MNBiker

I have a stock Specialized brand tube in my 700cx28 Marathon Plus front tire. I think the tube is about 3 or 4 months old. The air pressure was topped off to 100 psi yesterday (while sitting in a 50 degree F. garage) but I didn't add any more air for today's commute so I don't think it was overinflated.

I had been at work for about 2-1/2 hours when suddenly there was a loud BOOM from the exploding tube. I figured out what caused it quickly enough, while waiting for my ears to quit ringing and while getting over my shell shock. I reassured the woman down the hall that the noise wasn't from a gun.

When I examined the tire it was off the rim most of the way around on one side. The tube itself has a foot long split following the circumference and starting about an inch away from the valve, and it runs along the side. I didn't find any sharp items in the tire.

A very similar thing happened a couple of months ago where the rear tube blew while sitting in my office.

I am wondering what causes this and what I can do to avoid the same thing happening in the future.
Ideas for causes:
1. The Specialized tubes are inferior.
2. 100 psi inflation in cool weather expands too much inside and blows out the tube because of over inflation.
3. I have installed the tube/tire improperly (months ago) resulting in the tube being twisted up inside the tire and susceptible to blowouts because of internal friction or rubbing after inflation. My boss says I should add talcum powder when installing new tubes.
4. There is something sharp in the tire/rim causing the blowout.
5. The Marathon Plus slipped off the rim (poor mounting?) and this caused the tube to be pinched and blow out.

I really have no idea of the cause. I don't think it was caused by numbers 2 or 4. Any ideas?

buckstoy

To me it sounds like the tire was not well seated on the rim. It sounds like the tire came unseated and the inflated tube came out, this to me would explain the long tear in the tube.

Jason

oakback

Can a tube really pop from pressure if it's contained by the tire? I figured the tire would have to fly off the rim as well if it was indeed from too much pressure.

AdamD

Yes. I used to live in an area that got hot in the summer. If I left my bike in my car all day I had to deflate the tires a bit or they would pop once in a while.

StanSeven

Either the bead isn't seated right or you have part of the tube outside the tire. Both can cause that but the other things cited won't. Blowouts like that are from the tube suddently expanding. Holes or a tube failure inside the mounted tire just causes flats

MNBiker

I am beginning to think that maybe the bead wasn't seated right, as StanSeven suggested. I know that Marathon Pluses are a little tricky to seat correctly, both from what I have heard and what I've experienced. I will try to be more careful when mounting them.

I am open to any other ideas with reasons to back them up. Thanks for all the suggestions.

StanSeven

Sometimes they come unseated because a small piece of the tube is caught. Mount the tire with a little bit of air in the tube, and check all the tire all round on both sides before inflating. If you see any tube under the tire at all, adjust the tire until the tube is completely inside.

pathdoc

Bad rim tape is often to blame. Check rim closely to ensure all sharp edges are covered.

obie33

Happened to me once, but I was in a hotel room in the middle of the night. Happened to be at a LEO school for tactical entry. Needless to say I almost put a dozen or so rounds into my Cannondale from my handgun! That would have been a real shame....

dcrowell

It's been a weird day for blowouts.

I had a blowout on my ride into work. The tire sidewall was damaged by debris, and the tube squeezed out, and BLAM! I bought a new tire and tube at a LBS and continued onto work.

Another commuter here at work has his cruiser bike parked outside his office. We're standing around talking, and BLAM! I thought it was my bike at first, then we checked his. His rear tube was blown, and the tire unseated, but undamaged.

He had been riding on a low tire for a few days (he's a real Fred), and aired up this morning at a gas station. I guess the tire was no longer seated properly from riding under-inflated.

I had him take his rear wheel to the same bike shop. He had no idea how to change a tube.

CB HI

The tire came unseated, likely from not being properly seated when installed, in combination with the pressure increase from bringing the bike inside to a warm area.

Double check both your tires are properly seated and try running your tire pressure (when cold) at 90 psi. See if that solves your problem. If not, post back with an update.

FlashBazbo

I've had repeated blowouts on my 29er. They started after rim damage caused by road debris -- high speed incident involving a broken beer bottle followed immediately by a major road crater. There isn't much of a kink in the rim, but there's a kink. Nothing sharp. Just a very slight kink.

Once, a tube lasted as much as 15 miles. Most of the time, the tubes blow out with the bike sitting in the garage.

Solution? New rim. Bummer.

Metricoclock

yeah temp difference from 50f to 70f isn't going to raise the tube to a point of blow out, but keep that in mind though this winter, 100psi below freezing will def expand on its way to 70f.
I put my bike outside in the back yard this morning to acclimate the pressure before bringing them up to my reg pressure, was 65f inside the house, 47f outside.

Big_e

If the tire isn't seated properly, the tire and tube will fight for space, especially around the tube nozzle where it is sometimes the hardest to seat the tire properly. When airing up your tire, before there is too much air (2 or 3 pumps), Push the tube nozzle into the tire. This will give the tire area around the nozzle priority to being seated properly. Make sure the tire is completely seated then continue to air to recommended pressure. Those tubes are loud ain't they!
Ernest

JR97

For what it's worth, I had 2 Specialized tubes split right down the seam. I got about 20 miles out of each tube. Conversly, I have a pair of kenda tubes and a pair of cheapo pyramid tubes that have multiple patches that have hundreds of miles on them and seem to work just fine until the next goat head or puncture. (I need puncture resistent tires, damnit.)

n4zou

Keep the office cat away from your bike.

ActionJeans

Nope, good tubes.
Nope.
I don't think talc is necessary, but you should always slightly pressurize tubes before mounting to tire. It does sound like it might be a pinch flat

No. That would just cause it to be flat, not "esplode"
Wouldn't you be able to tell this by looking?

I'm gonna go with improper tube installment (read, inflate tube slightly, meaning, with your mouth (insert joke here)), and install; OR crappy rim tape on the rims that is leaving a tiny gap in one of the spoke holes, and is putting just enough pressure to go "ker-blammo".

So when you have your tire off, check for rim tape issues, (if it's not cloth, it's crap, so replace it with cloth, and make sure it's wide enough), and when replacing the tube, remember my word. I mean words.

dobber

The tube can not exploded from pressure while inside the tire. It can only explode once it's been released from confinement.

Most likely the OP's tire was not seated properly or in some way worked itself loose. Schwalbe tires can be a bit hinky, I've had trouble getting the to seat.

Grim

coughing <under breath: "bull****">.

Had one pop on my bike sitting in the foyer and hadn't been ridden in 30 or so hours. Tire was still on the rim and the air was escaping around the stem. Scared the hell out of us. Though we had a water line in the laundry room behind the bike give it up.

Tube was old and it let go where it was stretched over a nipple on cheap rubber rim tape. No sharp points could be found just obvious deformation of the tube at every nipple. Swapped the tube and used velox fabric rim tape to replace the rubber.

HOV

Damn you, office cat!

psoshul

Hey I have the same problem, mine were rated to 50PSI, I filled to like 45-48, rode the bike no problem, then about 1:30 am... BOOM!!! This is happened now twice on my bike in the last year, and then also twice on my fiances mt. bike as well...

I'm sorry to those who say temperature can't cause this I think they are wrong... If it was pinched or improperly installed it wouldn't happen by itself after hours of sitting. I did this google search and found this article, primarily to confirm to myself that this was the case. I actually also keep our bikes, near our furnace room, with the concrete floor (cold) and the furnace air (hot) I assume this is the culprit. I'm going to move the bikes, and keep the tubes a minimum of 5PSI under the recommended.

I'd love to buy the tubeless setup, but will not go that route unless I purchase a more robust mt. bike.

(FYI, my sons bike as well, it was a little 12" 2 wheeler, sat one day after I filled to exact pressure, on the porch in the sun, it was a cold day, but the sun was hitting that black tire and black rim, BOOM... that little thing went too.

HardyWeinberg

Is there any chance you're using a presta valve tube in a schrader-drilled rim? The tube can get cut on the valve hole and blow.

JReade

I was doing a big beer ride in Michigan, and we aired our tires up the night before, test rode everything, said "alright, sounds good!" then went to bed. Next morning, it was probably 50 degrees out, we aired the tires up to 110 psi, and left them in the shade while we went and had a quick breakfast. Came back and one of the group says "Oh man, I've got a flat!". Temps were pushing 70 degrees and the flat tire was in the sun now. Saw the tire blown off the rim, thought maybe it was just ridden a bit with the flat and it was off the bead. Replaced the tube, aired it back up, and no more than 20 minutes fixing it and putting the bike in the sun, the front tire/tube blew clean off the rim.

David Bierbaum

I didn't have luck with Specialized tubes. They seem to be designed for weight-saving and rolling resistance improvement, but they get leaks if you so much as look at them the wrong way.

Has anyone done the simple experiment of inflating their tire to a certain pressure, putting their bike/tires in sunlight for 10 minutes, then checking the pressure again? Since PV=nRT, I'd imagine that high-pressure narrow tires/tubes could suffer large pressure changes when the tire heats up in direct sunlight.

fietsbob

Odds are; installation poorly done, incomplete.. tire blew off the rim, because the tube was not entirely between the beads,
tongue of tube was trapped under the bead of the tire.. inflated, it pushed the tire off.

Other situations; If sidewall burst out a tear, and the bead stayed in place, you would find the tear.
blew tube as a side-effect. it was not an innertube issue , ..

Tube most likely just a fast leak but no bang, Then you would see the problem when you replaced the tube.
Seam , stem leak, or imbedded stuff wearing a puncture in after riding a while..
Mr. Tuffy band end abrasion do their own flat making..