aem0512

I put new tubes on my road bike and began to air them up to the recommended pressure. Before I even got to the minimum pressure (75 psi) it popped! Then I noticed the other tube was doing the same thing. It seems like there is some type of bottleneck going on near the valve. The tube gets huge right near the valve, but doesn't spread well throughout the rest of the tube. It ends up pulling my tire off the rim as I air it up! (bell 27 x 1/4-3/8 road bike tubes)

Is this normal for tubes? Am I just doing something wrong here? They aren't twisted inside the tire or anything.

FBinNY 

Don't take this personally, but it's not the tubes, it's you.

Tubes are simply rubber bladders with no mechanical strength. When aired up they inflate to fill all available space within the tire and rim, and if not constrained by the tire will inflate to bursting at about 10psi or less.

I don't know what technique you used when mounting, but I suspect you probably trapped a bit of tube under the edge of the tire, so when inflated the tube lifted the tire and bubbled out underneath.

Here's a few hints to avoid a repeat performance.

Start by putting some air into the tube before installing. Just enough to move it from a flat to round shape. It's much easier to stuff the tube up into the tire and reduces the chance of trapping it under the tire.

Before levering the tire over, nake sure the tube is well into the tire and above the rim. The tire should be laying flat against the rim all the way around.

When you've finished mounting the tire, push the valve deep into the tire, so it drags the tube up with it. This is important because the tube is a bit thicker near the valve, and the valve itself reduces the available space between the bottom edges of the tire. That's why most seating problems, and blow offs happen near the valve.

After pushing the valve in, gently pull it back out to make sure it's all the way out with the tube laying on top of the tire.

Inflate to only 20-30psi and spin the wheel watching the molded lines to amke sure the tire is evenly deep within the rim all the way around, and on both sides. If necessary, deflate and massage the tire around and try again. Once it passes, inflate to full pressure, and you should be OK.

Al1943

I agree that the failures were more likely problems with installation but, on the other hand, I have seen tubes that were defective when brand new out of the box. If you have any more of the same type of tube check for leaks before installing. Put in some air and hold under water.

Bat56

World's skinniest tubes! Thems is some small tires!

For real though, figure out the size of the tire and the size of the tube and get back to us.

I suspect that you are using a much too small tube in a much too large tire.

Example: If I put a 700 x 23 tube in a 700 x 40 tire, it does what you are describing.

FBinNY 

Yes, there are defective tubes from time to time, and it could be too narrow a tube, though I suspect that the size was simply typed in wrong.

But no defective or undersized tube would lift a tire off the rim, as described by the OP. Either the tire is defective, or damaged, or it's a mounting issue. Blaming the tube only delays the OP from addressing the true cause of his problem.

My suggestion is that he go to a local shop and let someone mount the next tube, and maybe also show him how while they're at it.

aem0512

I used Bell 27" road bike tires (says 27 x 1 1/4...forgot the 1 earlier before the 1/4! sorry) and Bell RideOn Universal Tubes 27" that fit 1-1/4" - 1-3/8" width range.

My rims are stamped 27" x 1 1/4 ".

And I really think you might be right about them being seated incorrectly. It was my first time to do this (obviously) and I noticed from the start that the pressure near the valve was pushing my tire higher than the rest of the circumference. But I still think these tubes might be a little wonky...it's probably just me. I tried to attach a photo, but it won't work at the moment. The part of the tube near the valve gets truly massive before distributing the air to the rest of the tube.

If it helps, the only thing I notice is strange about my rims is that the hole for the valve is really snug. I had to tap the valve out with a mallet.

aem0512

Oh, and the tires are new also. I'm restoring my grandmother's old road bike...thought it was ready to ride until this little tube blunder.

P.S. I am a 'she' FBinNY I'm sure the rest of the readers of this thread will now blame my gender for my tire changing ignorance. Fine by me.

aem0512

P.S.S. It was my granddad who helped me seat them anyway lol.

FBinNY 

I must be psychic, able to know it was gender related and .... before you gave us this tidbit.

Seriously, inexperience isn't a sin, nor is it gender related. No one, male or female is born with this knowledge, and experience usually means that the common mistakes are behind you, and you get to move on to newer, more exotic mistakes.

To the OP, many local dealers off basic repair classes including changing tires, and making the basic adjustments. The cost is usually very low, or free. These can be very helpful as they can show some little tricks that are hard to explain with text only.

10 Wheels

I have had 5 defective New Tubes as well as doing some improper installations.

I ride with some women that can change a flat tire quicker than a man change a baby's diaper.