An acquaintance of mine went down pretty hard about a month ago, nothing life-threatening but painful, and his bike FXD (2009, I think) had major damage. I had the chance to talk with him yesterday about the accident, and he told me that the official cause was a "catastrophic deflation of the front tire" apparently caused by the valve stem core backing out and/or blowing out (when the bike was checked over after the wreck the core was missing, so it took the blame).

Anybody here ever had a core fail? I haven't, but if that were to happen, would metal valve stem caps prevent or at least slow down that sort of failure? I'm sure the typical cheap plastic caps would just pop off immediately.

 

Never heard of that before, lve had the inner tube split quite badly around the valve stem just caused the steering to get heavy as it went down.

 

i always run metal valve caps, also replace the valve cores on each tire change

 

Just a thought maybe he over pressurised the tyre.

 

For the core to be missing, it would have had to have been unscrewing itself for a while. This is usually preceeded by the tire showing leakage! It is a good practice to replace the complete stem EVERY tire change, always check air pressure regularly and often overlooked, make sure you have a valve cap on the valve!

I have been in the automotive trade for 38 years and have never even heard of a valve core "missing", by blowing out. Glad to hear your friend is OK. The outcome could have been far worse.


BTW - over pressurizing the tire would blow the tire out WAY before a valve failure!

 

I have seen cores go out on cager tires before. Usually because they were never changed out. After the driver complaining about tire going low repeatedly I searched for a leak and that was the last place to look.
Like everyone else has said here change out the valve stems. Also, if you are messing with the valves yourself be gentle and make sure you don't cross thread them or damage them.
Hope your friend has a speedy recovery.

 

Never seen or heard of a core suddenly unscrewing itself quickly enough you would have a sudden tire delflation.

When you get home, take your core out and sit on your bike until the tire goes flat. It takes a while.

And, as others have said, it would have been leaking slowly for a time while the core worked itself loose. There should have been plenty of warning.

So the theory that the core suddnely came out at or about the time the valve cap also came off to allow it to suddenly deflate fast enough that a rider did not know it was happening and did not give him enough time to safely pull to a stop...

A stretch,,,, very thin...

 

No way it could cause a catastrophic deflation.

Even if the Schrader core blew out completely, with no warning, which is highly unlikely, the tire would still take several seconds to deflate.

Even a plastic tire stem cap would prevent that scenario from happening. I have seen plastic caps hold pressure far higher than is in a tire.

Now if he hit an object hard enough it might cause that type of failure, but there would most likely be rim and tire damage as well.

Most times the accident isn't investigated to that level unless there is a possible lawsuit involved. Accidents investigations I have seen are just damage assessments for insurance coverage. The cause isn't usually made "official" because, in the case of your buddy, he could now sue a tire manufacturer, or the last shop that worked on the tire. The insurance company won't want to defend that in a lawsuit, so the cause is usually much broader such as "rider error" or "mechanical malfunction"