"Elisa Francesca Roselli" <[email hidden]> wrote in message
news:[email hidden]...
Quoted message said:I keep the tyres on my large wheeled bikes pumped to about 4 bar.
Is
Quoted message said:this too much for smaller wheels?
That's probably about right, but as everyone else has pointed out, it
will tell you on the side of the tyre. With all those Americans
ready to sue for any excuse, there will be a generous margin beyond
the official number.
Wheels do wear out, eventually, as brakes rub on the side and wear
the rim away. Start checking at about 15-20 000 km. If the rim has
worn thin, a highly pressurised tyre can bow the rim outwards, which
you will be able to see. Lightweight racing wheels will wear out
sooner than utility wheels, although the rims on a smaller wheel pass
the brake blocks more often. Therefore, I suppose, other things
being equal, a small wheel should wear out more quickly. Other
things never are equal, though. Utility bikes are usually built for
strength, even at the cost of extra weight, but with a racing bike,
so long as the bike falls to pieces 10 metres after the finish line,
and not 10 metres before, nobody cares. Anyway, if you are female,
you are probably on the lighter side of average weights, and so will
not be braking as hard, and wearing rims as hard, as most other
people
The use is mainly road, but with
Quoted message said:occasional frequentation of a very nasty off-road path with lots of
mud
Quoted message said:and pointy stones. I'm paranoid about the puncture fairy because I
have
Quoted message said:no local backup or support on this bike.
Also, it has Schrader valves. I notice that even when I pump it to
4
Quoted message said:bar, it takes so long to unscrew the valve that the air-loss brings
it
Quoted message said:back down to about 2 bar. The effect is more dramatic on the
smaller
Quoted message said:wheels since proportionally more air is lost when unscrewing the
valve.
Yes, again see everybody else's comments. The pumps which screw on
are ***MUCH*** worse in every way than a good modern pump. If it's a
pump with a rubber hose, replace the pump as soon as possible.
Schraeder valves always tend to be more difficult to pump up than
presta valves, because there is a spring in the valve, and you have
to pump against some of the force of the spring, not just against the
pressure of the air in the tyre.
In theory there's a pin in the pump to hold the spring down, but it
never seems to completely work. With some schreader valves you can
take the valve out of the tyre, and then chop the valve in half with
a pair of wire cutters, thus destroying the spring, and making the
tyre much easier to pump. However, I'm not sure that you can do
that with modern valves (I use presta valves, so I'm not really up to
date on schraeders)
Jeremy Parker
