Date:    Fri, 07 Nov 1997 16:46:59 PST

Jam nuts on Presta valve stems and pumping.

1. The jam nut holds the stem when pumping so that it does not recede
   into the rim when pressing the pump head against the tire.  This is
   especially useful when the tire is flat (after installing the
   tube).  It also keeps the stem from wiggling around while pumping.
   Removing the nut should present no difficulty unless the threads
   have been damaged or the hands are cold.  The cold may present a
   problem, but then just opening the valve nut on a Presta valve
   under such conditions is difficult.

2. Breaking off stems with a frame pump comes from incorrect pumping.
   The number of new tubes with broken stems lying along the road
   proves that this occurs far too often.  To avoid breaking the stem,
   the pump head should be be held in the fist so that the pumping
   force goes from one hand into the other, not from the pump into the
   valve stem.  To practice the correct action, hold the pump head in
   one hand with the thumb over the outlet, and pump vigorously
   letting out no air.  All the force goes from one hand into the
   other.  This is essentially what should take place when inflating a
   tire.

   It does no good to "get even" with the stupid tube by discarding it
   on the road for all to see.  Most riders understand how to pump a
   tire and see this only as evidence of incompetence rather than a
   faulty tube.  Besides, this ostentatious behavior constitutes
   littering for which the the fine in California is $1000.  Bike
   shops should instruct new bike owners about the use of the frame
   pump.  Along with this there should be some tire patch hints like
   don't try to ride a freshly patched tube, carry a spare tube and
   always use the spare after patching the punctured tube.  Of course
   this is a whole subject in itself that is also treated in the FAQ.


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