robertorolfo

(Skip to the bottom to avoid the unnecessary theatrics and get to the heart of the matter)

Scene 1:
Outside a New York apartment building, 8:45pm, July 1st, 2018

The Players:
-Me
-My GF
-My GF's Friend
-A 1986 Lotus Legend with it's original Araya SS-40 36 Spoke Super Hard Anodized wheels wearing 700 x 25c Vittoria Rubino Pro 3 tires pumped to approx 100psi (more on the pressure in a bit)

After a brief ride (.3 miles at a very leisurely pace), we find our players conversing on the sidewalk in front of the building, standing next to their bikes.
My GF: blah, blah, blah (sounds line adults talking in a Peanuts cartoon)
My GF's Friend: blah, blah, blah...

BANG!

My GF's Friend: Jesus Cr--st! What the f--k was that?
My GF: Holly sh--t that was loud!
Doorman, running out of the building: What's going on out here? Everyone Ok?
Nearby delivery guys unloading a truck: What the hell?
Me, sheepishly putting a hand up: It's OK. It's my fault.
My GF: Huh?
Me:Itwas my bike. My tire just exploded.
My GF's Friend: That was your bike? That was insanely loud. It sounded like someone fired a gun...



Scene 2:
Inside a New York apartment building, 6:05am, July 9th, 2018

The Players:
-Me
-My GF
-My GF's Dog
-A 1986 Lotus Legend with it's original Araya SS-40 36 Spoke Super Hard Anodized wheels wearing 700 x 25c Vittoria Rubino Pro 3 tires pumped to approx 85psi (more on the pressure in a bit), with a new Continental Tube

All of our players are asleep, when Me is suddenly awoken by a creaking/pinging sound similar to dragging a guitar pick slowly across a ribbed string, or similar to a slight pinging of a spoke...
BANG! (Likely startling the occupants of nearby apartments as well)
Me: I'm so sorry about that
My GF: What the... Was that your bike again? (My GF's dog has tucked his tail firmly between his legs to protect his non-existent genitalia that was so cruelly removed at a young age)
Me: Yeah, that was my tire again
My GF: Why does this keep happening?
Me: I don't know. Sorry. I feel like such a failure...


So what is going on here? First a little more background, to avoid the more obvious suggestions.

I'm a pretty decent tire and tube mounter. I haven't had many issues with pinch flats in the past. I always inspect my sidewalls and beads to make sure my tires are seated correctly before inflating to full pressure.

The first tube (a Vittoria tube) that blew out had been on the bike for at least a month, seeing near daily use as a commuter. It had been topped up multiple times during that month, always to something in the 100psi area, and there were never any issues. Prior to the most recent top-up on July 1st, just 30 minutes before the blow out, the tire was not low on pressure (it would have been 70 or 75 psi at the lowest, but probably around 85), so it seems unlikely that the pressure would have been low enough for the tube, tire or bead to have shifted or become unseated somehow.

The second tube (the Continental tube) had been on the bike for 8 days (it immediately replaced the first tube after an 8 minute tube change that was an ETERNITY to my waiting GF), and it had given me no problem. It too had never fallen to a very low pressure, and it was only topped up to 90psi on my pump gauge before blowing out while sitting still in an apartment 12 hours later. (I should probably specify that the tubes had long slits in them after the fact, and the tires were partially off the rims, indicating that the tire came off and the tube escaped prior to blowing).

More on that pump: it kinda sucks. It's a park tool "home mechanic" floor pump, and the gauge is wonky at best. When I can get it to provide a reading, it seems to fluctuate quite a bit after some actual pumping takes place. I put little faith in its accuracy, but if anything I think it is reading too high, rather than too low. This is based on the amount of tire squish (or squash) I observe at pressures at or above 100psi, which is quite a lot. But my experience with this is also limited, so...

My hypothesis: at the moment I'm thinking that these old Araya rims simply aren't a great match for these Vittoria Rubino's, and for whatever reason they aren't holding the bead securely. The tires have been on for about 6 months and several hundred miles, but maybe they have loosened up just that tiny bit as they have been broken in? It does seem like getting the bead onto the rim is easier now than when they were new.

So what do you guys think, after reading this needlessly long and dramatic wall of text? What reasons have you seen in the past for spontaneous, non-riding blowouts quite a while after the tires were filled to pressure?

Thanks in advance

DiabloScott

That'd be my hypothesis as well. Other things that will cause the explosion include:
1. Pinched tube under the bead.
2. Rip in carcass that allows tube to bubble out.
3. Damaged rim that allows the bead to lift up, or damaged/faulty bead that won't seat properly in the rim.

AnkleWork

Couldn't wade through all that, but just to respond to the headline: tires are not governed by quantum mechanics. The most likely source of the problem is user error. Just find known-good procedures to install & use tires & tubes and follow them closely.

jwh20

Actually, according to theory at least, everything including bike tires are governed by Quantum Mechanics. But the probability of observing a quantum-related effect on bike tires under the conditions we live is quite remote. Plus to see it twice in close succession is even more remote.

Any photos showing what's happening? Is it the tire or the tube? Did you check for sharp edges on your wheels? A problem with your rim tape?

AnkleWork

Tires are macro systems governed by determinism (Newtonian mechanics). Your "quite remote" probability can't even be calculated.

jwh20

I'm sure it could be calculated but I agree, the term "quite remote" is an understatement.

ksryder

I for one would like to know more about bicycle maintenance and quantum theory.

ironwood

Possibly the rim is slightly undersized, and a modern high pressure tire could blow off with high pressure. Also if the tire was left in the sun on a hot day the heat could raise the pressure enough to blow it off. Was it a tire with a folding kevalr bead?

Wheever

I would add:
Check the rim for sharp bits and integrity of the bead. The tire may be clean blowing off and letting the tube pop, or a sharp bit is randomly slicing the tube.
Check rim tape for wear
Check tire for thin or small protruding foreign objects (Riding in NYC is what got me to switch to tubeless. too many thin wires piercing the tubes,)

Now, none of the above scenarios usually result in a BANG, but what would would be a flaw or weak spot in the tire bead itself. Inspect the tires carefully.

leob1

Check that the tire bead and the rim bead are compatible. If the tire is designed for a hook bead, it will not work well with a non-hook bead rim, like the ones on you 1986 Lotus.
They stretched after being mounted for a while, and now the tire isn't seating well on the rim, letting the tube slip under the bead and KABLAM!

Iride01 

I have no idea how or why, but my expectation is that the tire and rim aren't a great match and that the tire blew off the rim first which is why the sound of the explosion was loud. If the tire started coming apart first, I'd expect it to be a quieter sounding explosion.

Might be entirely the opposite, but that's what I imagine as when I blew my tires off the rims a few times, it was loud.

Of course gauge error causing them to be way over pressure might be a factor too. Was the tire damaged as a result?

zacster

The OP did say that the pump was wonky. So if he overinflated the tire and the tire/rim combo is a little loose, it could potentially blow off. Add to that that on July 1st the temps were like 100F here in NYC. The second blow out was probably caused by the first. I just had another thought on re-reading this. Did you damage the rim in any way recently? Any minor spills that you didn't give any thought to?

I blew out a tire on Saturday, July 7, but on inspection I found a small tear and it was a tire that needed replacing. I also recall having a small problem when pumping and maybe I overinflated it. It wasn't a pop but a pfft pfft pfft, and it was only 2 miles into what was to be a 100 mile ride. My wife picked me up and drove me to the LBS when it opened and I put a new tire on and did 75 of those hundred. I ran out of time, good roads and patience to finish the 100 but it was still a good ride.

AnkleWork

There is no theory to suggest that quantum fluctuation can occur in unison in a macro system, thus no basis for any calculation. In fact, quantum theory prohibits macro systems from quantum behavior. However, if you'd like to put forth a new theory I'd love to read it.

robertorolfo

Lot's of good feedback here, and I'm really thinking this might be the case. I'd say I generally run at fairly low pressures (the 75-85 range), so that's probably why it hasn't happened more often, or since.

Good memory! July 1st was indeed very hot, and I thought that was part of the issue, but the second time was after the bike had been inside my GF's air-conditioned apartment for over 10 hours, after being inflated in my own, non-airconditioned apartment. So I don't think it was temperature related.

And I don't think it was drastically over-inflated. My pump gauge is unreliable, but I've never gone above 115 psi with it, and that night I didn't go above 105, while the tires are rated on the sidewall for 130.

And the tire itself seems to be in good condition, although I did notice that along the bead in some places the rubber has worn through to expose some threading (I think it's threading) underneath. And for the person that asked, yes, they are folding bead tires.

Rims and rim-tape also looked good, but every day brings a chance for some damage here in the big city, so nothing is 100% certain. I've been riding on a replacement tube since Monday, though, at around 75psi, and I haven't had an issue.

Also, just to mention again, both blown out tubes had long slits in them (around 8 inches long), so I'm pretty sure the tire was coming off the rim and letting the tube escape to blow itself up.


Forgive me for sounding noobish, but do they make folding bead tires designed for a non-hook bead rim? Am I asking too much of my vintage equipment?

Again, pardon my unenlightened question, but I thought the whole point of Quantum theory was to fill in those blanks where Newtonian mechanics come up short. Of course it isn't going to explain what is going on with my tire, but isn't it involved in everything on some level? I mean, my conclusion from my forays into this topic has always been that we really don't understand exactly what is going on in our universe, so...

Trakhak

Folding tires work only on hook bead rims. That bike should have enough clearance to take 32-mm-wide (nonfolding) tires, which would work well for the maximum of 75 psi that you could safely get away with using those rims.

Colnago Mixte

OP, have you recently switched to wider tires? I have some 28 mm GP 4000 tires that have been blowing out tubes left and right, on different sets of rims, generally at night when I'm not even on the bike. Usually, the hole develops on the inside of the tube next to the rim strip. At first I assumed it was a bad rim strip, but I've ruled that out.

The last hole was actually a split in the inner tube's inside seam. I suck my finger in it, and the tube easily tore open a 4 inch long gash along the seam. An inner tube should not tear so easily, IMO.

For myself, I see two possibilities, either the bulk Chinese inner tubes I bought are defective, or, a a GP 4000 tire is just too wide for the 23-25 mm tubes I have been using, and is stretching them out and causing them to burst. Ordered some wider tubes last night, hopefully this helps.

zacster

My point on the second blow out is that once the first happened, the second was going to happen too if you didn't fix the problem, especially if the tire was damaged on the first. And don't discount the damaged rim theory, it doesn't take much. Also I didn't originally see that this isn't a modern rim, if this rim is over 30 years old none of what just happened would surprise me. Accumulated damage from 30 years could easily have caused this.

ironwood

There has been a lot of discussion about tire width and pressure on a number of different forums. Twenty years ago I upped the pressure in narrow tires and they blew off just like the OP's did. Since that time I've been riding wider tires at lower pressures. Now my favorite tires are 650B x42mm Compass tires at between 40 and 45 psi. Eventually we find what works best for us.

Kovkov

I would proceed with substitution principle:

1. We can take Your GF's friend and Your GF's dog out of the equation.
2. Try another tube brand/type
3. Try another tire brand/type
4. Try another rim brand/type
5. Try another GF

ramzilla

This is exactly why I started using wire bead tires & thorn proof tubes on my older rims.

robertorolfo

Wow, somehow I have never heard that bit of info before. Thanks!

Not sure if I could fit 32mm tires though. There is plenty of clearance width wise, but I assume there would be a slight increase in height, and I only have a few MM of clearance underneath the rear brake caliper pivot.

It's certainly old, but I'm not sure how much use it has seen. I get the impression that, like many bikes, it was ridden a little bit at the start of its life and then spent 25+ years sitting stationary somewhere (unfortunately, in my bike's case, that somewhere was outdoors for a while, because the paint is pretty badly faded).

Seems like I might have to go in this direction, but it would be a shame to burden this bike. The frame is pretty light for steel (Tange 1), and the bike is lovely to ride. This past week at 75psi has been totally fine, and I think I could live with that if it doesn't present any issues.

Which Lotus model do you have, BTW?

I do have a newer pair of Mavic wheels going unused at the moment, but I'd have to swap hubs to keep my current groupset (Shimano 600 SIS), which is working quite well despite all those years of neglect.

As for the GF, if only they were like bikes: you can have more than one at a time, and just pick which one you want to ride on a particular day...

SkyDog75

According to this old Araya catalog shot I found, it looks like SS-40 rims had a hooked bead. If so, we should be able to rule out hook-beaded tires on straight-sided rims as the source of the problem. (It would be pretty easy for robertorolfo to confirm whether or not the rims have a hooked bead in person.)

BTW: If we were dealing with straight-sided rims, I'm not sure that it makes any difference whether a tire has a folding bead or not. It obviously makes a difference whether the tire has a straight-sided or hooked bead, and hooked tires may need to be run at low-to-moderate pressure so they don't blow off the rim. But all other things being equal in regard to tire construction, an aramid fiber (e.g. Kevlar) filament inside a folding tire's bead should perform pretty much the same as a steel wire in a non-folding tire. Both materials are capable of withstanding the tire's pressure and will thus hold a tire's circular shape when inflated. And it might seem counter-intuitive since Kevlar is quite flexible, but it's actually much more resistant to stretching than steel.

Getting back to the actual problem... Between the slit in the tube, the 'bang', and the tire being off the rim, it does sound like the tire's bead is somehow becoming unseated. It could just be a poorly matching tire/rim combo. It could be that you got the tube pinched under the tire's bead when mounting/inflating. It wouldn't explain the tire being off the rim, but a problem with rim strips or tape can cause blowouts on a double-sided rim, as the tube can expand into spoke holes and stretch 'til it ruptures. (What kind of rim tape or strips are you using?)

bicyclridr4life

I had the same problem, with BOTH front and rear on a brand new 2004 Giant Cypress DX. One or both tires would blow after only 15 minutes or so, ridden or not.
Rim tape was replaced a couple times, tubes replaced several times.
I finally found the problem in 2011, after managing to put 150 miles on the bike.

Both tires (Kenda) had a small defect in the sidewall, that allowed the tube to bubble out.

A new used set of tires fixed the problem.

Try changing your tires.

Unapomer

What Trakhak said. Been there, done that and I have seen it many times

Kontact 

You can tell immediately after a blowout if the bead crept or the sidewall blew out. You just have to look.

My money is on the tire being mounted incorrectly. It was either too deep in the rim in some spots creating slack in other spots, or the tube was partially under the bead. Assemble your tires with the tube partially inflated so it can't pinch under the bead, and pay attention to how concentric the tire is to the rim as you inflate it. Some tires will do this if the pressure falls too low in storage - you pump them back up, but they've shifted and blow out.