Old 07-11-18, 11:39 AM
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robertorolfo
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Bing Bang Theories? (Or Why My Tires are Randomly Exploding?)

(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

Last edited by robertorolfo; 07-11-18 at 11:47 AM.
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