rumrunn6

several weeks ago I broke a spoke & had a shop, a good one, replace the spoke. picked it up & noticed the tire wasn't fully inflated meaning inflated but not hard but then didn't give it a 2nd thought. flash forward to last night. going to see daughter in VT w Wifey & plan to bike the lake trail trail up there. get the rack on the hitch, the girls bikes on the hitch rack & mount my rear wheel. I inflate straight to 110 lbs & about 2 seconds later BANG! no desire to troubleshoot cuz football soon & more to get ready. throw son's bike on the rack, I can deal with it as my backup (forgetting I recently tuned up my own backup bike DOH!)

anyway - thinking this was a pinch flat cuz when they replaced the spoke they worked on it from the inside? & rushed the reinstall of the tube/tire. when I get back next week I plan to take everything off & fully inspect & redo with a new tube

dsbrantjr

I'll bet that your tube was not fully inside the tire and was protruding past the bead when you inflated it.

Retro Grouch 

Yup, almost surely operator error. That's the result of pinching a portion of the inner tube under the tire bead. It happens.

10 Wheels

I once did that twice in a row with new wheels,tires and tubes in my office.

Wife thought I was testing my gun.

leob1

What those other guys said.
My daughter also live in Burlington, we take our bikes every time we visit. Love the island line trail.

fietsbob

Once you finish refitting the tire , go around the wheel squeezing the bead inward

to make sure the tube is just, between the tire beads , not under , so wont push the tire off the rim.

like it < i guess> Did.





./.

Spoonrobot 

If the tire is still intact, you probably pinched the tube as mentioned above.

If the tire is damaged and the bead/tread are separated, it was probably a defective tire bead. If it's worth your time you can contact the company and request a replacement for a manufacturing error.

FBinNY 

This wasn't a pinch flat as much as the result of a poorly seated tire that was pushed beyond the edge of the rim.

So, like the others here, I'd call it an operator error, but the culprit is like not the OP, but a rushed and careless shop mechanic who sloppily mounted the tire after replacing the spoke.

The tire didn't blow in the shop because he didn't inflate it to full pressure. Unfortunately this the kind of thing that can never be proven either way, so it's the OPs loss to eat.

Mounting errors can be avoided, or made very rare by using the reference line molded into tires. It's a line that should be visible slightly beyond the rim's edge. Mount a tire, inflate to 20-30psi (firm and fully shaped out, but not full pressure), and spin the wheel watching the reference line. It should be at a uniform distance all the way around. If it's higher in places, that's where it the tire is lifting out of position.

However, low areas are equally important and often more so. The tire's bead has a smaller diameter and cannot stretch over the rim. Tires can only be mounter of blow off, if the bead is dislocated and lower in some areas to generate the slack so they can be higher in others. So just as this principle is how you mount a tire, it's how tires blow off.

BTW - pinch flats don't go bang, they hiss. If a tire goes Bang, either the tire is damaged and the tube blew out through the tire wall, or the tire lifted clear of the rim and the tube blew through that gap.

Moe Zhoost

It happens. Some tire/rim combos require me to inflate in steps going around the tire bead each time to ensure good seating. Odd that the shop did not fully inflate. Not a lot of extra time to do and darn good customer service.

OneIsAllYouNeed

+1

Retro Grouch 

That's one of the reasons why I stopped using co2 to re-inflate tires after I have a flat on the road. Co2 inflates so quickly that there's no opportunity to catch and correct yourself if you have inadvertently made that mistake. My hand pump allows me PLENTY of time to examine the tire beads during the inflation process.

10 Wheels

I was using a floor pump.

CO 2 is Great when you have in 80 miles in 95*F Heat,

bobwysiwyg

I carry a pump, but never look forward to having to resort to using it. I carry a CO2 inflator that permits incremental amounts of gas to be input, and then stopping to check tire pressure. I never leave home without it and 2 cartridges (threaded).

mightymax

I not too long ago had a old and repected LBS replace a spoke and true the rim. After my regular LBS guy had no clue, how to remove the freewheel, off of the Araya rim from my Concord Freedom Deluxe. I visited this 100 year old shop in the town over. The two guys in shop were great and very personable. I had the guy who the other referred to as the wheel guru repair and true. Nice job done on a slow afternoon while I waited and he charged me ten bucks. My regular guy would have charged double that! I vowed to always go to this shop for my wheel repairs, and then it came crashing down. I had to remount the tube and tire. I inspected the rim prior to this and I should have done it in the shop but I was distracted with conversation.
Anyway the Wheel Guru installed a spoke that the end was protruding an honest 1/8 inch past the slotted end of te nipple into the rim. This would have been an instant puncture flat, when the tire was inflated! I fixed the rim (dremel with grinding bit) instead of taking it back and complaining that the wheel guy set me up cause the other guy wanted to sell me a new rim for 100.00! anyway take the tire off and inspect the innards of the rim.

anyway anytime I get a flat I always inspect the inside of the rim for any sharp protruberances.

Max Bryant

canklecat

Any time I need to add a significant amount of air pressure I check the bead and tire seat all around on both sides. Learned that the hard way last year after inflating a loose fitting clincher straight to riding pressure -- BAM! inside the apartment.

I don't worry about it quite as much with tighter fitting clinchers, like the Michelins and Innovas. I need tire tools for those tires. I'll inflate to 20 psi from completely uninflated, check the bead seat. If it looks good, I'll inflate to riding pressure.

But the Specialized Hemisphere tires fit loosely. On the plus side, no tires levers needed, and they're good rolling all terrain tires that don't feel heavy. The downside, I have to inflate and check very carefully. I start with adding 20 psi from completely uninflated, then check the bead very carefully, massaging and mashing the tire against the floor or ground while rolling the wheels by hand and looking for bulges. Add another 10 psi, repeat. Keep doing that until it reaches 60 psi or so.

Broctoon

Another possibility is that the shop mechanic removed the rim strip and didn't get it back in place correctly. I've bought a few used bikes recently, and I've had at least two flats on them from spokes/nipples puncturing the inner circumference of the tubes. In each case, the rim strip turned out to be deteriorated.

Jiggle

Wow. I would be concerned that he screwed the unthreaded portion of the spoke into the nipple threads. So much for being a guru.

rumrunn6

thanks guys. the tire appears intact & a few inches of the bead popped off the rim.

when I change a tube or mount a new tire I'm very careful to fill it slowly & center & position the tube & tire evenly. my bad for rushing it

rumrunn6

finally got to this. new tube, kept the current rim strip, no problems

canklecat

Recently I put back into service the loosey-goosey fitting Specialized Hemispheres I mentioned in this thread last month. I was just curious to find the best type of tires for my 1990s era Univega mountain bike for hybridized riding -- mostly pavement, some groomed gravel/chat trails, no rough stuff.

As I remembered, the Hemispheres were smooth riding with good grip on most surfaces, more comfortable around 75-85 psi than the maximum 100 psi, but noisier than I'd remembered (a fellow cyclist in group rides noticed this as well).

But I worried every ride whether the loose fitting bead would blow off the rim at a bad time. After a week or so it was driving me nuts. I kept thinking of those blowouts last year when I thought I'd seated the bead carefully but BLAMMO! And while I got the tires seated properly this time I worried every ride for two weeks. I hate even thinking about tires while I'm riding.

I replaced 'em with new Continental Speed Rides. Great tires, much better ride experience overall, and the bead is just snug enough to be easier with plastic tire levers, but not absolutely essential for folks with gorilla mitts.

The Hemispheres aren't completely useless. They can be folded up fairly compactly, despite not being folding tires. I can loop 'em three or four times and tote one as an emergency spare. But eventually I'll tote a proper folder as a spare and retire the Hemispheres or give 'em away with a warning to the new owner.

rumrunn6

these are Michelin Pro4 Endurance folding tires max pressure 109 psi. I haven't found any web reviews stating they were prone to blowing off the rim.

the tube had an 8" tear. not sure if that helps diagnose the issue. the rim strip looked in good condition, in proper position, a fairly thick hard red material

canklecat

Yup, a long tear along the tube lengthwise is 99.99% likely to be due to the bead not being fully seated and the tube sneaked out.

Those Michelin Pro4's sound good. I'm a Michelin fan and would try 'em if I had a road bike.

Bike Gremlin

I wrote a how-to with pictures. Special attention to making sure the tyre is seated well before inflating. If not, it can explode when inflating, or seconds afterwards.

Mounting bicycle tube and tyre - Cycle Gremlin

rumrunn6

canklecat thanks fir the reassurance

Slaninar thanks for sharing that write up. great photos, did you take them? and just for the write up?

I was mounting the tire & repeating to myself all the things I've learned over the years & cautioning myself not to make common mistakes. it helps when you don't rush & take the time to massage the tire & tube into place.

when I was a kid in the '70s I used a screwdriver to pop the tire back on, at the end. I think I ruined only one tube before learning a hard lesson. I'm still tempted to use the tire levers at the end to get the tire on. but the other night I took my time getting the tire into the groove at the opposing end & massaging the tire up the sides toward the top where I was finishing & slowly rolling the remaining bead over the rim with just my hands. then exhaustively checking the tire alignment all around, pausing occasionally to inflate a few PSI, then double checking the alignment all around before the final inflation.

I was wrenching on another bike & figured well, I put this off long enough. it's been a busy fall, but I can normally change a flat roadside in 15 minutes. much nicer in the basement sitting on a stool with bright lights, my reading glasses, big pump & bike workstand.

while I can mount the rear wheel on the bikestand, I still like to finish on the ground to be sure I have it all the way in the dropouts.