PatrickGSR94

I've had my Felt road bike for 2 weeks now, and yesterday had a random spontaneous blowout. First blowout ever that I can recall, and I wasn't even riding the bike!

The fact is I had not added air to the 700x25c tires since the bike left the shop 2 weeks ago. Saturday I rode 21 miles, no problems at all. Then Sunday I was getting ready to ride, about to load up the bike in the car. Bike frame was upside down in the garage, both wheels were off the bike, sitting over to the side. I topped off both tires using my shop air compressor with regulator set to 110 PSI. I just stuck the air chuck on the stem of both wheels until the pressure equalizes, then release.

So I did that to both tires, had them sitting over against the wall, while I was tending to the bike frame. Suddenly (about 5-10 minutes after topping off the tires) I heard a PSSSSSHHHhhhhhh for about 2 seconds. Went over and found the front tire empty. Took the tire off and removed the tube, and found this hole in the tube, facing the rim, about 1/2" away from the valve stem. I looked at the rim tape and also inside the surface of the tire and found nothing apparent that could have caused that hole. I stuck a self-adhesive patch on and tried to pump up the tire, but the air leaked right out through the patch straight away.

I ended up going to the LBS and the mech there said it's kind of an odd place for that to happen, and not really easy to patch when it's that close to the valve stem. So I just got a new tube and was on my way. Sort of glad anyway because I replaced the original tube with a Bontrager tube with threaded valve stem and nut that keeps the stem from getting pushed into the tire when attaching the pump head or air chuck. Much better design IMHO.

In the pic showing the rim tape, the hole was facing the rim tape just LEFT of the valve hole. The guy at the LBS put a piece of tape over that seam in the rim tape to smooth that transition, but that's not where the hole was, so that seam definitely didn't cause it. Any idea why this might have happened?

*edit* Also I did check and the hole in the tube was NOT where the spoke end/hole is located. So a spoke didn't do it, either.

merlinextraligh

You tore the tube when you pulled the compressor hose off the valve stem.

The tube failed right where the rubber around the valve meets the rest of the tube. Tubes occassionally fail there. It may well have been defective, and just enough of a tug caused it to fail.

If the valve isn't in straight and is getting pulled around, it can cause this. Also you don't want to tug the valve sideways with the pump, but likely just a tube with a weak spot and some random bad luck.

Put a new tube in and don't worry about, unless it becomes a repeat problem.

tagaproject6

Looks like a manufacturing defect where the reinforcing material that bonds the valve to the tube failed.

LowCel 

That's a flat, not a blowout. Unless you hear a big BOOOOOM it is just a flat. As far as the rest goes, Merlin pretty much covered it.

PatrickGSR94

Just seems odd that it didn't let the air out until 5 or 10 minutes after filling it, though.

And it's not like any tugging was required to get the air chuck off the stem. I usually just press it on there and the air pressure itself will push it off when I left off the pressure of my hand. My floor pump head requires more of a "tug" to get off the valve stem than the air chuck does.

merlinextraligh

^ which gets back to the tube likely being defective. Didn't mean to imply you did anything wrong. It was likely just enough force to break the camel's back.

PatrickGSR94

In my mind, a sudden and complete loss of pressure is a blowout. The opposite of a blowout is a slower leak. Either can cause a flat.

PatrickGSR94

Yeah I don't really care, since I prefer the threaded stems anyway. I might actually change the other one before it flats, I dunno. I was just seeing if there's anything that can prevent something like this from happening in the future, which apparently there is not. Luck of the draw I guess.

I might go ahead and change the rear tire's tube and then carry the rear tire's original tube as a spare.

LowCel 

Just change the rear when you flat. There is probably a larger risk of pinching the new tube when you install it than having two defective tubes at once.

PatrickGSR94

Yeah but I hate that non-threaded valve stem.

gadabout007

I've seen several flats and leaks where the valve stem meets the tube due to folks over tightening the nuts included with some tubes. Personally I just chuck them out with the valve cover when I use install a tube. Maybe it's just me, but I find that the threaded valves rattle more than the smooth valves when using deep dish wheels.

PatrickGSR94

Interesting, I have the threaded valve stems with nuts on both tires of the KHS, and now one on the Felt, and I've never had problems with them. I always check and snug them finger tight before putting the air chuck on it, but that's it. Only finger tight, no tools used. And if they're snugged down I wouldn't think they would be able to rattle at all.

ericm979

You don't need valve stem nuts. They just slow down tube changes.

LowCel 

I never use the nuts or valve stem covers either. Just an extra step when changing a flat and pumping up tires.

gadabout007

walk through any of the bike shops here in Toronto that carry entry level bikes and you'll find reflectors, valve covers and nuts as well as the disk that keeps the chain out of your spokes on every bike.

walk into any of the high end shops here no disks, reflectors, valve covers, or valve nuts.

PatrickGSR94

The valve covers on Presta valves are only there to keep the valve from puncturing the tube while it's in the box. They're not needed to keep dirt out of the valve like with Schraeders. I don't use those, either.

And I put my air chuck on the valve way more often than I change a tube, so I prefer having the nuts on there thanks. It's like 10 extra seconds getting it on and off. I'm not racing here, folks.

jester666

So one thing I have to put in here, just out of experience - Road bikes loose pressure really fast.

If you are running..say 110psi, within 1 or 2 days the pressure will drop 10-15Psi.
As the pressure gets lower this loss slows down, but if your bike left the store at..say 100, I would not be surprised if you were riding at 50-60psi 2 weeks later.

It's normal, but with a smaller foot print of the road tire proper pressure is that much more important.

Good air pressure is your first line of defence against flats.
Softer tire tends to envelop and absorb the object.
Harder tire is more likely to deflect the same object.

I recommend getting a good quality floor pump, and checking your pressure before every ride. Even if you ride every day.


p.s. just looked at your pictures.
and read your description.
Most likely either the tube had a flaw, or it got damaged slightly from low pressure allowing for some strain and movement at that spot.

I have had stuff like that happen.

Sometimes at the shop I worked in we would have a spontaneous 'explosion' of a tube from a bike just hanging on the rack.
I kid you not. Customer's bike hanging for a few days, waiting to be picked up, nobody touching it, then out of the blue one of the tubes blows.

Weird stuff, but I guess not all tubes are perfect, and some have damage which does not go all the way through, but is enough to be a 'ticking time bomb'

kaliayev

Thanks for the input. Glad to know bike snobs are in Canada.

10 Wheels

This is a Blow Out:



Please air up your tires before Every Ride.

Commodus

This is a pretty epic thread considering it was started by a flat.

Machka 

LowCel is right ... a blowout includes a very, very, very loud BOOOOOOM!!

First time it happened to me, I was riding and it sounded like a gunshot right underneath me.

Second time it happened, I had just got in from a cold ride and brought my bicycle into a warm apartment. About 15 minutes later there was a BANG that had me and the cats clinging to the ceiling.

PatrickGSR94

Now that's funny right there

DannoXYZ 

Most likely the tube at the stem area wasn't fully seated into the tyre. This causes some of the tube to be lifted off the rim and it has to squeeze round the bead of the tyre to expand. This ends up stretching the material thin enough that it separates from the stem or opens up a hole.

To prevent this, don't start & stop mounting the tyre at the stem. And when you're done, push the stem as far into the rim/tyre as possible. You should be able to see a bump from the inner-end of the stem pushing outwards on the tyre-tread. This makes sure that the tube isn't caught between the tyre and rim.

banerjek

Or a friggin' shotgun blast. Anyone who counts something as a blowout that has no BOOM that leaves you with ringing ears most likely has not experienced one yet.

The critical difference between a blowout and a catastrophic flat resulting from cutting down a tire or whatever is that there is an explosion (hence the name). A huge cut might make all the air leak out in a fraction of a second, but it's not the same thing.

PatrickGSR94

Okay no, I have not experienced a blowout of that nature. I was just using the term "blowout" as a generic term meaning sudden and complete loss of air, whether it pertains to bikes, cars, motorcycles, or a wheelbarrow. Like you roll over something sharp in your car that make the tire suddenly go flat - blowout, vs. having a nail in the tire creating a slow leak.