GSmith

So, I ordered a new set of tires for my CAAD 9. One of them came today, the other's back ordered. So, I installed the new one today on my rear wheel. The tire is a Schwalbe Durano S. I inflated the tire after installation to 140PSI - this was probably a dumb move, the tire was rated to 145 but either the inner tube somehow was not rated that high (though I don't think tubes have PSI ratings..?) or I installed incorrectly. Anyways, I hung the bike up and 15 minutes later it burst (helluva sound). The bead blew right off the rim - tire totally fine on visual inspection, inner tube had a massive tear in it. So, if it wasn't an issue of too high a PSI, I pinched the tube in the bead.. it was a more difficult installation than ones I've done in the past, so it's totally possible.

If that was that, I wouldn't have any questions, but then after installing a new tube and inflating to 120, and then topping up my front tire from around 90 to 120 (what I've been inflating to for two years on the same tube), the FRONT tire popped a couple hours later. This is BIZARRE, the only thing I did to the front tire was top it up absolutely as usual. In fact, I have NEVER removed the front tire (amazingly, not a single flat in over 3000km in 2 years).

So, I'm baffled. I would totally understand installation error causing the rear tube malfunction, but the front too? As far as I know explosive deflations like that are rare outside of cases of improper installations, and like I said, I've done over 3000k on that tire without ever un- or re-installing it.

Have at it guys, I'm at a loss! Cheers for any input!

10 Wheels

I blame it on your signature......

Put in new tubes and try again.

How large was the tear in the front tube?

jchabalk 

yikes, sounds like it's time for an exorcism! i don't even know what to say about it, probably just a coincidence.

I assume that you're using the same pump that you've used for years too right? it might be worth just making sure that the gauge didn't fail and is actually reading lower than actual? that's the only thing i can think of other than just re-tubing both wheels.

jchabalk 

hah, that's exactly it, i didn't notice the sig.

10 Wheels

I had this blow out at 17 mph on the front wheel.
It had been in the tire for 400 miles.



Cause Unknown**********?

GSmith

Haha, fair point, well played. The front tube's tear wasn't much of a tear, more of a small puncture kind of hole with small tears in 4-5 directions from it - in total the hole was no more than a quarter centimeter though, and that's a bit generous. I have a new tube in the rear again, no explosions yet but I'm half on edge waiting for it now.

I just cannot explain what provoked the front tube damage. The rear incident I can live with.

fishymamba

My friend's really old C.Itoh bike ate 4 of my tubes in the same way. It turned out that the tubes we were using were not the correct size for the tire. My tubes were for 700x18 to 700x23 and his tires were 700x28.

cudak888 

First, I wouldn't begin comparing this to an older bike with straight-side or bulged bead rims. Different animal all together.

Examine your rim's hooked beads to make sure and your rim liners aren't interfering with the hook. Also examine the bead on your tires; could be that the new one is defective, and the front that you replaced might have had some damage. Note the location the tube split, find the center of the tear, and then examine that portion of the rim, for that's where the tire worked itself off the bead.

-Kurt

GSmith

@jchabalk Same pump, a fairly high end Lezyne. I don't think there's anything wrong with the gauge, I use it for my commuter as well and the pressures always seem right (value vs. feel), I'm careful about it because it's hard to get in that small comfort/safety/speed zone on Toronto's icy/slushy roads right now.

@10Wheels Impressive, I've never heard of that happening.. an explosive blow-out under normal circumstances, that is. Mind you, I haven't been in road cycling for too long.

@fishymamba I could see that being an issue, haha - mine are definitely correct, 700x23 on both of my bikes so my purchases are always exactly that. Also, as I explained with the front tire, 3000+km and 2 years, no way that was it (also, correct on inspection afterwards).

GSmith

Thanks for the tips, I took a quick look around the front rim in between the explosion and replacement, and again just now (have to pick up another tube and some spares tomorrow), but couldn't see any abnormalities - it's true as can be. The rim liners are very solid on these wheels - Shimano WH-RS10's (stock), very well formed to the deepest point of the rim. No abnormalities that I can see. If there's any specific way to feel out problems, let me know, this is all basically running my fingers around the rim/liner.

cudak888 

Hmm. I must echo the other fellows then - what were the tubes marked as? Could have been 28C+ in an 18C+ box.

Try a different manufacturer (not brand, manufacturer - examine what's in the box before buying) of tubes, just for the heck of it. Can't hurt.

-Kurt

Burton

On the bright side - at least it happenned at home!

Can`t say I can do anything but speculate - so a few questions: Were those Were those Schwalbe tubes as well as Schwalbe tires? Never had any issues with defective tubes from Schwalbe myself but did have 4 from Kenda last year. The firt two were actually on new bikes and blew after the bikes were assembled and hung up - but not right away. The first one went off at 2AM and set off the alarm. Course we didn`t realize what had set off the alarm until the 2nd one went off the next day. Those were only inflated to 65 lbs. The other 2 blew on their own while being inflated after installation to repail flats. A long split is indicative of tube failure rather than a puncture.

Your front sounds like a coincidence. Sounds like a pressure point failure, but its likely that after 2 years at 140 lbs the tube was just tired.

My only other question is- did you half inflate the tube before installing the tire? If yes why do you feel you might have pinched the tube? Should be impossible. If no- then it is possible that the tube was twisted and inflating it to 140 lbs could straighten it and in doing so, literally lift one side of the tire out of the bead, giving the tube a chance to expand through the gap and explode sidewise.

Of course that`s just speculation. But I`ll bet you`ll be looking over your shoulder for at least a couple days!

xyzzy834

I've had this happen twice before I realized what was happening. Same scenario. New tube installed. Proper inflation. Five to 15 minutes later... BAM! Tire blown halfway off the rim. Tube split wide open for 10" or so.

In my case, I was careful to get the tube centered and untwisted in the tire before inflating. However, upon initial inflation the tube expanded and forced a bit of itself around the tire and between the tire and the rim near the valve stem. The tubes are a little thicker there to support the valve stem. I'm pretty sure it wasn't sticking out of the rim, but a piece of the tube was caught between the rim and the tire. After a few minutes, the whole thing gives way with a huge bang.

Now I inflate my tires in two steps after replacing a tube. In step one, I pump only a small amount of air in to the tube. Just enough to give it a true tubular shape. Then I carefully work my fingers around both sides of the rim to make sure nothing is caught, especially near the valve stem. Then inflate fully.

I've been doing it that way for several years now with no exploded tubes.

skilsaw

+1

I'v had a tube blow when inflating it the first time and have assumed it was twisted inside the tire, or pinched by the rim.

Your front tube is a total mystery to me.

Al1943

With high pressure road tires if any part of the tube is caught between the any part of tire bead and the rim the tube will sooner or later find its way out and explode.
Be sure to check between the edge of the bead and the bottom of the rim, it's easy to overlook this possibility.
It really helps to put a small amount of air in the tube before mounting. Using your mouth to blow into the tube will result in about the right amount of pressure.
Pushing the valve stem into the tire will help eliminate a pinch at the base of the valve stem.

GSmith

Seems me conclusion matches the general consensus - complete fluke. I do indeed inflate the tube in two stages, so Burton, you're probably right there in part that that would make it much harder - but this was my first time reinstalling a tube on these wheels, and to be honest it was a bit more difficult than the wheels I've done it on before, all older or cheaper and for whatever reason much more forgiving of forcing the tube in whatever which way. I'm pretty careful about getting any twists out. and about how deeply I insert the levers so as not to mess with the tube inside so much.

Anyways.. brant new Bontrager tubes in of the perfect fit, I'll definitely be posting back if another explodes.

DannoXYZ 

Here's a step I find cures the unexpected blowouts for good:

1. after mounting the tyre, let out all the air
2. pull the tyre sideways and inspect the gap between the rim-edge and tyre, no tube should be visible!
3. let go and move down the tyre 20cm and pull tyre sideways again., no tube should be visible!
4. work your way all around the tyre on one side, then repeat for the other side.
5. the tube at the valve-stem is very prone to being pinched, so push up on the valve-stem back into the tyre to seat it fully inside
6. only and only when you have inspected the tyre all the way around on both sides, then you can pump it up.

conspiratemus1

I hope you insert levers only to remove the tire, not to remount it. Granted the damage to the tube from levering a tire onto the rim usually causes the tube to leak immediately on first inflation, not a blow-out, but it's still poor practice.