Moflip78

hello, i have a giant roam1 with stock wheels/tires...i noticed this has been happening more often lately. no air after 2 days.

now i also noticed, when i ride on smooth surface, the rear or "I" feel like Im bouncing every rotation...like I'm driving through a crack (dip) on the road every 5 yards. i don't see anything visibly wrong with the wheel.

hamster

It's either a tiny hole in the tube (though I'd expect even a tiny hole to flat faster than 2 days), or a loose valve.

Either way, the easiest solution is to replace the tube. Could also take care of the second problem.

jimc101

Would find the source of the leak when replacing the tube, or you will be doing it all over again in 2 days time. Also, a good opportunity to learn how to patch tubes, as this is cheaper than replacing long term.

hamster

Well, yeah, in case the leak is because of something stuck in the tire, it's a good idea to find it.

In my experience, 80% of leaks are caused by poor manufacturing (leaks along the seam) and patching those is a waste of time, the tube would just come apart elsewhere.

Retro Grouch 

You're kidding, right? I've been riding and repairing bikes since the 60's and I've NEVER encountered a leaky inner tube that I could attribute to poor manufacturing.

10 Wheels

I have had three different brands that were defective.

Retro Grouch 

I can believe individual failures, but 80%?

10 Wheels

One was five tubes..The others were three tubes. They were all bad.

Retro Grouch 

That's 11 tubes. How many good ones have you gone through during that time? I'll bet it's more than 3.

10 Wheels

They were all bought NEW.

Retro Grouch 

OK, so you've had some failures. Other people say so too so I assume there is a failure rate. I'm trying to get a handle on what that rate is and you're dodging the question. I don't think that the failure rate is 80% or even 8%. Frankly, I doubt it's 0.8%, but it might be.

cny-bikeman

Agreed. Unless one has come across a particularly bad run from a particularly bad manufacturer tube defects at the seam are exceedingly rare. The only unfortunate exception lately is at the juncture of presta valve and tube.

Bill Kapaun

I had a Giant branded Schraeder valve tube that blistered on the valve stem outside the rim.
This was a skinny tube on 622-25 tires pumped @ 110.

10 Wheels

100 % on the new ones.

Retro Grouch 

OK. Now I don't believe you at all.

10 Wheels

You need to get out more in The Real World of bike riding.

hamster

Let me put it this way. More than 80% of all inner tubes have seams. The primary mode of failure of such an inner tube is bursting along the seam after a sufficiently strong impact, e.g. against a piece of gravel.

Yan 

1. If you really went through five new tubes during a change before you found one that held air, I would consider the possibility that there is an issue with your tire mounting technique, and that you are putting holes in your tubes with your levers. I have gone through a lot of tubes over the years and have never had a single new one fail at a seam, only at the valve. Perhaps you bought them all at the same time and got a bad patch, but you say there was another occasion where you went through three new tubes. I have worked in a shop and find it quite hard to believe that you have had such bad luck.
2. Regarding your exchange with Retro Grouch, obviously the notion of statistics means something different to you as compared to most people. That's ok, people think in different ways, but I suggest you stick to adjectives in the future.

Wilfred Laurier

+1

also
the idea that most flats
are caused by a seam bursting
is complete nonsense

AnkleWork

I've never seen an innertube fail at a seam. Can you describe these seams? Do they run around the length of the tube?

RR3

Use seamless latex tubes. (Check the inside of your tire with a cotton ball.....might be a small thorn or glass)

Have not had a flat in over 5,000 miles.

Only half the tire pressure goes in 2 days but that is the price one pays for riding latex tubes in exchange for lower rolling resistence, more comfort, and better puncture resistence.

Whiteknight

In 10 years and 30,000 miles with our bikes I had two tubes fail where the schrader valve base pad joined the body of the tubes. When the tubes were cured they were inflated while being cured. For some reason the rubber became paper thin around the big base of the valve.
I have also had two fail when the rubber did not get a good bond to the brass schrader valve stem.

Considering the number of tubes we have gone through in 10 years I can't get too excited about new tube manufacturing defects.

Murray Missile 

Check your valve stem, you can try airing the tire to full pressure and spraying a little soapy water on it. I've had several slow leaks that turned out to be a valve stem that wasn't fully seated, it doesn't take much. In most cases I could not feel any movement when I tightened it but afterward the loss of pressure stopped. That's on Schrader and Presta both. I did have one Schrader tube that had a bad valve stem core, stuck one out of an old tube in it and the leak stopped.