been, and there was nothing there that was sharp. There are slight depressions though at each spoke (rather than bulges). But, again, they are covered and so are not sharp.

Is it possible that a tube,when fully inflated (it was at 125psi) may not be facing the right way? That is, when I put the inner tube in the tire, it is often crumpled up and twisted a bit, but I expect that to fix itself as I inflate it, no?

Please, someone give me the answer. I'm sick of changing flats in 20 degree (F) weather.

One day last summer I had 3 flats on the 27km ride to work. I have Armadillos too. The flats were on the inside of the tubes. The rim strip wasnt covering the holes over the spokes 100%, so the 105psi was enough to make the edge of the holes cut the tube. When I got home I put a file to the holes to round the edges, and was careful how the new rim strip lay. I havent had a flat since.

I too had multiple flat problems, and the culprit turned out to be "goathead" thorns. They are very small, but very sharp. They cut through my new Michelin Axial Carbon tires like nothing. So, I bought some flexible plastic tire liners from BikeNashbar. These are long plyable plastic strips that go inside your tire before you put the tube in. These strips ($5.95 for two) are virtually impenatrable by thorns or glass or whatever. Since putting them on, I have had 0 flat problems. They do add a little weight to your wheel, but I haven't noticed any performance difference.

It does sound as if your rim tape is moving or something to expose the spoke end. I personally have had this problem, in particular after I've pumped the tyres up to full pressure the night before.

Are you using a rubber rim tape or one of the tougher woven type?

Originally posted by trmcgeehan
I too had multiple flat problems, and the culprit turned out to be "goathead" thorns. They are very small, but very sharp. They cut through my new Michelin Axial Carbon tires like nothing. So, I bought some flexible plastic tire liners from BikeNashbar. These are long plyable plastic strips that go inside your tire before you put the tube in. These strips ($5.95 for two) are virtually impenatrable by thorns or glass or whatever. Since putting them on, I have had 0 flat problems. They do add a little weight to your wheel, but I haven't noticed any performance difference.

I've had the same problem, and put tape in the back. Since then the only flats I have had have been in the front wheel.

I'm gettting more tape for that this weekend.

Could the problem be that torsion on the tube when installing is tearing it.?

When installing a tube I always slightly inflate it so that it doesn't kink.

OK, now, the guy lives in Pennsylvania, so it's not goathead thorns.....

Here are a few things to look for:

Burrs on the rim surface, especially at the edge of the rim tape.

Burrs on a spoke nipple: it doesn't take much of a metal sliver to poke though the rim tape and puncture your tube.

Wires sticking out from the tyre bead: i've seen this happen on my own Armadillos. I'm betting this is what's happening.

Stray threads from the tyre belts sticking out on the inside: not likely here, since you mentioned that the punctures were on the inside, but this happens fairly often. Kevlar (or similar aramid fabric) is often quite abrasive. I've known several people that have had kevlar-belted tyres destroy their tubes, as ironic as that sounds.

Two points I will make. One is to slightly fill the tube with air so that it holds it's shape so that you don't put it in twisted. Twisted is bad and should not be done. Second, make sure you have the right size(width) rim tape for your rims.

Oh, and third, get Velox cloth rim tape and make sure the bead of the tire is not pinching the tube when you put the last part of the tire onto the rim after changing a flat.

Is the puncture in the same place every time? If so, check for something sharp inside the tire at that area and make sure to pump up adequately so you don't pinch flat constantly just in case that is the problem.

straighten the inner tube before you pump!

also, if your inner tube is a size or more too small for the tyre, then a friction build up will cause it to puncture.
When the two surfaces rub together.

If possible, avoid using tyre levers when installing the tyre. (Do as I say, not as I do, since I absolutely have to use tyre levers to put Conti Ultra-2000s on my Campag. Omega rims.) The other suggestions in this thread are quite sound.

And don't forget to use talc powder on your new tube before installing it in the tire. This cuts down on pinching. I always carry a new tube in a ziplock bag with plenty of talc in it.

Its been said before and I'll say it again. Inflate the tube partially when putting it in so that it will hold it's shape. It's hard to diagnose if it's the rim or the tire over the internet, without seeing it, but the one obvious problem is that the tube needs to be straight and not crunched up when you are installing it. I work at a B-shop and I have changed more than my share of tubes and tires for a lifetime, and one of the mistakes I made when I started was cramming the tube in. It resulted in many brand new unridden tubes exploding VERY LOUDLY by my ears. Good luck.

sounds like you might be pinching the tube with the tire tool. if you don't have a bit of air in the tube so that it holds its shape, it has a tendency to get lodged between the tire and rim. when you pry the last bit of tire over the rim you may be pinching the tube.

here's how to avoid it:

1) put a small bit of air in the tube so that it holds its shape.
2) practice using only your hands (no tools) to remount the tire.
3) you can also pinch the tube when taking OFF the tire. try to stick the tire removal tool only far enough in that it snags the tire, not so far in that it reaches the tube.

it might be a good idea to visit your local bike shop and let them watch your tire-changing techniques. they may be able to pinpoint your problem.

i use armadillo tires and i hardly ever flat.

What on earth is causing my flats?

Loss of air in your tires.:p (jk)

I went through the same prob for a while but with sew-ups. Finnaly figured out I can not run them on hot days because the combination of my weight, speed and heat the glue would soften letting the tire slide and therefore tear the valve stem.

Slainte:beer: