presta valves

smokey

On Jun 11, 8:25*pm, "mary" <sha...@verizon.net> wrote:
> Is it just me or do tubes with presta valves have to be filled up more
> often? *It seems like once a week I have to top off the air in the tubes..
> Just wondering. Oh and before you ask, yes I make sure the valve is closed
> all of the way after filling.

The tubes themselves leak a little air. Thinner, higher pressure tubes
will be worse about this. I've tried a lot of different brands of
tubes and lately have been using the Schwalbe standard tubes. They
seem to leak less air than the others and seldom need topping up.

Smokey

Chalo

"Burr" wrote:
>
> If you are real light you can run less air but the more air the easer it
> is to turn the crakes but the more you bounce. The tour riders run
> 160-190psi.

I'd be very, very surprised if even one rider in the entire
international road racing peloton used pressure that high. Track
racers on the velodrome are known to do so, but on the road the energy
lost to slamming and vibrating the rider can far exceed any reduction
in rolling resistance achieved by using very high tire pressure. Many
Tour de France riders still use sewup tires, one of whose major
advantages is the ability to run _lower_ pressures without pinch
flatting.

Chalo

Burr

"Chalo" <chalo.colina@gmail.com> wrote in message
news:4a140380-341d-4ecb-908f-3b44299d8847@f36g2000hsa.googlegroups.com...
> "Burr" wrote:
>>
>> If you are real light you can run less air but the more air the easer
>> it
>> is to turn the crakes but the more you bounce. The tour riders run
>> 160-190psi.
>
> I'd be very, very surprised if even one rider in the entire
> international road racing peloton used pressure that high. Track
> racers on the velodrome are known to do so, but on the road the energy
> lost to slamming and vibrating the rider can far exceed any reduction
> in rolling resistance achieved by using very high tire pressure. Many
> Tour de France riders still use sewup tires, one of whose major
> advantages is the ability to run _lower_ pressures without pinch
> flatting.
>
> Chalo

I learned something. I "thought" I remembered reading about them running
very high pressure.

Burr

jobst.brandt@stanfordalumni.org

Burr who? wrote:

>>> If you are real light you can run less air but the more air the
>>> easer it is to turn the crakes but the more you bounce. The tour
>>> riders run 160-190psi.

>> I'd be very, very surprised if even one rider in the entire
>> international road racing peloton used pressure that high. Track
>> racers on the velodrome are known to do so, but on the road the
>> energy lost to slamming and vibrating the rider can far exceed any
>> reduction in rolling resistance achieved by using very high tire
>> pressure. Many Tour de France riders still use sewup tires, one of
>> whose major advantages is the ability to run _lower_ pressures
>> without pinch flatting.

Not true. The term "snake bite" pinch flat was coined over patching of
such flats in latex tube Clement tubulars. The term was important
because it was not generally known that a pinch flat causes two holes
(as pinching one's cheek with thumb and forefinger).

> I learned something. I "thought" I remembered reading about them
> running very high pressure.

Its easy to find all sorts of myth an lore about bicycle racers that
can "leap tall buildings in a single bound"

http://www.answerbag.com/q_view/110331

Men of steel whose tires are equally hard and fast. Drugs play no
role in any of that aura. Don't believe everything you hear about
bicycle racers methods and abilities.

Jobst Brandt