Arthur Ogus said:Grrr!!! It has happened again.
For some reason my floor pump doesn't like
the valve stems on my favorite tires,
Vittoria Corsa CX. About half the time,
the valve head gets pushed back into
the tube instead of entering cleanly into
the pump head. This only seems to happen
with these tires, non other. But it's more than a
nuisance, because if it happens often enough,
the tube is weakened and begins to leak.
Since these tires are sewups, it's a major headache.
The only way I have found to prevent this from happening
is to let all the air out of the tire before pumping, so that
I can support the back of the valve with my thumb. Is this
what you are supposed to do? (Of course, these valves
aren't threaded at the bottom, so one can't use a retainer
nut to hold the valve in place.)
Dear Arthur,
You can make quick and useful tools out of cheap miniature pliers with
a file,
drill press, bench grinder, and dremel tool.
Most cheap miniature plier sets include a useless pair of flat-jaw
pliers:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=4807
That kit of 5 small pliers is often on sale for $5 instead of $10. The
flat-jaw pliers are called "flat-nose" and are useless (as far as I can
tell) for anything except grabbing a very thin sheet of metal.
Grab 'em with one hand, leave the jaws slightly open, and introduce
them to a drill press, using a drill bit slightly thinner than your
smooth valve stem. The faint crack in the slightly open pliers
automatically centers the bit. Once the hole is started, squeeze the
pliers shut, and drill right through. The metal is soft enough that
this takes only a few seconds.
The jaws are more than thick enough to grab even a smooth valve stem
firmly, but thin enough that there's room for the chuck. With a hole
slightly smalIer than the valve stem (smooth or threaded), you get
4-point contact with valve stem, which is plenty. I used a handy
threaded stem of normal length for the picture, since my only smooth
valve tubes are extra-long for aero rims.
This view shows the pliers set as far as my twin-head chuck would go
onto the valve:
http://i13.tinypic.com/357gjfp.jpg
This view shows the drill bit and the hole in the pliers:
http://i13.tinypic.com/2yytqbl.jpg
With a drill press and pair of cheap pliers, it takes less time to make
the tool than to take and upload the pictures.
Cheers,
Carl Fogel