No flats on double tubed wheel all summer on 60 C + pavement.

Today about 14 km into the ride, no warning whatsoever, the front wheel exploded blasting Slime all over shoes, wheels and road. The wheel was immediately on rims.

Obviously the tubes over inflated from the vapor pressure of the hot sealant and blew the tire off the rim. Hopefully the other inner tube would still hold air, even if necessary at a lower pressure. That's the whole reason for double tubing: on the go backup

Problem with that theory was the tire was still entirely on the rim. The bead was not damaged which is usually the case in over pressure bead blow outs.

Neither of the 2 tubes would hold air either. Until today a fourth tube was always taken as a spare, but, like the Titanic there was too much confidence on what multiple air filled chambers could do . . .

In town under shade dehydrated with wheel off it looked like both tubes had ripped open in the same spot almost simultaneously, one tube sliced open 10 cm and the other shredded for 15 cm.

There may be quite a few of firsts, onlys and never agains here but this is probably the first simultaneous double tube blow out to ever take place completely _inside_ the tire.

Maybe the tubes were chafing each other since the blow outs were right next to each other, about 1:30 position with valves at 12:00 and 6:00.

That theory is no good either. The rubber along the rips was still thick enough to hold air.

Any theories on what happened? No puncturing objects were found in the tire.


Bret Cahill