Descending at 50? Check your valves.

  • Home
  • Descending at 50? Check your valves.
4 replies [Last post]
Anonymous's picture

""" ... lost over an hour due to a sudden air loss on the rear tyre going down the fastest descent on the ride at 90 km/h. The bike started fishtailing at that speed but I was able to apply the brakes and get stopped in a straight line. When I came to a stop I could smell the burning rubber from the pads. I had to sit down across the street in the shade and calm down for approximately half an hour before I could repair it.""

""I told Gardner about what happened and he was familiar with this problem. He said they've had several HPVs lose their air this way in races. He says it happens over 50 mph when the valve is left open. This means one doesn't even need to have a remote valve control pressing down on the open valve to lose the air at speed, just an open valve is enough. So for bikes that go really fast down hills all the aero wheels that require valve extenders are unsafe unless it is a closeable extender like what Spinergy uses and even those are potentially unsafe as they are easy to leave open without knowing it.""

Zach Kaplan


Anonymous's picture
.arty (not verified)
thanks (nm)
Anonymous's picture
bill vojtech (not verified)

The HPVs that I've heard of with this problem used schrader valves. Presta valves SHOULD be no problem, because they get screwed closed after pumping. Or at least they're supposed to.

They solved it on the HPVs with schrader valves by installing metal valve caps with rubber seals.

Anonymous's picture
mike p (not verified)

i think they were talking about presta valves in this instance. Gardner passed away a couple years ago, so this is not a new article

Anonymous's picture
mike p (not verified)
I checked it was presta

"from zach K
""Presta in an aero wheel with valve extender and open valve."""

cycling trips